Visitors : 90027
International Rubber Conference 2007
17/12/2007
12-13 November 2007, Siem Reap, Cambodia

·         19 countries: Cambodia, China, Columbia, Ethiopia, France, Guatemala, India, Indonesia, Ivory Coast, Japan, Lao, Malaysia, Myanmar, Nigeria, Philippines, Sri Lanka, Thailand, United Kingdom, Vietnam.

·         300 participants.

·         80 research papers.

 

1

Growth and Early Yield of RRIM 2000 Series Clones in Trial and

Commercial Plantings

Chan Weng Hoong

Advanced Agriecological Research Sdn Bhd

Locked Bag 212, Sungei Buloh Post Office, 47000 Sungei Buloh, Selangor, Malaysia

Abstract

The RRIM 2000 series clones planted in a large plantation group had already beenreported by Chan et al., (2003) and Chan, (2004).

Twelve of the RRIM 2000 series clones bred by the Malaysian Rubber Board (MRB) and initially reported in 1995 by Ramli et al., (1995) were planted in the plantation group. These comprised the First and Second Selections, parentage of which is either ‘Local x Local` or ‘Local x Brazilian`. Among the First Selection clones, RRIM 2002,RRIM 2015, RRIM 2016 and RRIM 2020 have ‘Local x Brazilian`parentage while RRIM 2023, RRIM 2024 and RRIM 2025 of the Second Selection also belong to this category. The ‘Local x Local` clones comprise RRIM 2001, RRIM 2008, RRIM 2009, RRIM 2014 and RRIM 2026.

As of 2005, the hectarage of the RRIM 2000 series planted in the Group occupied 3513 ha (Table 1). No RRIM 2000 series were planted after 2005.

The earliest plantings of the RRIM 2000 series clones in the Group were carried out in 1998. The 1998 to 2000 plantings have already been opened for tapping from 2004 to 2006.

This paper provides an update of the RRIM 2000 series clones in respect of growth during the immature phase and early yields in the trial reported earlier (Chan, 2004) and also early yields in commercial plantings.

2

Non-Structural Carbohydrate Variability in Hevea Clones

Pisamai Chantuma 1, Philippe Thaler 2, Andre Clemendement 3,

Eric Gohet 3, Arak Chantuma 1, Teerachart Vichichonchai 1

1. Chachoengsao Rubber Research Center of Thailand, Sanamchaikhet, Chachoengsao24160,

Thailand. (Corresponding author, e-mail: pischantuma@yahoo.com)

2/ Cirad, Départment PERSYST, Kasetsart University, Bangkok 10900, Thailand.

3/ Cirad, Department PERSYST, Avenue Agropolis, 34398 Montpellier Cedex 5, France.

Abstract

The aim of study was assessed clonal variability of starch and sugar soluble (SS) in trunk of rubber tree. The two experiments were set up, the first field compared 25 clones tested in an international clone exchange program which is now 30 years old. A second field clone trial was used for 15 years trees, with 18 clones. The results showed that an average starch in wood 71 mgGLU/gSDM and SS wood 21 mgGLU/gSDM recorded 25 clones exchange trial at 30 years were similar to the average obtained the same season in the previous study on standard clone RRIM600 age 11 years, starch 76 mgGLU/gSDM and SS 16 mgGLU/gSDM. However, mean contents SS bark 37 mgGLU/gSDM, and particularly starch in bark 25 mgGLU/gSDM were higher in the 30 years tree than the previous study SS 22 mgGLU/gSDM and starch 11 mgGLU/gSDM. The 15 years trial with 18 clones, mean content in wood were a bit higher for both starch 94 mgGLU/gSDM and SS 28 mgGLU/gSDM than the previous study. The bark SS 22 mgGLU/gSDM was similar as above but starch 41 mgGLU/gSDM was much higher than RRIM 600 age 11 years. Starch and SS in wood seems not much variable with age, However, carbohydrate contents in bark varied widely. The main source of variation may be the status of the bark. Nevertheless, there was a negative correlation between cumulative yield and starch content in the bark. Carbohydrate contents in clones had a high variability and heritability. Some interesting trends linking contents in the different forms of carbohydrate to clonal origin or to a well known metabolic characteristic were also detected.

Keywords: Hevea brasiliensis, rubber clones, latex, girth, total non-structural, carbohydrate (TNC), starch, soluble sugar (SS)

3

Cloning and Characterization of Specific Molecular Markers of

Rubber Tree Trunk Phloem Necrosis

C. Charoenwut1, P. Kongsawadworakul2, J.P. Pichaut2,3, D. Nandris3, U. Sookmark2,

J. Narangajavana1 and H. Chrestin2,3

1. Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok,Thailand

2. Department of Plant Science, Faculty of Science, Mahidol University, Bangkok, Thailand

3. Institut de Recherche pour le Développement (IRD), Montpellier, France

Abstract

Trunk Phloem Necrosis (TPN) is a complex physiological syndrome widely found inrubber tree (Hevea brasiliensis) plantation. TPN is favored by accumulation of various stresses, leading to a rather abrupt, total and often irreversible cessation of latex flow. However, the very first initial molecular and cellular events leading to TPN remain unclear. To investigate the molecular mechanism of TPN outbreak, and look for specific molecular markers of this disease, the analysis of differentially expressed genes in TPN and healthy trees using a PCR-based suppression subtractive hybridization (SSH) technique had previously been performed. The mRNA isolated from TPN-affected trees, at the early stage of the isease, was used as “tester” and the mRNA isolated from healthy trees was used as “driver” and vice versa. After EST sequencing of our phloem SSH libraries, the differentially enriched cDNA fragments had been analyzed and identified using the EST-Data Base (ESTDB) software pipeline (Genetrop/IRD), including the NCBI blast program, and classified according to their functions (Kongsawadworakul et al., 2005).

In this communication we report that macroarray analysis was performed to confirm the differential expression of those genes. From the macroarray data, some genes were confirmed to be highly up-regulated in the phloem of trees undergoing the TPN disease. Among them three unknown-function genes, showing the highest expression level in TPN trees, were selected as the best candidate genes : two “No hit” (unknw1 and unknw2) and one Stress and Disease Related Protein (Sdrp). Northern blot analysis confirmed high expression level of the unknw1 genes in the phloem at the bottom part of the trunk of necrotic (early stage of the disease) trees only, compared to healthy trees, in both the PB260 and GT1 rubber clones. These results were confirmed for all the 3 genes on more trees by semi-quantitative RT-PCR. We checked the expression pattern of these genes along the bottom part of the trunk of trees (PB260 and GT1 clones) developing early step of the disease (expansion of the inner phloem necrosis from the rootstock-scion junction towards the tapping cut). Semi-quantitative RT-PCR

showed the highest expression of these 3 genes nearby the tapping cut, i.e. at the front of the extending disease, compared to the underneath areas already exhibiting severe necrotic symptoms. The tapped and untapped healthy trees did not significantly express these genes whatever the sampling area. High over expression of these genes was confirmed by qRT-PCR. The full-length cDNA clones of these unknown-function TPN molecular markers are presently under cloning, for further characterization.

Keywords : bark necrosis, gene expression, Hevea brasiliensis, SSH library, TPN, TPD

4

Genetic Diversity of Hevea IRRDB'81 Collection
Assessed by RAPD Markers

Lai Van Lam, Tran Thanh, Vu Thi Quynh Chi and Le Mau Tuy

Rubber Research Institute of Vietnam

177 Hai Ba Trung Street, District 3, Ho Chi Minh City, Vietnam

Abstract

The majority of Hevea (Hevea brasiliensis Muell. Arg.) genetic resource in Vietnam derived from the IRRDB'81 germplasm collected in the Amazonian habitats of the genus. Random amplified polymorphic DNA (RAPD) analysis was used to examine the genetic diversity and structure of the IRRDB'81 germplasm. A total of 59 accessions from 13 different districts of the Brazilian states namely Acre, Rondonia and Mato Grosso were brought into the study using six arbitrarily preselected primers. Sixty-five RAPD band patterns ranging in sizes from 0.2 to 3.0 Kbp were scored for analysis. Differences in the level of DNA polymorphism among the districts and states were revealed. The percentage of the polymorphic DNA fragments calculated for 13 individual districts varied from 15.38% to 70.77%. The mean values of heterozygosity within the district varied from 0.064 to 0.264. Pairwise district Nei’s genetic distance values ranged from 0.046 for Catriquacu and Itanba of Mato Grosso to 0.304 for Tarauaca of Acre and Aracatuba of Mato Grosso. The estimated values of Shannon’s diversity index ranged from 0.093 for the Assis-Brasil district of Acre to 0.389 for the Jiparana district of Rondonia. The analysis of molecular variance (AMOVA) indicated that most of the genetic variations were found among accessions within the districts, while inter-district variance component accounted for 14.0% only. The low inter-district differentiation probably implied an extensive gene flow among them. Both the principal coordinate analysis and UPGMA cluster analysis (of) based on genetic distance values revealed a varying degree of separation among the districts and that conformed to geographical origins of Hevea IRRDB'81 collection.

Keywords: genetic distance, genetic diversity, Hevea brasiliensis, IRRDB'81 collection, RAPD markers.

5

Differentiating Corynespora Cassiicola Isolated From Hevea Plantations in Malaysia Using Inter Simple Sequence Repeat (ISSR) Markers

Nguyen Anh Nghia(1,2), Jugah Kadir(2), Adam Malik(3), Mohd. Puad Abdullah(2),

E. Sunderasan (3), Suhaimi Napis(2)*

1. Rubber Research Institute of Vietnam, 177 Hai Ba Trung St., District 3, Ho Chi Minh City,

Vietnam

2. Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia

3. RRIM, Malaysian Rubber Board, 47000 Sungai Buloh, Selangor, Malaysia

*Corresponding author

Abstract

Inter simple sequence repeat (ISSR) markers technique was employed to differentiate 21 Corynespora cassiicola isolates obtained from a number of clones (series PB, RRIM and BA) grown in rubber plantations in Malaysia. The isolates used in this study were accumulated from 1998 to 2005, mainly from the states of Johor, Selangor, Perak, Pahang, Kedah Terengganu and Sarawak A total of 45 consistently amplified DNA bands were generated from 5 ISSR primers (UBC ISSR primers 826, 828, 835, 840 and 850), in which 98% were polymorphic. A dendrogram produced from UPGMA analysis based on Nei and Li’s coefficient divided the 21 isolates into 2 main clusters. Cluster 1 encompasses 12 isolates from Johor and Selangor. This cluster is split into 2 subclusters (1A, 1B). Subcluster 1B consists of a unique isolate, CKT05D. Cluster 2 comprises 9 isolates that were obtained from the other states. The results of detached leaf assay performed on the rubber clones RRIM 600, RRIM 2020, PB 260, RRIM 928, RRIM 2014, and KT 39/35, inoculated with the representative isolates (CKT05A, CKT05D and CLN 16) indicated that the isolates in cluster 1, with the exception of CKT05D, resembled that of race 1 and the isolates in cluster 2 showed similarity to race 2. While the two races were previously identified in Malaysia, CKT05D although grouped in cluster 1, its infectivity was dissimilar.

Keywords: Corynespora cassiicola, Hevea brasiliensis, Inter Simple Sequence Repeat (ISSR), single spore isolation, detached leaf assay.

6

Preliminary Result on the Potential of Ozonation

in the Treatment of Rubber Processing Wastewater

Nguyen Ngoc Bich1, Nguyen Thanh Binh1

1Rubber Research Institute of Vietnam

177, Hai Ba Trung, District 3, Ho Chi Minh City, Vietnam

Abstract

An investigation into the application of ozone treatment onto rubber processing wastewater revealed some feasibility. Experimental runs were conducted with diluted latex concentrate processing wastewater in 50-litre reactors. Ozonation was carried out at the first and the final stages of the biological treatment. The application dosage was about 263 mg O3/L. With the raw wastewater, ozonation could remove about 10% of the organic pollutants, but the suspended solids removal was insignificant. Ozone showed little effect on the efficiency of the subsequent aerobic treatment. Ozonation demonstrated remarkable capability in the removal of ammonia in the biologically treated wastewater, with or without hydrogen peroxide as catalyst. The final ammonia concentration was recorded as lower than 1 mg/L.

Keywords: Ozonation, ammonia, rubber processing wastewater

7

Recent Status of Rubberwood Utilization in Cambodia

Akira SHIGEMATSU1, Kumiko IDE2, Kakada KHUN3, Muthavy PHENG3, Nobuya

MIZOUE1, Top Neth4, Shigejiro YOSHIDA1, Katsuhisa KOROKI2, Noriko SATO2

1. Forest Management Laboratory, Kyushu University. 5-6-1 Hakozaki, Fukuoka Japan.

2. Forest Policy Laboratory, Kyushu University. 5-6-1 Hakozaki, Fukuoka Japan.

3. Rubber Development Department, General Directorate of Rubber Plantations. No. 48,

Vithei Neary Khlahan St. Sras Chak Quarter, Khan Daun Penh, Phnom Penh, Cambodia.

4. Natural Resources and the Environmental Unit, Cambodia Development Resource Institute

(CDRI). No. 56, St. 315, Tuol Kork, Phnom Penh, Cambodia.

Abstract

The purpose of this presentation is to show the recent state of rubberwood utilization in Cambodia. In 1996, the Ministry of Agriculture, Forestry and Fisheries (MAFF) set up the Cutting Old Rubber Program (CORP), which is to cut down old rubber trees exceeding 33-year old in 7 state-owned rubber plantations. As rubber industry had been suspended during the civil dispute, a number of old rubber trees were still remained in 1996. Under this CORP, approximately 32,000 ha will be cut down by the year of 2011. In order to clarify how old rubber trees are utilized, we interviewed 4 firms out of 8 in

total, which are still processing rubberwood under this program. The topics asked in this survey are: a) Profits generated through the supply chain of rubberwood, which is the flow from collection of raw material to distribution of products, b) Costs required for the supply-chain of it and c) Changes in the Business Environment and future perspectives for the supply of rubberwood. As a result, following three points were revealed: 1) High Efficiency and Impact of CORP: periods as well as amounts of utilization were carried out as they were planned, and more than 3500 factory workers were employed with the emergence of this CORP. 2) Three kinds of Supply-Chain; sawntimber export utilizing stems, fuelwood production utilizing residuals, and plywood production utilizing trunks. 3) Rubberwood supply was at its best in 2004 and it would be gradually declining after that. It was also found that rubberwood will be in short supply after this CORP, since rubber planting was almost terminated in 1970’s.

Keyword: Rubberwood, Cutting Old Rubber Program (CORP), Supply-Chain.

8

Below- and Above- Ground Biomass of Heveaculture in Cambodia

Kakada Khun 1, Nobuya Mizoue 2, Koichiro Gyokusen 2, Shinya Koga2,
Muthavy Pheng 1, Chan Chhek 3, Shigejiro Yoshida 2

1- General Directorate of Rubber Plantations (GDRP) , Department of Rubber Development, # 48, Vithei Neary Klahan, Sangkat Sras Chok, Khan Daun Penh, Phnom Penh, Cambodia

2 - Department of Forest and Forest Products Sciences, Faculty of Agriculture, Kyushu University, Fukuoka, Japan

3 - Cambodian Rubber Research Institute (CRRI) , # 09, St 289, Boeung Kak I, Toul Kork, Penh, Phnom Penh, Cambodia

Abstract

Tree biomass plays a key role in sustainable management and in estimating forest carbon stocks. However, there have been very few studies on biomass of Heveaculture. The objective of this study is to develop equations of below - and above - ground biomass for three common rubber clones, GT1, PR107 and PB235 planted in Cambodia.

We cut down 56 trees for the three clones and measured the oven dried weight for each part of leaves, branch, stem and root. We used the most common mathematic model in biomass studies; the forms of the power function of M = aDbHc where a, b and c are the allometric coefficients to be determined by empirical data, and M is the total below- and above- ground biomass for a specific diameter at breast height, D and total height, H. Finally, the total below - and above - ground biomass of the above three clones at the common rotation age of 25 years were estimated about 22.92 t.ha-1, 126.64 t.ha-1 ; 15.48 t.ha-1, 110.44 t.ha-1 and 21.74 t.ha-1, 171.61 t.ha-1 respectively.

Keywords: Below - and above - ground biomass; Allometric biomass equations; Diameter at breast height; Total height.

9

Rubber Particles Proteins and Sensitivity to the Tapping Panel Dryness at Hevea brasiliensis

K. Dian 1, K.M. Okoma 2, A. Sangare 3, and S. Ake 2

1. Société Hévéicole du Go (hevego), 01 BP 7572 Abidjan 01 Côte d’Ivoire (Ivory Coast) Tel.: (225) 22 400 900 / (225) 34 730 102; Fax: (225) 22 400 908 / (225) 34 730 099; Office E-mail: hevegosa@aviso.ci; Personal E-mail: diankouadio@yahoo.fr

2. Université de Cocody-Abidjan, UFR de Biosciences, Laboratoire de génétique. 22 BP 582 Abidjan 22, Côte d’Ivoire, Tel : (225) 22-44-40-19, Fax : (225) 22-44-46-88 E – mail: okomakoffi@yahoo.fr

3. Centre National de Recherche Agronomique, Laboratoire Central de Biotechnologie. 01 BP 1740 Abidjan 01, Côte d’Ivoire, Tel: (225) 23-45-41-70, Fax: (225) 23-45-33-05,

Abstract

The rubber tree Hevea brasiliensis is an Euphorbiaceous from Amazonian basin cultivated for latex production. The physiological disease, the syndrome of the tapping panel dryness, which causes no latex out-flows, affects this production. The sensitivity of Hevea brasiliensis to this syndrome depends on the clone. To understand the molecular bases of this sensitivity difference, the polypeptides of rubber particles were analyzed with different clones using the two-dimensional electrophoresis technical. The present study highlighted a relation between the clonale sensitivity and the variation of the accumulation of six acidic polypeptides. These polypeptides correspond probably to isoelectric variants of two 14.5 KDa and 26 KDa major proteins. Five among these polypeptides (P2, P4, P5, P8 and P9) were expressed abundantly in the most sensitive clones while the latter (P3) presented a very weak expression among these clones. These polypeptides that fluctuate according to the sensitivity of the clones can beings used as markers for tapping panel dryness sensitivity and serve as tools for precocious selection of tolerant clones.

Keywords: Hevea brasiliensis, tapping panel dryness, sensitivity, rubber particles, proteins, Côte d’Ivoire.

10

Utilization of waste Natural Rubber (NR) gloves for NR based products

Champa Wellappili*, Indra Denawaka*

*Rubber Research Institute of Sri Lanka, Telawala Road, Ratmalana. Sri Lanka

Abstract

The disposal of used and rejected NR gloves is an environment problem. From environmental and economical perspectives, recycling is one of the popular methods for the treatment of waste rubber. However, it is not easy to melt down and mould into new products because the waste gloves are cross linked polymer.

The aim of this study was to find a more economical way of recycling used NR gloves. This was done by using a dispersing agent to give better miscibility. A series of experiments were carried out with two types of blend – namely NR with untreated gloves and fatty acid (FA) treated gloves.

The experimental results indicate that the physical properties and crosslink density were enhanced by the preconditioning of waste NR gloves with FA when compared to blends with untreated gloves. FA seems improve the miscibility of the two phases through possible plasticizing action.

Keywords: dispersibility, crosslink density, pre-treating

11

The Effect of Epoxidised Natural Rubber Content on the Physical Properties of the NR/ENR Blends

M. M. Jayasuriya 1, D. J. Hourston 2, A. Samarakoon 1, S. Yapa 1 and R. Liyanage 1

1 Rubber Research Institute, Telewala Road, Ratmalana, Sri Lanka

2 Loughborugh University, Loughborugh, Leicestershire, LE11 3TU, UK

Abstract

The natural rubber (NR) and epoxidised natural rubber (ENR) blends were prepared by varying the epoxidised natural rubber content and the level of epoxidation. Raw rubber properties including Mooney viscosity and stress relaxation data were determined using Mooney viscometer (MV2000E). High degree of mill break down of the epoxidised natural rubber was evident from the Mooney viscosity data for the NR/ENR blends. The relaxation response obtained from the stress relaxation data was used to predict the compound behaviour of the NR/ENR blends. The relaxation rate decreased with increase of the epoxy content and the level of epoxidation. The physical properties of the NR/ENR blends prepared using ENR with a 60 % epoxidation level significantly improved at 25% ENR content. Chemical interactions between the natural rubber and the epoxidised natural rubber were not evident to a significant level from FTIR spectroscopic data.

12

The Effect of Accelerator Combination of the Curing System on the Physical Properties of the Natural Rubber and Ethylene Propylene Diene Monomer Rubber Blends

M. M. Jayasuriya1, G. D. D. Krishantha1, S. Yapa1, R. Liyanage1 and Y. Piyadasa2

1 Rubber Research Institute, Telewala Road, Ratmalana, Sri Lanka

2 Associated Motorways, Nagoda, Kalutara, Sri Lanka

Abstract

The natural rubber and ethylene propylene diene monomer (NR/EPDM) rubber blends with 50/50 (wt.%) composition were prepared by using different curing systems to improve the ageing properties of the NR/EPDM blends. Cure characteristics and physical properties such as hardness, compression set, tensile properties, and percentage of retention tensile strength were determined. Accelerator combination in the curing system significantly affected the compression set, tear strength and ageing resistance of the NR/EPDM blends. A combination of TMTM (Tetramethylthiuram monosulphide) and CBS (N Cyclohexyl benzothiazyl-2-sulphinamide) was proven as a effective accelerator combination in improving the ageing resistance of the NR/EPDM blends.

Key words: Natural rubber, ethylene diene propylene rubber, curing system, ageing

13

Integrating Tree Crops, Annual Crops and Natural Rubber in an Avenue Cropping System: a Sustainable Soil-Conserving and Poverty-Alleviating Agroforestry Model in the Philippine Uplands

Carlito R. Solera, Rudy L. Galang, Nicomedes P. Eleazar,

And Eugenio A. Alcala

Abstract

This paper highlights the integration of tree crops, annual crops and natural rubber (Hevea brasiliensis) in an Avenue Cropping System (ACS) as a soil-conserving and poverty-alleviating agroforestry technology in the uplands.

In this system rubber trees are planted at a distance of 2m x 3m x 21m. This means that on both sides of the 21-meter wide alley, two rows of rubber trees are planted along the contour line at 2m X 3m spacing. Fruit crops (lanzones, durian, and coconut), food crops and annual crops (banana, corn, and pineapple) are planted in the 21-meter wide alley.

The Avenue Cropping System is an offshoot of the Rubber-based Cropping System (RbCS), a maximum utilization of farm lands, using carefully planned and designed cropping systems with rubber as the dominant tree crop. The RCS showed that rubber planted with the minimum population of 416 trees ( 4 X 6 m. spacing) per hectare together with other fruit, root, and cereal crops could be tapped beginning on the sixth year and with growth and yield performance comparable to rubber trees planted as mono-crops. After the first year of RbCS trial in a one-hectare farm in North Cotabato (2001-2002), the gross income from the intercrops were as follows: cereals - Php24, 500.00; banana – Php25, 000.00; livestock – Php21, 000.00.

However, said figures shall markedly drop after the sixth year when the rubber canopy shall close, minimizing sunlight on large portions of the plantation floor and, in turn, reducing the area for intercrops and livestock. To promote sustainable income from intercrops and livestock, the Avenue Cropping System was developed with rubber trees planted much farther apart than those in the RbCS. Now, there are three six-year-old one-hectare ACS trials in Carmen, Makilala, and Kabacan, North Cotabato.

More small-hold farmers tend to adopt the ACS because it leaves permanent space for raising food crops, and animals; it minimizes soil nutrient loss; and maximizes land income. Besides earning Php120,000.00/hectare/year from growing rubber, the farmer earns from the livestock and intercrops as early as a year after plantation establishment.

In conclusion, the Avenue Cropping System shall sustainably increase the Filipino farmer’s income and rehabilitate the Philippine uplands.

14

Is impeded root growth related to the occurrence of rubber tree Trunk Phloem Necrosis (TPN)?

Preliminary results from NE Thailand.

A. Pierret 1, C. Doussan 2, L. Pagès 3, F.C. Do 4, S. Gonkhamdee 5, J.- L. Maeght 6, W. Chintachao 6, D. Nandris 7

1. IRD-IWMI-NAFRI, UR Solutions, BP 06 Vientiane Lao PDR

2. INRA, Climat, Sol and Environnement, Avignon France

3. INRA Plantes et Systèmes Horticoles, Avignon France.

4. IRD-KKU, UR Clifa, Khon Kaen, Thailand

5. Faculty of Agriculture, University of Khon Kaen (KKU), Thailand

6. IRD-Land Development Department, Chatuchak, Bangkok, Thailand

7. IRD-CEFE, UR Clifa, Montpellier, France.

Abstract

This paper presents the results of a pilot project aimed at unravelling putative links between the occurrence of Trunk Phloem Necrosis (TPN) and impeded root system development in a small rubber tree (RRIM 600) plantation of NE Thailand. To investigate as many root parameters as possible, our methodology included a wide range of techniques: destructive sampling, root mapping, rhizolocation, architectural characterisation of coarse woody roots,and electrical measurements by capacitance and earth impedance. We found that under the environmental conditions that prevail in NE

Thailand, there is no relationship between most of the root parameters we measured and TPN, at least within the first meter of the soil profile. This result contrasts with observations previously made in western Africa. However, we found that at a soil depth of ~25 cm where maximum soil bulk density is generally observed, Healthy (H) trees can grow roots of significantly higher Specific Root Length (SRL) than those affected by TPN. The next phase of this work which is part of a multidisciplinary programme on TPN, will therefore focus on root morphological descriptors such as SRL and on the analysis of the deeper parts of rubber tree root systems.

Keywords: Hevea Brasiliensis, abiotic stress, trunk phloem necrosis (TPN), root architecture, earth impedance method

15

Drought and Trunk Phloem Necrosis (TPN) Effects on Water Status and Xylem Sap Flow of Hevea brasiliensis

Supat Isarangkool Na Ayutthaya1,*, Junya Junjittakarn1, Frederic C. Do2,

Krirk Pannengpetch1, Jean-Luc Maeght3, Alain Rocheteau4, Daniel Nandris4

1. Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand

2. Institute of Research for Development (IRD), Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand

3. Institute of Research for Development (IRD), Land Development Department, Bangkok, Thailand

4. Institute of Research for Development (IRD), Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Montpellier, France.

* Author address for correspondance: isupat@kku.ac.th

Abstract

The aim of this work was to study the effect of a soil drought during the wet season on the water status and xylem sap flow density of mature rubber trees. Part of a wider multi-disciplinary research program, this study distinguished healthy tapped trees and trees affected by Trunk Phloem Necrosis (TPN) to test if the latter differed in their response to a soil water constraint.

The experiment was conducted in a plot of RRIM600, planted at 2.5m x 7.0m spacing and tapped for four years. The plantation is located at Baan Sila, Khu-Muang, Bureerum, a dry area of northeast Thailand with a dry season of five months and an average annual rainfall of 1170 mm. Environmental conditions (weather and soil water content), leaf water potential (predawn and midday values) and xylem sap flow density (transient thermal dissipation method) were monitored from the onset to the core of the wet season in 2007. Three periods of contrasted soil water content and similar ranges of evaporative demand were selected for the analysis of the effect of soil drought: late May (onset of rainy season), late July (soil drought) and early August (recovery).

Our results showed highly significant changes in the predawn leaf water potential (Ypd) and in the maximum density of xylem sap flow during the July soil drought. Maximum density of xylem sapflow was a good indicator of the daily cumulated sap flow, which is closely related to daily tree transpiration. The overall relationship between maximum daily sap flow per sap wood area and Ypd showed a significant positive trend. No significant differences were observed between healthy and TPN trees in leaf water potential and xylem sap flow.

The next step of this work will compare a water constraint in the wet and dry season, and set up an experiment with continuous measurement able to capture a sporadic hydraulic failure related to the water exchange between xylem and phloem.

Keyword: Hevea Brasiliensis, rubber tree, soil drought, Trunk phloem necrosis, water status, xylem sap flow, wet season.

16

An Integrated Method for the Management of White Root Disease in Rubber Plantations in Sri Lanka

K.E. Jayasuriya

Rubber Research Institute of Sri Lanka

Abstract

Approximately 5% of rubber lands in Sri Lanka are infected with the white root disease attributing to low stand and yield. Disease incidence has increased at an alarming rate and hence an economically viable system is essential for the management. Although drenching systemic fungicides successfully controlled the disease in young rubber plants up to 3 years, infections on mature trees were difficult to manage similarly. Collar treatment did not eliminate the fungus from the bark tissues of mature laterals up to sixty days, whereas superficially grown fungus was never affected due to the same treatment. Addition of sulfur to soil in the lateral root zone was effective after four months in suppressing the superficially grown fungal rhizomorphs. Therefore, fungicide treatment integrated with sulfur application around infected trees was successful in managing further spread. In managing the infection in older plantations, fumigation of infected logs using metham sodium was effective in more than 50% of cases, while subsequently adding sulfur to soil enhanced the fumigation effect. Stump poisoning with 2,4-D had a significant effect on the decaying rate of logs in infected areas. For final verification about the viability of the pathogen in vacant holes in the infected area, application of Gliricidia poles was indicative. These integrated methods were effective in synergism in controlling or managing the spread of R. microporus in young and mature infected rubber fields.

17

An insight into laticifers sucrose transporters regulation in

relation with the Ethrel-stimulation of latex yield.

A. Dusotoit-Coucaud (1), H. Chrestin(2,3), P. Kongsawadwoarkul(3), U. Sookmark(3), F.

Granet (4)and S. Sakr(1,5)

(1) UMR 547 PIAF, INRA, Université Blaise Pascal, 24 avenue des Landais, 63177 Aubière

cedex, France

(2) UR 060, Institut de Recherche pour le Développement (IRD), Montpellier, France

(3) Department of Plant Science, Faculty of Science, Mahidol University, Rama VI Road,

Bangkok, 10400, Thailand

(4) Composants Naturels, MFP Michelin, Clermont-Ferrand, France.

(5) Laboratoire Sciences Agronomiques Appliquées à l’Horticulture, UMR INRA-INH-UA,

Angers, France

Abstract

The economic product of Hevea is a rubber-containing cytoplasm, which flows out from laticiferous cells upon bark tapping. It has been known for long that the natural rubber synthesis requires sucrose and that the laticiferous cells are heterotrophic, apoplastically connected to other tissues. These features imply that the rubber yield may depend upon the efficiency of laticiferous cells to load and to use the imported sucrose.

Here, the sucrose transporters were investigated as part of a program aimed at identifying and studying major genes involved in the ethylene-stimulation of the rubber yield. First, seven putative sucrose transporters have been isolated from a late specific cDNA library. Based on their sequence homologies, they belong to three SUT families (SUT1, SUT2 and SUT4). Expression profiling of these sucrose transporters was monitored in the latex from trees of the PB217 and PB260 clones, using real time PCR.

Our data show that they are differentially regulated by ethylene (3 are up regulated, 1 is down regulated and 3 insensitive to ethylene) and this regulation is tissue-specific. To give an insight into the mechanism by which ethylene regulates sucrose transporter expression, their promoters have been cloned and the characterization of their respective activity is on the way in our laboratory.

Keywords: ethylene, Hevea brasiliensis, Hevea clones, latex cells, sucrose transporters.

18

RRIMFLOW System of Exploitation: Assessment of Performance on Renewed Bark

S. Sivakumaran1, Tajuddin Ismail1, F. K. Tham1 and F. C. Tham1

1. Greenyield Berhad, No. 21 & 23, Jalan Seksyen 3/7, Taman Kajang Utama, 43000 Kajang, Malaysia

Abstract

The RRIMFLOW System of Exploitation (RF) has been extensively adopted commercially on both basal virgin (B0-2) and high panels (H0) of various clones in several NR producing countries since it was first recommended for commercial adoption on trees above twelve years of age from planting in the mid-nineties. The RF short cut system is widely accepted as the ideal system to maximize tree, tapper and land productivity in rubber as well documented in several publications. It is however not widely known in the industry that the RF system is equally effective on renewed bark (panel B1-1) provided it is of good quality and sufficient thickness. This paper assesses the performance of the RF short cut system on renewed bark based on data collated from commercial task size evaluation and large scale commercial adoption and determines it’s suitability for wider commercial adoption on panel B1-1.

Data presented has confirmed that the yield responses obtained on renewed panel B1-1 tapped on the RF short cut system are far superior to that of conventionally tapped trees irrespective of clones. This was true for all three parameters of yield namely tree, tapper and land productivity. These yield responses on panel B1-1 exploited on the RF system are comparable if not better than that obtained on panels B0-2 or H0-1. The positive yields obtained from RF exploitation of panel B1-1 also recorded in trees of PBIG-GG2 seedlings tapped on double cuts on panel H0-1 & B1-1. Trees of four clones previously exploited on panel B0-2 on the RF system for periods of 3 to 5 years registered marked increase in yield productivity when the panel was changed over to panel B1-1. The data strongly suggests that RF exploitation of renewed panel B1-1 of most clones is profitable and economically viable. It is also apparent from the data that high yield productivity obtained on the RF system can be sustained over the long term by panel changeover and that renewed bark of panel B1-1 can withstand RF exploitation based on stable DRC values recorded over the long term.

This paper will remove the misleading perception in the industry that the RF system of exploitation is only good for basal panel B0-2 or high panels (H0-1 to H0-4) and not very suitable for adoption on renewed panel B1-1. The RF system of exploitation (1/4s d/3 + gaseous stimulation) is strongly recommended for large scale commercial adoption on renewed panel B1-1 to maximize yield productivity and prolong the economic life of the rubber tree, particularly in view of the prevailing high selling prices of rubber.

Keyword: Hevea brasiliensis, RRIMFLOW, gaseous stimulation system, rubber stimulation, renewed bark.

19

Senevirathna N.D1, Priyanka U. M. S2., Ranjith S. L. G2., Hewage S1, Siriwardena S2.*

1 Department of Chemistry, University of Colombo, Sri Lanka

2 Rubber Research Institute of Sri Lanka. Telewala Road, Ratmalana, Sri Lanka.

Abstract

Two mixing techniques were used to prepare silica slurry incorporating a coupling agent in it for the preparation of silica/Natural Rubber masterbatches incorporating silica at latex stage. In the first technique, silica slurry was prepared in a ball mill by dispersing silica in an aqueous chemical mixture containing a silane coupling agent while in the second technique, an emulsifier equipment was used instead of the ball mill. For the purpose of comparison, NR/Silane treated silica composites were prepared by dry mixing on a two roll mill. The performance of these techniques was evaluated by examining the uniformity of filler dispersion and percentage retention of silica in the masterbatches as the performance indicators. Silica incorporated field NR latex masterbatches were then coagulated and Ribbed Smoked Sheets (RSS) were manufactured according to the standard manufacturing procedure for RSS. The mechanical properties of the vulcanisates prepared on a two mill were then evaluated.

Results of mechanical properties showed that the compounds based on masterbatches prepared by mixing silica slurry made using an emulsifier equipment produce better compounds. Therefore, the emulsifier technique was considered the best mixing technique among the two candidate systems studied.

Keywords: NR latex, silica, emulsifier technique, ballmilling technique

*Corresponding author

20

Genetic Transformation and Regeneration of Plant Over-Expressing CuZnSOD Gene to Control Oxidative Stress in Rubber Tree

J. Leclercq, F. Martin, L. Lardet, M. Rio and P. Montoro*

UMR DAP, Department BIOS, CIRAD, TA A-96 / 03, Avenue Agropolis, 34 398 Montpellier Cedex 5, France.

*To whom correspondence should be addressed

Tel (+33) 4 67 61 56 82

Fax (+33) 4 67 61 55 96

pascal.montoro@cirad.fr

Abstract

Hevea brasiliensis is the main source of natural rubber which is biosynthesized in latex cells. The high metabolic productivity required for latex regeneration after each tapping can be enhanced by ethylene application, which optimizes the production potential in rubber tree. However, excessive metabolism activation can lead to Tapping Panel Dryness (TPD). Expression analyses of many genes involved in detoxifying the reactive oxygen species (ROS) have been studied in healthy trees, TPD trees and also in young budded plants. Among them, the gene encoding CuZnSOD displays a differential expression in the three genotypes and in response to normal photosynthesis occurring during the day, in response to ethylene and wounding in young budded plants.

Indeed, during photosynthesis, ROS production is intense and CuZnSOD gene expression is slightly stimulated in PB260 at 4.00 pm and highly stimulated at 12.00 am in PB217 and RRIM600. In response to ethylene, CuZnSOD gene expression is slightly stimulated in PB260 and PB217 but repressed in RRIM600 even if the expression level is higher. Moreover, CuZnSOD transcript level is reduced in response to wounding. As the CuZnSOD gene has been shown to be also less expressed in tree affected by TDP, it was over-expressed under the CaMV35S promoter in friable calli of the genotype PB260 by an Agrobacterium tumefaciens-mediated genetic transformation using the GFP visual marker. The calli containing one insertion of the T-DNA have been selected and the over-expression of the CuZnSOD gene checked. Plants are now acclimated in the green house and their response to abiotic stress will be analysed.

Keyword: Hevea brasiliensis, genetic transformation, oxidative burst

21

Identification of a Multigene Family Encoding ACC Oxidase in Hevea brasiliensis

Kuswanhadi1, J. Leclercq2, L. Alemanno2, M. Rio2, J. Tregear3, M.-N. Ducamp-Collin4, P. Montoro2*

1 Sembawa Research Centre, Indonesian Rubber Research Institute, Indonesia

2 UMR DAP, Department BIOS, CIRAD, TA A-96 / 03, Avenue Agropolis, 34398 Montpellier Cedex 5, France.

3 IRD UR 192, 911 Avenue Agropolis, 34394 Montpellier Cedex 5, France.

4 UR 24, CIRAD, TA 50/16, 34 398 Montpellier Cedex 5

*To whom correspondence should be addressed

Tel (+33) 4 67 61 56 82

Fax (+33) 4 67 61 55 96

pascal.montoro@cirad.fr

Abstract

Ethylene is a major stimulating factor for natural rubber production in Hevea brasiliensis and is often applied in the form of Ethephon, an ethylene releaser. In a positive feedback type mechanism, the application of ethylene leads to the enhanced expression of genes involved in ethylene biosynthesis such as ACC oxidases, which are also responsive to wounding. We studied the regulation of ethylene biosynthesis in rubber tree through the characterization of the ACC oxidase multigene family and the responses of individual genes to ethylene and wounding. Three full-length cDNAs, HbACO1 (EMBL accession AM743170), HbACO2 (EMBL accession AM743171), and HbACO3 (EMBL accession AM743172) were isolated. All of the HbACO genes were expressed at all stages of development studied, from in vitro callus to the exploited plant, but with different expression profiles (Kuswanhadi et al. 2005). HbACO1 was expressed at a higher level than the other genes, and was down-regulated by ethylene and wounding in both leaf and bark tissues. In contrast, HbACO2 and HbACO3 were transiently induced in response to ethylene and wounding. Treatment with 1-MCP, an ethylene action inhibitor, abolished the ethylene induction of HbACO2 expression, showing that this gene was under positive feedback regulation. The expression of HbACO3 was also induced by ethylene treatment and wounding, again with an antagonistic effect of 1-MCP. In conclusion, HbACO1 appears to be responsible for basal levels of ethylene production while HbACO2 and HbACO3 are up-regulated in response to external factors.

Keywords: Hevea brasiliensis, ACC oxidase, 1-methylcyclopropene, ethephon, ethylene, wounding, latex cell

22

“Budding from Rejuvenated Clones”: a Good Compromise Between Micropropagation and Conventional Budding

M.P. Carron1, F. Granet2, and J. Keli3

1 - UMR DAP 1098 – CIRAD-BIOS, TA A-96/03 6 Ave Agropolis F 34398 Montpellier CEDEX 01 – France - marc-philippe.carron@cirad.fr

2 – Manufacture Française des Pneumatiques MICHELIN - CPN – 23 place des Carmes-Déchaux– F 63040 Clermont-Ferrand CEDEX – France

3 - CNRA, Station de Bimbresso 02 BP 1536, Abidjan 01, Ivory Coast

Abstract

Industrial cloning of the rubber tree is carried out by budding, as the cutting technique is prevented by the very rapid reduction in adventitious rhizogenesis ability during ageing. The juvenile budding or "juvenile type" (JT) was invented by the Dutch at the West Java Experimental Station in 1930: the scion was taken from the stem of young seedlings. Several experiments between 1930 and 1950 revealed the added-value of that type of material compared to the "mature type" (MT) of the conventional budding, which is used even today throughout the rubber growing world.

A Chinese team adapted that "invention" in 1985 to take advantage of the rejuvenation induced by somatic embryogenesis from anther cultures. The few plantlets obtained were used to produce GVPs (buddings from in vitro plantlets). At the beginning of the 1990s, based on those data, the CIRAD team used different horticultural processes and somatic embryogenesis to improve propagation by microcuttings and to produce GVPs from mature selected clones. Field trials with statistical design were conducted as early as 1994 in Ivory Coast, then in Thailand and in Nigeria. That work confirmed the merits of the GVP for budding success, growth and natural rubber production.

However, the development of this new varietal type requires agronomic validation, as the results available, though they tally, come from small-scale field trials. In addition, knowledge needs to be acquired on the conservation of juvenility in rejuvenated clone budwood gardens (JBG). Diversification of selected clones rejuvenated by somatic embryogenesis is also necessary.

Keywords: Hevea brasiliensis, rejuvenation, somatic embryogenesis, phase changes

23

Ethylene induces Lipoxygenase Genes (jasmonate pathway) early

upregulation in the inner bark tissues of Rubber Tree

T. Rotchanapreeda1, P. Kongsawadworakul1, U. Sookmark1, H. Chrestin1, 2

1 Department of Plant Science, Faculty of Science, Mahidol University, Bangkok, Thailand

2 Institut de Recherche pour le Développement (IRD), Montpellier, France

Abstract

Ethylene (Ethrel) is used in rubber plantations to increase rubber yield. Ethylene is a phytohormone involved in regulations of plant growth and development, including stress and defense responses. The effects of ethylene to increase the natural rubber yield have been extensively investigated for its physiological role in the laticifers. However, the molecular events of ethylene action in the inner bark tissues of mature rubber tree have not been extensively studied yet. In this study, we used the Suppression Subtractive Hybridization (SSH) technique to monitor the differentially expressed genes in the inner bark, between ethylene-treated and non-treated (control) rubber trees (2-years tapping). Among the sequenced 2,231-ESTs from these bark SSH libraries (ethylene vs control and control vs ethylene), 55 ESTs, grouped in 4 contigs, identified as at least two different isoforms of plant lipoxygenase, were present in the ethylene-treated specific bark SSH library only (no LOX EST was found in our latex SSH libraries), indicating probable up-regulation of these bark LOX genes in response to ethylene. Lipoxygenases are involved in the biosynthesis pathway of jasmonic acid (JA), a plant regulator involved in plant development and produced in systemic response to wounding and pathogens, thus playing an important role to mediate defense response genes. Results from semi-quantitative RTPCR confirmed that the expression of these lipoxygenase gene isoforms was very low

or undetectable in the inner bark of the control trees, but were transiently markedly induced in Ethrel-treated rubber tree bark only. In the bark, LOX expression was maximum as soon as 4 h and until 8h after the treatment, then decreased progressively from 16 h and return almost to its basic level at 40 h. Using the same specific primers neither any basal expression nor ethylene induced overexpression of

LOX could be detected in the latex, indicating that these LOX gene isoforms were tissue (bark) specific. These results confirm the well-known crosstalk between the ethylene and jasmonate pathways in plant.

Keywords : Ethylene, gene expression, Hevea brasiliensis, Lipoxygenase, SSH library

24

Differential expression of some ASR gene isoforms in the latex and

bark of rubber tree. Effects of Ethrel stimulation.

S. Chatsapsin1, U. Sookmark1, P. Kongsawadworakul1, and H. Chrestin1,2

1. Department of Plant Science, Faculty of Science, Mahidol University, Bangkok, Thailand

2. Institut de Recherche pour le Développement (IRD), Montpellier, France

Abstract

The rubber tree latex yield can be improved through bark stimulation with Ethylene. Ethrel®, an ethylene releaser, induces marked changes in the physiology and metabolism of the latex cells. In this study, the Suppression Subtractive Hybridization (SSH) technique was performed to compare the Hevea latex transcriptomes from control and Ethrel stimulated trees. Preliminary bioinformatic analysis of our 2 latex SSH libraries (Stimulated vs Control and Control vs Stimulated) showed that among the # 2,200 total sequenced ESTs, 3 isoforms of Abscisic acid (ABA) Stress Ripening gene (ASR) were found : 2 ASR1 isoforms and one ASR2. One ASR1 (ASR1-1) was present in both control and stimulated tree enriched latex SSH libraries, while the other (ASR1-2) was present in the stimulated enriched latex library only. In contrast ASR2 was found in the control tree enriched SSH library only. The ASRs are plant-specific stress-regulated gene family with DNA-binding property, whose biological role remains uncertain. In tomato, ASR2 encodes a putative transcription factor likely to be involved in one of the signaling pathways of ABA. The other two members, ASR1 and ASR3 share high sequence identity with ASR2, in which ASR1 has a zinc dependent DNA-binding activity. To investigate the possible role of ASR genes in relation with rubber yield and ethylene stimulation, differential expression of these isoforms of ASRs were studied by semiquantitative RT-PCR. Preliminary results showed that the bulk of ASR1 isoforms were constitutively expressed, at a similar level, in both latex and inner bark, and not

regulated by ethylene, while a specific isoform (ASR1-2) was expressed in the latex only, and not or late slightly down-regulated by ethylene. Our ASR2 isoform was latex specific, being constitutively expressed and significantly down regulated by ethylene in the latex only, but neither expressed nor regulated by ethylene in the inner bark. Based on recent reports on ASR proteins function, we propose a new hypothesis for the ASRs function in the latex cells.

Keywords: ASR genes, ethylene, Hevea brasiliensis, latex, SSH library.

25

Evaluation of the Potentials of Some Economic Vegetable Cover Crops as Live Mulch for Weed Control During The Early Growth of Hevea Sapling in Humid Forest Zone of Nigeria

Okore, I.K., Akpobome, F.A., Okwu, U.N.,Mokwunye, M.U.B. and Eskhade, T.U.

Rubber Research Institute of Nigeria, P.M.B 1049, Benin City.

Abstract

Field experiment was conducted in 2004 and 2005 at the Rubber Research Institute of Nigeria, during the raining seasons. The objective was to evaluate the weed suppression potentials of some commonly grown economic vegetable cover crops (vegetable cowpea – Vigna unguiculata. L. Walp. Ssp. Sesquipedallis, Egusi melon – Cucumeropsis mannii Naud., Fluted Pumkin – Telfairia occidentalis. Hook. F and pumkin – Cucurbita pepo) intercropped with rubber saplings within the first 12 months. These were compared to rubber sole (with Centrosema pubescens). The experiment was laid out in a randomized complete block design with four replications. The weed density was significantly reduced by the vegetable crops with Cucurbita pepo given over 200 and 600% reduction in 2004 and 2005 respectively, relative to rubber sole. All through the period of sampling, sole rubber had a significantly higher average number (12 and 10.2/m2 in 2004 and 2005) of weed spectrum. However the value did not differ significantly from those recorded from rubber / T. occidentalis intercrop. The effect of the cover crops on weed biomass dry weight followed similar trend. The cover crops did not differ significantly on their effect on rubber sapling height and stem girth compared to the rubber sole. It could be said that with the exception of T. occidentalis, the other vegetable cover crops evaluated could be of great importance in the control of weed during the first few years of rubber plantation establishment in the humid tropics.

26

Modification of NR/EPDM/Carbon Black Composites by Co-vulcanization using High Energy g-radiation: Effect of Sensitizer Concentration

S. Siriwardena1*, G. D. D. Krishantha1, D. G. Edirisinghe1, G. M. P. Perera1,

L. Karunanayake2

1 Rubber Research Institute of Sri Lanka, Telawala Road, Ratmalana, Sri Lanka.

2 Department of Chemistry, University of Sri Jayawardenapura, Nugegoda, Sri Lanka.

Abstract

The effect of sensitizer concentration on the mechanical properties of irradiated NR/EPDM/CB (70/30/30) composites was studied. Polyethylene glycol 400 diacrylate (A-400) was used as the sensitizer and its concentration was varied from 0 to 8 phr. The composites were irradiated at 80 and 100 kGy irradiation doses.

Non-sensitized composites irradiated at 100 kGy exhibited better mechanical properties than that of irradiated at 80 kGy except for elongation at break (Eb). However, the composites irradiated at 80 kGy in the presence of the sensitizer showed higher tensile strength and Eb, lower abrasion weight loss and tear strength. Neither irradiation dose nor sensitizer concentration has shown a significant effect on the modulus and hardness of the composites.

The addition of a sensitizer resulted in improvement of mechanical properties except the modulus, until sensitizer level reached an optimum concentration beyond which properties dropped gradually. The optimum concentration of sensitizer to obtain the best mechanical properties of the composites irradiated both at 80 and 100 kGy was found to be 1 phr. Therefore, this concentration of polyethylene glycol 400 diacrylate was considered the best for sensitizing NR/EPDM/CB composites.

Key words: sensitizer, composites, mechanical properties, irradiation, NR/EPDM

*corresponding author: sus_siri@yahoo.com

27

Rubber Learning Centers Oriented by Farmers’ Participation in the North and North-East of Thailand

Pranee Pathanasriskul, Sutat Suravanit and Team*

Rubber Research Institute of Thailand, 50 Paholyotin Road,

Chatuchak, Bangkok 10900.

* Officials from Department of Agriculture

Abstract

This study initiated the concept of farmers oriented; the researchers collected farmers’ problems and needs from farmers’ group meetings. Let the farmers talk, open their mind, learn from their experiences in the farmers’ group meetings and proceed to the certain experimental research in terms of urgent and needed issue in priority. In 2007, 5 rubber learning Centers have been established in Nongkai, Buriram, Sakonakon, Ubonratchathani and Chiangrai Province. In each Center, 10 – 30 farmers’ group meetings had been setting up in certain provinces to collect farmers’ problems; not less than 20 – 50 problems from each province had been arising, subsequently, training courses were requested in tapping and budding. In Nongkai, Buriram, and Chiangrai Province, tapping and budding training courses provided for 537 farmers (leading farmers). Also farmers’ problems from the group meetings had led to set up 2 role model of experimental research projects in each Center consequently namely: role model of rubber plantation follow the King’s efficient economic philosophy; role model of rubber clone trail with appropriate technology management. Solving farmers’ problems by farmers’ participation is planned to continue. We believe that farmers and researchers learn together, the provided technology is finally considered successful.

28

Technology Adoption in Indonesian Rubber Smallholding Sector

M. Supriadia, Laxman Joshib and Gede Wibawac

a) Indonesian Rubber Research Institute

b) World Agroforestry Centre (ICRAF)

c) Indonesian Research Institute for Estate Crops

Abstract

Natural Rubber (NR) contributes significantly to the Indonesian economy both as a primary source of income for millions of rubber farmers and also as a source of foreign exchange. In 2006, with total exports of around 2.6 million tonnes, rubber earned around US $ 4 billion or more than 40% of the total estate crops exported from Indonesia. NR is also the principal source of cash income for more than 10 million people. Rubber plantation in Indonesia is dominated by smallholding (plots of 5 ha or less) sector (84% of total rubber area) that produce around 1.8 million tonnes or 81% to the national NR production.

There are some crucial problems faced by rubber smallholders in Indonesia. Compared with the large estate plantations, rubber yield and productivity of rubber smallholdings are very low. The state and private plantations have annual average yield of 1,039 kg DRC/ha and 1,202 kg DRC/ha respectively, while smallholdings productivity in 2005 was about 796 kg/ha. This low productivity can be attributed to the fact that majority of Indonesian smallholders still practice the traditional Jungle Rubber (JR) system in forest like environment. So far only 18% smallholdings have adopted the recommended rubber technology and managing their plantations intensively.

To improve the rubber smallholding sector, the Indonesian government has implemented numerous rubber development programs and projects in the past. The government is now promoting rubber replanting in old rubber plots with recommended rubber technology. This paper describes the current level of technology adoption by rubber smallholder farmers in Indonesia; and efforts carried out by research for development institutions. Data were collected from four rubber producing provinces in Indonesia i.e. South Sumatra, Jambi, West Sumatra, and West Kalimantan.

Keywords: natural rubber, rubber smallholders, productivity, replanting program, jungle rubber

29

Latex Foam and Rubberized Coir: Appropriate Technology for Developing Rural Small-Medium Scale Rubber Based Industry

Uhendi Haris, Dadi R. Maspanger, Maurits Sinurat

Bogor Research Center for Rubber Technology - Indonesian Rubber Research Institute

Jalan Salak No. 1 Bogor 16151 Indonesia. E-mail: bptkbgr@indo.net.id

Abstract

Indonesia produced 2.6 million tons of natural rubber in 2006. The domestic consumption is estimated 13% from the total national production. This domestic consumption is mostly absorbed by tyre industry, latex goods industry, and industrial rubber goods. These industries generally developed around cities and do not have direct linkage with smallholder rubber as a dominant producer of natural rubber, neither functionally nor spatially. Natural latex based industry with appropriate processing technology as well as machineries has an opportunity to be developed in small-medium scale in rural areas. Bogor Research Center for Rubber Technology (BRCRT) has developed several pilot plants in farmer group level at smallholder rubber production center in Kalimantan. The type of industry that has been developed was latex foam and rubberized coir with consideration that main raw material for production process is available locally. Equipment and processing technology were designed by BRCRT to meet the needs of small-medium industry in villages. The establishment of pilot plant and smallholder empowering were carried out through cooperation between local government and BRCRT. Pilot plants of latex foam were built at two locations namely South Kalimantan and Central Kalimantan. Meanwhile, pilot plants of rubberized coir were built at East Kalimantan and South Kalimantan. According to BRCRT experience, the implementation of appropriate technology for developing rural small-medium rubber based industry often facing several constraints. The main problem that rose was not related to machinery performance, either from construction side or operational technique. The problem that relates to production technique was relatively easy to overcome, that can be done through intensive training or guidance by technology supplier in production process. The main constraint was relates to capital, condition of human resource, and marketing management. The availability of fund to become initial capital, which return has to wait until products are sold often becomes a constraint. In this problem, marketing become important factor for the continuity of production process. Without support from marketing aspect with sufficient expertise, farmer group as implementing institution of pilot plant still find difficulties to market their product. Real support from local government or related institution will be very helpful to solve the problem. Support can be present as financial help that can be used as initial capital, intensively coordinate and manage the farmer group, and also hold an active role to market the product.

Keyword: natural rubber, latex foam, rubberized coir, appropriate technology

30

Using Geographic Information System (GIS) to investigate Natural Rubber Yield (Hevea brasiliensis) in Conjunction with Soil Fertility: a Case Study from Cam My Rubber Plantation, South-Eastern of Vietnam

Binh Thanh Nguyen 1,2, Hai Hoa Thien1, Thanh Van Tran2

(1) Department of Agro-chemistry and Soil Sciences, Rubber Research Institute of Vietnam, 177 Hai Ba Trung, district 3, Ho Chi Minh city – Vietnam.

(2) Department of Crop and Soil Sciences - Cornell University, Ithaca, New York 14850, USA

Email address: btn4@cornell.edu or nguyenbinhthanh@yahoo.com

Correspondence: Nguyen Thanh Binh

Department of Agro-chemistry and Soil Sciences, Rubber Research Institute of Vietnam, 177 Hai Ba Trung, district 3, Ho Chi Minh city - Vietnam

Abstract

Soil fertility and the response of rubber yield to changes in soil nutrient contents are the key determinant of fertilizer management. However, yield response of rubber tree at different tapping stages to individual nutritional elements on a basaltic soil in eastern south of Vietnam is little known. In the current study, GIS spatial analysis technique was used to examine rubber yield in conjunction with soil nutrient contents in Cam my rubber plantation, eastern south of Vietnam. Soil samples and latex yield were randomly taken from 4192 ha of the plantation. Latex yield of the middle group, tapping ages from 4 to 9 years, highly responded to soil organic carbon (SOC), total nitrogen (Ntt), total phosphorus (Ptt), total potassium (Ktt), available P (Pavai) and exchangeable potassium (Kex), while yield of the mature group, tapping ages from 10-20 years, significantly responded to SOC, Ntt, Ptt and Pavai. For both groups, all those nutritional elements, except Ktt and Kex for rubber in middle group, however, were in adequate or high levels of contents. For rubber trees in middle group, about 1390 ha (33 %) and 1475 ha (35%) out of total 4192 ha in the plantation were deficient in Ktt and Kex, respectively. The response to increasing soil nutrient content of middle group was greater than that of the mature group, suggesting that nutrient demands of the young tapped trees were higher than those of the old tapped trees.

Keywords: GIS, spatial analysis, soil, fertility, rubber, Hevea brasiliensis, yield, Vietnam.

31

Studying Effect of Potassium Fertilizer to Latex Yield on Grey Soil

Hoa Thien Hai, Tong Viet Thinh

Fertilizer and Soils Division, RRIV

Abstract

This experiment has carried out from 2005 to 2007 on the Grey soil in the Southeast of Vietnam. The experiment consisted of 2 factors and was laid out in split plot design with 4 replications in which 5 levels of potassium were studied in accordance with and without ethephon stimulant.

Based on collected data, some results were obtained as follows:

· Potassium fertilizer had effected to the latex yield after 2 years of application. The latex yields between high level of K and the null control were significantly different. After 5 months average yield of fertilizer treatments increased from 6-9% in comparison to the control.

· Latex analysis results showed that: Pi contain tend to increase proportionally to K levels; In contrast, Mg content tends to decrease according to the raising of K levels. Mg content from the control gave the significantly different in comparison with the highest K level.

· Applied K fertilizer and foliar K content had close relationship.

32

Early Selection 0f IRRDB’81 x W Clones for Resistance to

Oidium Leaf Disease

Lai Van Lam, Le Mau Tuy, Le Hoang Ngoc Anh and Vu Van Truong

Rubber Research Institute of Vietnam

Abstract

The Oidium leaf disease assessment were made on Early Selection Trials (ESTs) of RRIV hand - pollination programs 2000 - 2003. There were 1,267 progenies from Wickham female parents PB 260 and RRIC 110 crossing with 14 clones IRRDB’81 as male parents involving in the study. The evaluation of the disease was discussed based on disease incidence and GCA effect for the disease.

The result showed that difference in susceptibility between two groups IRRDB’81 and W, WA progenies. Many progenies derived from IRRDB’81 male parents had low infection to the disease while those of other male parents had high susceptibility. It was noted some resistant progenies of IRRDB’81 male parents RO 44/268 and RO 44/71. Significant differences in GCA estimates were found for Oidium susceptibility. Most IRRDB’81 male parents showed low GCA values for Oidium susceptibility. The results suggest that there is potential of IRRDB’81 germplasm in breeding program for resistance to Oidium leaf disease.

Key words: Oidium disease, IRRDB’81 Hevea germplasm, resistance, breeding.

33

Modifications/Additions for the International Tapping Notation

Dr. K.R. Vijayakumar

IRRDB Liaison Officer (Exploitation Technology)

Director, Rubber Training Centre,

Rubber Board, Kottayam-686 009, India.

Abstract

It is long time since the international tapping notations were revised. After the last revision, lot of new developments have occurred in the field of exploitation technology. Further revision was suggested in International Workshop on Exploitation Technology that was held in December 2003. Gaseous stimulation is an example. It is felt that rainguarding may also be included in tapping notation. Suggestions for additions/ modifications are presented.

34

Improvement of Storage Stability of Pre-vulcanized Natural Rubber Latex Concentrates for Commercial Applications

W.M.G. Seneviratne#*, Priyanthi Perera*, D.G. Edirisinghe* and Dilini Seneviratne*

* Rubber Research Institute of Sri Lanka, Telewala Road, Ratmalana, Sri Lanka

# Corresponding author

Abstract

An important part of latex product manufacture is that the part or pre vulcanization of Natural Rubber (NR) latex in the liquid state and subsequently used to form a deposit of vulcanized rubber on the former prior to heating for complete cure. Drying of the latex article made out of pre-vulcanized lattices is sufficient to achieve a vulcanized product with physical properties that are satisfactory for many purposes. Pre-vulcanized latex has many applications such as dipped and cast goods, rug backing, coatings and the combining of coir, paper and fabrics. State of vulcanization is quite important in pre-vulcanized lattices. However due to the residual vulcanizing ingredients and other factors such as temperature results in poor stability during storage. Hence an safer and advanced technology is essential to prepare pre-vulcanized latex with long term storage stability. This paper describes certain developments carried out to prevent over vulcanization and thereby improve storage stability of pre-vulcanized latex.

Even when latex is pre-vulcanized, it retains its original fluidity and general appearance of centrifuged latex. The cure takes place in the individual latex particles without altering their state of dispersion. The state of cure of pre-vulcanized latex can be determined by the spot chloroform coagulation test subsequent to the confirmation by the Modified Swollen Diameter test.

Excess compounding ingredients which may retain after pre-vulcanization cause further formation of primary linkages between the latex particles and such lattices would become unsuitable for product manufacture.

Three different processing methodologies were used to study in the preparation of pre-vulcanized lattices in this research work with a view to achieve long term storage stability. Latex quality parameters such as alkalinity, TSC, DRC, VFA and storage stability of pre-vulcanized latex (by testing MST and viscosity) were tested weekly and state of cure was determined twice a week to ascertain the level of pre-vulcanization.

The results revealed that the one of the methods (technique 1) yields the best stability compared to the others and the as per technique 1 exhibited excellent tensile strength and tear strength in comparison with the other methods studied.

Keywards: Natural rubber latex, pre-vulcanization, storage stability, latex quality parameters, strength properties.

35

Vulnerability of Hevea Seed Production to Climate Change: Results of a Survay Done In Intermediate and Wet Zones of Sri Lanka

N.M.C. Nayanakantha* and P. Seneviratne

Rubber Research Institute of Sri Lanka, Dartonfield, Agalawatta, Sri Lanka

Abstract

According to general consensus, seed production of rubber (Hevea brasiliensis) had been satisfactory and well above the requirement of nurseries till the late 1980’s in the Wet and Intermediate Zones of Sri Lanka. However, after late 1980’s there were many complains specially from the nurserymen in the wet region of Sri Lanka that there is a shortage of seed production. Possible reasons which may have contributed to this could be the changes in weather patterns, change in clones planted and disease incidence. Thus, a survey was done on Hevea seed production during 2003 and 2004 in selected rubber plantations in Kurunegala and Kalutara districts representing Intermediate and Wet Zones of Sri Lanka with respect to annual rainfall distribution. Results of the study show significant differences in the production of seeds between Agro-climatic regions, among clones and also in the time periods (2003 and 2004). A significant higher seed production was observed in all three clones (RRIC 100, PB 86 and RRIC 121) irrespective of their age groups in the Intermediate Zone than in the Wet Zone. However, clonal and age effects were also existed in both zones and significantly a lower seed production was existed in 2003 than in 2004. RRIC 100 produced a higher number of seeds per hectare in both zones at both age categories in both the years. RRIC 121 produced the lowest seed production in both the zones irrespective of the age. In the Wet Zone, a considerable seed production was observed in RRIC 100 in the old age category only. This regional difference can mainly be attributed to direct and indirect influences of climatic differences. Among the climatic factors, rainfall has a direct impact on seed production from flowering up to seed fall. Although a significant increasing or decreasing trend in the total rainfall in each year in Kalutara district of the Wet Zone could not be identified for the last 30 years, variations in onset and ending of rains in South West and North East monsoons and also inter monsoonal periods and uneven distribution of rainfall in each month have been observed from 1990-2004. This variation in rainfall pattern might have contributed greatly either directly or indirectly on Hevea seed production although the other climatic factors, disease conditions and clones have cumulatively contributed to the lower seed production in the Wet Zone of Sri Lanka.

Key words: Seeds, Hevea, rainfall, climate, Intermediate Zone, Wet Zone

* Corresponding author’s e-mail: chamilna@sltnet.lk

36

Construction of Rubber Exploitation System

for Shortened Economic Life: Expex-315

Sumarmadji and Karyudi

Sungei Putih Research Centre,

Indonesian Rubber Research Institute

Abstract

Recently, larger world rubber demand and better price potentially support Indonesia. Problem is still be faced such as low productivity and efficiency, claim of increased labor pay, difficulties on skilled tappers, security disturbance, much more complicated of social dynamics, and characteristic of perennial crop cultivation which long term cycle with long immature period as well. A strategy to improve rubber exploitation system based on technological components resulted from research to be adopted by planters. The technological components are high yielding clones with pattern of shorter cultivation, clone classification based on latex metabolism, latex diagnosis, upward tapping system which suitable with source-sink mechanism, technique of tapping panel dryness, and task management which support productivity of both tapper and plant. An objective of these trials was to construct an alternative technology of rubber plant exploitation system that was easy and safely with shortened economic life. The trial target was technological package viz. EXPEX-315 exploitation system with benefit strength such as 34%-shorter of economic life (18 years), 35 tons rubber yield per cycle, no impact on tapping panel dryness, no absolutely need skilled tappers, no increase in risk of production loss, and high quality timber product. An expected economic impact was to increase productivity around 28% with economic cycles just 18 years

The trials were carried out in Sungei Putih Experimental Garden and North Sumatra rubber estates for 3-5 years and start in 2005. Research activities were conducted simultaneously viz. 1) Study of exploitation systems, 2) Analyzing of nutrition need of rubber plant, and 3) Constructing and testing of tapping equipments. It is also necessary for determining of physiological criterion of tapping mature. First and second activities would be done for 3 to 5 years, whilt the third activity would be done for 3 years. Treatments of first activity were exploitation systems viz. 1) Mc15↑ d/3.ET2.0%Ba0.5.9/y.9m/12(m), 2) Mc15↑ d/3.ET2.5% Ba0.5.6/y.6m/12(m), and 3) ½ S↑ d/3 (control) with PB 260 clone. Treatments of second activity were recommended fertilizing of immature plant with 100%, 115% and 130%, with PB 260 clone of 3.5 years old and exploitation system namely Mc15↑ d/3.ET2.0%Ba0.5. 9/y.9m/12(m).Exploitation during the first 2 months was done without stimulant application. Treatments of third activity were constructing and testing on tapping knives manually (low, medium, high) and mechanically for upward micro (10-15 cm) tapping on rubber stand variation. Generally, variables observed were rubber growth, latex production, dry rubber content, duration of latex flow, tapping panel dryness, content of sucrose, inorganic phosphates, thiols, macro/micro nutrients, quality of bark excising, standard performance of tapping by new equipments, and other physiological variables.

The novel exploitation system of EXPEX-315 was expected to provide some benefits in rubber plant cultivation, mainly in increasing productivity with shorter economic life and in providing the rubber timber with high quality. The technology was supported by constructing of tapping equipments (manual or mechanical knife) in order to increase upward tapping effectiveness. Manually, it needs 3 kinds of tapping knife, namely ‘bottom’ knife, ‘middle’ knife’ and ‘above’ knife. This activity was also to design a mechanical knife which has wider capability to support exploitation system of EXPEX-315. The activity has been generated manual tapping knives namely Cungkit-SP, Sliver-SP and short Pacekung knife and a mechanical knife namely GjreG-SP for technology package of EXPEX-315. By the second year activity, data concerning EXPEX-315 exploitation system with other treatments of extra fertilizing, showed no significantly difference on growth variables (stem girth and stem thickness), dry rubber content, duration of latex flow and physiological variables (content of sucrose, content of inorganic phosphate, and content of thiol). In this period, rubber production on treatment of micro upward tapping (Mc10↑ to Mc15↑) progressively increased but still lower than control tapping (1/2 S d/3). However, on variable of production index, treatment of micro upward tapping was significantly higher than control tapping. That mean was basically potential for the exploitation system of EXPEX-315 to improve rubber productivity on the next period. By modifying the main exploitation system from Mc10↑ d/3.ET2.0%Ba1.0.9/y. 9m/12(m) to Mc15↑ d/3.ET2.0%Ga1.0.9/y.9m/12 (m), latex production significantly increased as high as the control tapping. Further modification to Sc20↑ d/3.ET2.0%Ga1.0.9/y.9m/12 (m) was higher rubber yield than tapping control, guaranteeing high rubber productivity in shortened economic life.

Keywords: Rubber plant (Hevea brasiliensis), exploitation system, economic life

37

The Role of Myanmar Rubber Planters and Producers Association (MRPPA) in Natural Rubber Development and its Recent Activities

Hla Myint

Advisor, Myanmar Rubber Planters and Producers Association

(Former Director, Applied Research Centre for Perennial Crops, Myanmar Perennial Crop Enterprise)

Abstract

Myanmar Rubber Planters and Producers Association (MRPPA) has been formed in March 2005. Since then, it has also become an affiliated association of the Union of Myanmar Federation of Chambers of Commerce and Industry (UMFCCI). It is a non-governmental organization (NGO) and comprises of the members of local rubber planters, processors, traders and exporters and end-product rubber goods manufacturers. The main objectives of the Association are to accelerate the overall development of natural rubber planting and manufacturing industries with emphasis on the private sector, for the interest of the persons involved and to contribute to the economy of the country.

Since formation, it has been actively involved in the promotion of rubber trade and export through participation in the trade fairs and exhibitions both locally and abroad and through discussion meetings with visiting trade delegations and missions in cooperation with UMFCCI and the Directorate of Trade (DOT) of the Ministry of Commerce. In cooperation with Myanma Perennial Crop Enterprise (MPCE) under the Ministry of Agriculture and Irrigation (MOAI) and with local authorities of the regions, it also involves in the efforts for the accelerated expansion of rubber planting areas, the use of high yielding cultivars and the adoption of correct planting, maintenance and exploitation techniques. As and when necessary, useful suggestions after consulting with the advisors of the Association are also given to concerned ministries and government agencies. Sharp increases in the planting areas and also in the production and export have been achieved in a short time. With the full support of MPCE, the Association managed to get the full membership status of the International Rubber Research and Development Board (IRRDB) in November 2006. As a member of IRRDB, MRPPA together with concerned local agencies would be able to cooperate and participate in the R & D activities of IRRDB and its member institutes and the acquired experiences and knowledge and the updated information continuously received would in the long-run contribute to the accelerated development of the country’s natural rubber planting and manufacturing industries.

There are many critical issues to be further resolved for the accelerated development of natural rubber in Myanmar. In the coming years MRPPA will focus on the improvement of productivity and quality of the produced rubber and the support for the development of rubber goods manufacturing sector. In this regard, MRPPA will also endeavour to have closer cooperations with local government agencies and also with IRRDB and its member institutes.

Keywords: Rubber, association, trade promotion, market information, technology dissemination.

38

Preliminary Yield Potential Comparison on ½ S d/3 and ½ S d/4 Tapping Systems of Some Hevea Clones in Cambodia

S. Mak 1, S. Hav1, C. Chhek1 and R. Lacote2

1.CRRI, # 09, PennNouth Blvd, Boeung Kak 1, Tuol Kork, Phnom Penh, Cambodia, P.O Box: 1337

2. Cirad, UR 34, Tree Crop Based Systems, TA /B34, 34398 Montpellier, France

Abstract

The experiment on Preliminary Yield Potential Comparison on ½ S d/3 and d/4 Tapping Systems of Some Hevea Clones in Cambodia was on farm research at Chup Rubber Research Station of Cambodian Rubber Research Institute (CRRI). The objective of the experiment was to investigate the preliminary yield potential comparison of the tapping system ½ S d/3 7d/7 and ½ S d/4 7d/7based on frequency of ethephon stimulation. The result for first year, revealed that clone IRCA 111 and PB 330 produced high yield in ½ S d/4 7d/7. ET 2.5%. Pa.4/y. Clone GT1 produced high yield ½ S d/3 7d/7. ET 2.5%. Pa.8/y. Clone IRCA 230 produced high yield in ½ S d/4 7d/7. ET 2.5%. Pa.12/y in Cambodian condition.

Keywords: Hevea, clone IRCA 111, PB 330, GT1, IRCA 230, yield potential.

39

Preliminary evaluation for the application of ethylene gas stimulation (RRIMFLOW) in Hainan State Farm, China

Bai Xianquan1, Jiang Jusheng1, Liu Zhiwei1, Yi Jiexiang1, Lin Yunping1,

Xiong Daiqun1, Tham Foo Keong2, Albert Chua2 and S. Sivakumaran2

(1 Sci-Tech Innovation Center of Hainan State Farm, China

2 GIM Triple Seven SDN BHD, Malaysia)

Abstract

RRIMFLOW (RF) exploitation technique was first introduced in 2006 for purpose of studying the performance of the system under conditions prevailing in Hainan State Farm before embarking on large scale commercial adoption. Eight farms chosen for evaluation of RF system are located on different places in whole Hainan State Farm. And the three clones, RRIM600, PR107 and Haiken6 are chosen for the assessment. The RF system produces higher tree productivity ranging from 10% to 69% over the conventional tapping systems of (S/4+S/4↑)+ET or S/2+ET. It is recorded that generally there is a decline in DRC values of RF tapped trees relative to that of control trees. The clone, age and site environment of rubber trees are contributed to the yield response to RF. RRIM600 and PR107 are good responders, while Haiken6 shows lower response to the system. The older trees increase higher in yields than that of younger trees.

Key words: Ethylene gas simulation, RRIMFLOW, Latex yield

40

Studies on the Compound Ecosystem Balance and Evolution of the Natural Rubber Industry in Hainan of China

Xiong Daiqun1’2, Jiang Jusheng2* Wang Qunhui1, Mai Quanfa2,

Bai Xianquan2, Jia Xiaoying, Liu Zhiwei2

1. School of Civil and Environmental Engineering, University of Science and Technology Beijing,

30 Xueyuan Road, Haidian District, Beijing City, China

2. Research & Development Center of Science & Technology, China Hainan Rubber Industry group Co., LTD, 13 East Haixiu Road, Haikou City, Hainan Province, China)

Abstract

Logistic model was applied to calculate the ri and Ki which are intrinsic activity and environmental tenability in various stages of development of Hainan natural rubber production systems respectively. It was pointed out that the three main factors of sustainable development were ri, Ki and I (co-evolution ability of system). The curve characteristics of dynamic equations

was combined to analyze system change of the first two stages, and the result coincided with actual development of system, which illustrated that the interaction between advantageous factors and limited factors affected the transformation of systematic stabilization and development. It was concluded that early in the third stage of Hainan rubber product system the bottleneck of systematic development was the paradox between operation mechanism of production system with market competition mechanism of service system. Based on the discussion of co-evaluation ability, the suggestion was given out to reform the system in order to promote the sustainable development of Hainan natural rubber production.

Keywords: dynamic equation, advantageous factors, limited factors, intrinsic activity, environmental supported capacity, systematic co-evaluation ability.

41

The Effect of Weeding and Fungicide Treatments on the Development of Corynespora Leaf Fall Disease in Rubber

A. Situmorang1, H. Suryaningtyas1

1. Sembawa Research Centre, Indonesian Rubber Research Institute, P.O Box 1127 Palembang 30001, Indonesia, Email: irr-sbw@mdp.net.id

Abstract

Corynespora leaf fall, caused by the fungus Corynespora casiicola, is one of the most important diseases of Hevea brasiliensis in many natural rubber-producing countries, including Indonesia, Sri Lanka, Thailand, Malaysia and some African countries. Many large-scale recommended clones planted in big estate as well as smallholdings have been severely affected by the disease. The disease caused leaf defoliation throughout the year, hence the plant growth is retarded, the plants never come to maturity and some of them died and they had to be uprooted. The occurrence and development of CLFD is influenced by environmental factors, including mainly humidity, rainfall and air temperature. This part of CFC Corynespora project was carried out to investigate and/or verify whether weeding and fungicide treatment or their combinations could reduce the disease incidence and development in rubber plantation as it has ever been reported based on practical experience by Indonesia Goodyear Plantation in North Sumatra. The results of two years research revealed that weeding and/or fungicide application and their combinations gave no significant influence on the occurrence and development of Corynespora leaf fall disease.

Keyword: Hevea brasiliensis, Corynespora casiicola, control, natural rubber, herbicide, fungicide spraying

42

ScFv Antibody Specific to Cassiicolin, a Host-Selective Toxin of Corynespora cassiicola

E. Sunderasan1#, Rusni A. Kadir1,2, Valerie Pujade-Renaud3,

H. Y. Yeang1, Sheila Nathan2

1. Biotechnology Unit, RRIM Research Station, 47000 Sungai Buloh, Selangor D.E.

2. Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43000 Bangi, Selangor D.E.

3. CIRAD TA 80/03, Avenue Agropolis 34398 Montpellier Cedex 5 France.

#Corresponding author.

Abstract

Corynespora cassiicola leaf disease is a serious threat to rubber trees; the fungus infected leaves develop necrotic lesions and abscind, leaving the tree unproductive. The destructiveness of C. cassiicola has been largely attributed to cassiicolin, a host-selective protein toxin secreted by the fungus. Recombinant antibody technology offers hope to curtail the disease; single chain variable fragment (scFv) specific to cassiicolin could bind and deactivate the toxin in genetically modified rubber trees that harbour the antibody gene. Anti-cassiicolin scFv phage library was constructed from cassiicolin immunized Balb/C mice spleen IgG heavy and light variable chains. Biopanning of the phage library yielded a scFv clone with high specificity to cassiicolin. The nucleotide sequence and deduced amino acid sequence information of the scFv were obtained. The hemagglutinin (HA) tagged scFv expressed in Escherichia coli is discerned as a band at circa 30 kDa on SDS-PAGE. The corresponding band was detected by anti-HA IgG on a Western immunoblot of the gel. Deactivation of cassiicolin by the scFv was demonstrated by leaf bio-assay on PB 260, a susceptible clone. Leaf bioassay is in progress to evaluate deactivation of cassiicolin on the other susceptible clones that are also amenable for genetic modification i.e. GL 1, RRIM 600 and RRIM 2020.

Keywords: Corynespora cassiicola, cassiicolin, anti-cassiicolin scFv, Hevea leaf bioassay

43

Disease Scenario of the Rubber Tree: History and Current Status

C.K Jayasinghe*

*IRRDB Liaison Officer for the Plant Protection Specialist Group, Rubber Research Institute of Sri Lanka , Agalawatta , Sri Lanka

Abstract

Majority of the rubber diseases which were considered as economically important until recent past have been recorded with the beginning of the 20th century. Since then more than 40 significant diseases have been discovered and most of these diseases have a world wide distribution today.

However, since the latter part of the 20th century there was a changing scene in the maladies of the rubber tree. This is mainly due to the production of the resistant clones to common diseases and well acceptance of the new genetic materials by the growers. At the same time some of these breeds together with traditional clones succumbed to new diseases threatening the world’s natural rubber industry. Other factors which contributed to the spread of new diseases were the expansion of rubber cultivation to the new localities and non adoption of correct cultural practices by the growers. This presentation addresses the above issues and discusses the draft document prepared for the IRRDB website on the diseases of current interest.

Key words: rubber diseases, rubber pathogens, website on rubber diseases.

44

Some Considerations Concerning the Yield Potential of Some Clones (Hevea Brasiliensis)

R. Lacote1, O. Gabla2 S. Obouayeba3, E. Gohet1, A. Doumbia2, M. Gnagne3, and K. Dian2

1: Cirad, UR 34, Tree Crop Based Systems, TA B/34, 34398 Montpellier, France

2: Hevego, Rubber Research Station BP 793, San Pedro, Côte d’Ivoire

3: CNRA, 01 BP 1536 Abidjan O1, Côte d’Ivoire

Corresponding author: R. Lacote, regis.lacote@cirad.fr

Abstract

The present study deals with the comparison of stimulation strategies on fourteen clones tapped in 1/2S d/4, over a total period of seven years, in Côte d’Ivoire. For all clones, ethephon stimulation strongly influenced the cumulated yield and the physiology of the latex cells. The responsiveness to the long term stimulation, over seven years, depends on the clonal latex physiology. Ethepehon stimulation is more efficient for clones with a low metabolism. The capability of trees to produce more under ethephon stimulation is related to the sucrose content, which is a clonal characteristic. The gain of the latex yield per clone, related to the physiological characteristics of the latex, can be used to define the yield potential of each clone. The limits of the use of stimulation can be enlarged with clones having higher sucrose content. In that case, it will be easier to increase the yield potential by using hormonal stimulation.

Keywords: Hevea brasiliensis, stimulation, latex physiology, clone, yield potential.

45

Preliminary Characterization of Organic Compounds Caused

Malodor of STR20 Industry

Somtip Danteravanich1, Sunida Yonglaoyoong1, Porntip Sridang2,

Suwaluk Wisunthorn3, and Pimpimol Penjamras4

1. Faculty of Technology and Management, Prince of Songkla University, Surat Thani Campus, Muang, Surat Thani, 84100 Thailand.

2. Faculty of Engineering, Prince of Songkla University, Hat Yai Campus, Hat Yai, Songkhla, 90112 Thailand

3. Faculty of Arts and Sciences, Prince of Songkla University, Surat Thani Campus, Muang, Surat Thani, 84100 Thailand

4. Scientific Equipment Center, Prince of Songkla University, Central Academic Administrator Bld., Hat Yai campus, Songkhla 90110 Thailand.

Abstract

The characterization of organic compounds caused malodor in STR20 (Standard Thai Rubber 20) industry was determined in this study in order to provide the information for the further air pollution management efficiently. The organic compounds were characterized from samples obtained in the laboratory and from the STR20 factory. The samples from laboratory were cuplump water extracted and emitted gases from cuplump drying in experimental dryer while the samples from the STR20 factory were the exhausted gases from rubber dryer and outlet gases from wet scrubber, condensate, and cuplump washing wastewater. The characterization was identified by using gas chromatography coupled with the mass spectrometry (GC-MS) and the concentrations of volatile fatty acids (VFAs) in terms of acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid and isovaleric acid were determined by gas chromatography (GC). The results were illustrated that 25 organic substances were

determined. The dominant organic substances found in all samples were acetic acid, butyric acid, isovaleric acid, hexadecanoic acid, oleic acid, and oleic acid methy ester. It was found that some numbers of found organic substances were reduced and some other new comers were observed during the production processing in STR20 factory. Although the wet scrubber system has been used in STR20 factory to remove volatile organic air pollutants from the exhaust gases from rubber dryer, it was found that it could not remove all volatile fatty acids emitted from cuplump drying. This was because of the appearance of insoluble volatile fatty acids in the emitted gases from cuplump.

Keywords: Air pollution, characterization, malodor, organic compounds, volatile fatty acids, STR20 industry.

46

Reverse Engineering of Rubber and Rubber Products

Faridah H.A.H and Roslan Othman

Materials Characterisation Unit, Malaysian Rubber Board (MRB)

260 Jalan Ampang, 50450 Kuala Lumpur

Abstract

Many a times when products fail to meet the specification and when exact repetition of a competing product is required for manufacturing purposes, one will consider subjecting the product to reverse engineering work where the process often involves taking something apart and analyzing its workings in detail, in order to reveal the full formulation of certain products or rubber goods. The revelation in terms of chemical formulation can be carried out to a certain accuracy and precision by subjecting the rubber samples to laborious chemical analyses that are often complex and time consuming.

Despite its complexity, this paper will tend to elaborate on the chemical aspect of reverse engineering in solving three different types of problems and enquiries brought forward to Malaysian Rubber Board (MRB) by rubber product manufacturers for purposes of analyzing the composition of a molded rubber sample as well as in unraveling product formulation and disclosure of materials of manufacture for screening purposes.

Keywords: Reverse engineering, composition of a rubber product, product formulation, disclosure of materials of manufacture,

47

Assuring Quality, Efficiency and Productivity of the Rubber Product Industry

N. Mustapha, M.R. Nur Salwanie and A.B. Othman

Department of Technology and Engineering, Malaysian Rubber Board, P.O.Box 10150, 50908 Kuala Lumpur, Malaysia

Phone: +603-61561121, Fax: +603-61564418

Email: mustapha@lgm.gov.my

Abstract

The liberalisation of world trade through AFTA and WTO creates a competitive rubber product market. The readiness to meet the challenge is the key factor for survival.

On the raw rubber scene, besides a good and right choice of incoming raw materials and processing equipments, testing and quality control together with a sound factory management system is necessary in order to be amongst the consistent and reputable premium quality NR producers and suppliers. The participation in the Interlaboratory Test Program (or round robin) would ensure added confidence to the buyer of the quality of raw materials produced.

Stringent quality, cost and supply requirements demanded by customers and end users especially automotive assemblers and suppliers, as well as competitive global markets, renders most rubber products manufacturers especially the SME manufacturers less competitive than those from Eastern Europe and other emerging Asian suppliers like China and India. There are existing problems, especially in the areas of new product development, productivity, quality, delivery, costs and financing. The lack of technical capability, reliance on bought in technology as well as limited volume for economies of scale are some of the factors that made the industry to be uncompetitive both internally as well as at international levels.

There is also a common problem of high level of “waste” and rejects and uncompetitive prices in rubber products manufacturing sector, and a need to reduce costs and to improve quality, productivity and efficiency. One of the successful steps taken by Malaysian Rubber Board to address this issue is through working hands on with factory personnel on site to improve quality and manufacturing processes.

Malaysian Rubber Board through her consultancy arm, RRIMCorp runs the A5 Program on Process and Quality Improvements to address the issues and making a competitive manufacturer and producer both locally and globally.

48

Overview of Waste Management in the Malaysian Rubber Industry

S. Anitha,*, V. Devaraj, M.N. Zairossani, Zaid Isa

Department of Technology and Engineering, Malaysian Rubber Board, P.O.Box 10150, 50908 Kuala Lumpur, Malaysia

*Corresponding author. Phone: +603-61561121, Fax: +603-61564418

Email: anitha@lgm.gov.my

Abstract

The natural rubber is a strategic crop and about a million of the smallholders are directly or indirectly dependent on this crop for their livelihood. In 2006 NR industry brought in a foreign exchange earnings of RM 25 billion. Despite its contribution to the Malaysian economy, it is still a major source of pollution with an estimate of 100 million liters effluent being discharged daily from rubber processing and about 30 million liters from manufacturing of rubber products. A closer look reveals that rubber industry consumes large volumes of water, uses chemicals and other utilities and discharges enormous amounts of wastes and effluent. With a new global trend towards a sustainable development, the industry needs to focus on implementing cleaner production technology, waste minimization, utilization of waste, resource recovery and recycling of water. The NR industry could attain sustainability by implementing an integrated approach by involving new and effective effluent treatment and waste utilization technology and value added products recovery to achieve zero-discharge status and minimize environmental impacts (eco–efficient). This approach would make NR Industry environmentally friendly and economically viable.

Keywords: natural rubber, waste minimization, cleaner production, recycling, zero-discharge, tilization.

49

Mechanical Properties of Poly(Ethylene Vinyl Acetate) Blended with Epoxidized Natural Rubber: Effect of Curing Agents

V. Tanrattanakul*, T. Kaewprakob

Polymer Science Program, Faculty of science, Prince of Songkla University

Hadyai, Songkla 90112 Thailand

(*corresponding author, e-mail: varaporn.t@psu.ac.th)

Abstract

Poly(ethylene vinyl acetate) copolymer (EVA) was blended with epoxidized natural rubber (ENR) by using an internal mixer. Rubber blends contained 10 and 30 wt% of ENR and were cured with various curing agents including sulfur, peroxide and phenolic resin, and the mixture of them. Tensile properties, tear strength, thermal ageing resistance and heat shrinkability were investigated. It is found that ENR decreased properties of EVA although morphology of the rubber blends showed compatibility of the blends.

Keyword: epoxidized natural rubber, rubber blends, mechanical properties, heat shrink.

50

Preliminary Results on Test of planting methods

Lim Khan Tiva1, Stephane Boulakia2

1 Cambodian Rubber Research Institute (CRRI)

#9, Penn Nuth Blvd.; P.O. Box: 1337, Phnom Penh, Cambodia

2 Centre de cooperation International en

Recherche Agronomique pour le Développement (CIRAD)

Abstract

In Cambodia planting material is an important concern for the rubber development. Climate has changed during the past decades and planting methods may need to evolve for a better adaptation. Fifty years ago rainfall was around 2300mm per year. More recently, rainfall was only about 1500mm per year in the traditional rubber cultivating area. Technical evolutions are also requested by the recent outbreak of a smallholders’ and private sector.

In two tests, CRII compares various planting and replacement methods, based on different combination of planting material types (cut-back, 1 whorl and 2 whorls polybag) and dates, in order to get the best initial establishment of the rubber plantation.

Preliminary results show that the planting materials with 1 whorl and 2 whorls polybag achieved high percentage of living plants and a much faster initial growth than cutback polybag. For early replacement, in the planting year, 1 whorl or 2 whorls polybags must also be favored; if carried out early, at the beginning of august, such a replaced trees will show imperceptible difference with the first planted with a reduced mortality rate compare to cut-back polybag. One year after planting, 1 whorl and 2 whorls polybags still present better growth and lower mortality.

Keyword: rubber, planting method, planting material, 1whorl polybag, cut back polybag, growth, mortality

51

First Five Years Results of Some Promising Clones from Large Scale Clone Trials in Cambodian Rubber Research Station

Phean Chetha 1, Hak Bunthuon 1, Chhek Chan1 and R. Lacote 2

1. Cambodian Rubber Research Institute (CRRI), 9, Penn Nuth Blvd., P.O. Box: 1337, Phnom Penh, Cambodia

2. CIRAD, Avenue Agropolis, TA80/B1/B2, 34398 Montpellier Cedex 5, France

Abstract

The first proposal of breeding research in Cambodian Rubber Research Institute (CRRI) is to test clones selected in foreign countries and to find out the best suitable plant material. Breeding program restarted recently in Cambodia. Large scales clone trials have been setting up in Cambodian Rubber Research Station and continue year by year. The study was on the growth, yield and diseases. Up to now we have nearly 10 LSCTs but only two LSCTs that reach five years of tapping. The first five years results from these 2 Large Scale Clone Trials confirm some other results such as the good vigour at opening of PB235, PB330, IRCA111, IRCA130, IRCA18, RRIM600, PB260 and PB280. Clones which good girth at fifth year of tapping are PB330, PB235, PB280, IRCA111 and PR303. By contrast, RRIM600, PB260, IRCA130, IRCA111 appear not more vigorous than GT1. The highest yielding clones in the first five years of tapping are IRCA130, PB235, PB330, IRCA111, RRIC101, PB260, PB280, IRCA18 and RRIM600. . Clone IRCA130, PB235, PB330, IRCA111, IRCA230, PB260 or PB280 could be considered as the most interesting among the clones tested in these two trials for the first five years of tapping. These preliminary results are still insufficient for evaluating these clones in those trials and are on going.

Keywords: Hevea brasiliensis, Cambodia, rubber clones, Large Scale Clone Trials (LSCT), growth, yield.

52

Effect of Temperature Constraints on Photosynthesis of Rubber (Hevea brasiliensis)

Boonthida Kositsup1, Poonpipope Kasemsap2, Philippe Thaler3 and Thierry Ameglio4

1 Tropical Agriculture Program, Kasetsart University, Bangkok 10900, Thailand

2 Department of Horticulture, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand

3 UPR Ecosystèmes de plantation, CIRAD, 34000 Montpellier, France

4 UMR-PIAF, INRA, Site de Crouelle, 63100 Clermont-Ferrand, France

Abstract

The temperature responses of photosynthesis of two rubber clones, RRIM600 and PB260 were determined over a wide range from 10 to 45 ˚C. Leaf photosynthesis measurements were performed at the Agriculture Faculty, Kasetsart University, Thailand and in a growth chamber at French National Institute for Agricultural Research (INRA-PIAF), Clermont-Ferrand, France. Photosynthetic rate of RRIM600 stayed almost constant between 23 to 37 ˚C, and decreased distinctly with increasing temperature from 38 to 45 ˚C. Photosynthetic rate of PB260 increased with increasing temperature from 10 ˚C, and also decreased distinctly by lowering the temperature below 24 ˚C or by increasing it above 36 ˚C. These results indicated the similar shape of temperature response of photosynthesis of two rubber clones.

Key words: Rubber, Hevea, photosynthesis, temperature response

53

Coupling Effects of Water and Fertilizers on Latex Yield of Hevea brasiliensis*

Hua Yuangang, Chen Qiubo, Lin Zhaomu and Luo Wei

(Rubber Research Institute/Ministry of Agriculture Key Laboratory for

Tropical Crops Physiology, CATAS, Danzhou, Hainan, China 571737)

Abstract

Nutrients and water are two limiting factors on rubber growth and latex yield. The effects of irrigation and fertilizer supply to rubber trees have been an interesting field for agronomists, physiologists and ecologists. In the present experiment, a China-bred Hevea Clone SCATC 7-33-97 with 17 years old were used as plant materials. The comprehensive coupling effects of application rate of N, P and K fertilizers, and irrigated water on rubber yield and dry rubber content were studied by the general orthogonal rotation design of quadratic regression with four factors and five levels under field conditions. A regression model was established on the basis of quadratic regression analysis of rubber yield and related factors and their treatment levels. Results showed that the coupling effect of water and fertilizer on rubber yield and dry rubber content are noticeable. The impacts of various factors on rubber yield are in a decreasing order: N dosage>water quantity>P dosage>K dosage. The coupling effects between factors are N and water >N and P> P and water> K and water. A negative interaction effect was observed between K dosage and water. The optimal combination of the four factors for water and fertilizers coupling effects was worked out as urea at 476.39 kg/ha, calcium superphosphate at 187.70kg/ha, potassium chloride at 225.77 kg/ha, and soil moisture content at 88.71%.

Keywords: Hevea brasiliensis; Coupling effect ; Water and fertilizer; Latex yield; DRC

54

The Agronomic Performances of Hevea Brasiliensis

Clone IRCA111 in South-West of Côte d’Ivoire

S. Obouayeba1, O. Gabla2, R. Lacote3, K. B. E. Dibi1, A. Doumbia2, E. Soumahin1,

and K. Dian2

1: CNRA, 01 BP 1536 Abidjan 01, Côte d’Ivoire

2: Hevego, Rubber Research Station BP 793, San Pedro, Côte d’Ivoire

3: Cirad, UR 34, Tree Crop Based Systems, TA B/34, 34398 Montpellier, France

Corresponding author: S. Obouayeba, obouayebasam@yahoo.fr

Abstract

The clone IRCA 111 of Hevea brasiliensis, produced in 1975, in Côte d’Ivoire, is one of the clones of the IRCA sets to promote in the rubber-producing context. To this effect, the investigating, in the commercial plantations conditions are indispensable to define the optimal conditions of its exploitation in view of its popularization. For that to make, a survey of the agronomic behavior of the clone IRCA 111 is carried out since about ten years to the south-west of Côte d’Ivoire. This survey aims to determine the best of tapping systems allowing the IRCA 111 to express its agronomic performances better. The assessment of these performances is achieved by the application of 6 tapping systems. The optimal exploitation of the IRCA 111’s potentialities is given by the tapping system (d/3 6d/7 ET 2.5 % 4/Y), tapping 2 times per week with 4 annual stimulations. For a possible shortage and/or dearness of tappers, the tapping weekly, stimulated 10 times per year, is the most suitable. The production of rubber per tree and per tapping (g/t/t) is in logarithmic relation with the intensity of tapping. The rate of tapping panel dryness (TPD) is bound also to the intensity of tapping by a polynomial relation of quadratic type. This survey shows that the IRCA 111 is altogether, a high producer, fast growth and fast or active metabolism clone.

Keywords: Hevea brasiliensis, clone IRCA111, Côte d’Ivoire, popularization, agronomic performances, tapping system, optimal exploitation, high producer, active metabolism.

55

Maturation of Natural Rubber Cup Coagula:

Characterization of Industrial Conditions

J.Intapun1, V.Tanrattanakul2, E.Dubreucq3, F.Bonfils4, J.Sainte-Beuve4, L.Vaysse5-6

1 Faculty of Technology and Management, Prince of Songkla University, Surat Thani 84000, Thailand

2 Polymer Science Program, Faculty of Science, Prince of Songkla University, Hadyai 90110, Thailand

3 Montpellier SupAgro, UMR SPO, Montpellier 34000, France

4 Cirad, UMR Agropolymer Engineering and Emerging Technologies (IATE), Montpellier 34000, France

5 Cirad, UMR IATE, DORAS Center, Kasetsart University, Bangkok 10900, Thailand

6 Corresponding author: laurent.vaysse@cirad.fr

Abstract

In factory practice, cup coagula are stored in pile for a variable period of time before being processed as Technically Specified Rubber (TSR). During this so-called “maturation” period, neither the microbiological phenomena occurring, nor their implications on properties of raw natural rubber are known. Before conducting experiments in controlled conditions (laboratory), the present work focused on the characterization of real maturation conditions (factory) in a pile of coagula. Physico-chemical conditions [temperature, relative humidity (RH) and oxygen content] and rubber properties [total solid content (TSC), pH, initial plasticity (P0) and plasticity retention index (PRI)] were analyzed at different depths from the top of the piles. It was found that temperature and relative humidity of the air within the piles increased with the depth (34°C and 55% RH at the top, more than 40°C and 80% RH at 1 m deep). In contrast, oxygen content decreased as the depth increased (21% at top and less than 5% at 1m deep). Rubber properties were found to depend not only on the maturation time but also on the position within the pile. During maturation, an increase was observed for the mean value of several parameters: TSC (from 78 to 82), pH (from 6 to 6.5), P0 (from 35 to 45) and PRI (from 30 to 45). An influence of the location of cup coagula within the piles was also observed. At the end of the maturation period, the pH of cup coagula decreased significantly with the depth of the pile (from 7.2 at top to 6.3 at 2 m deep). An inverse pattern was observed for P0 (from 28 at top to 45 at 2 m deep). TSC was found to be minimal at the heart of the pile. The results suggest that microbial activities may play an important role in the evolution of some physico-chemical properties of cup coagula and of their environment within storage piles during maturation.

Keywords: Hevea brasiliensis; natural rubber; cup coagula; maturation; plasticity retention index (PRI)

56

Development of Rubber Plantations in Nigeria

M. U. B. Mokwunye and K. O. Omokhafe

Rubber Research Institute of Nigeria

Iyanomo, Benin City.

(E-mail: rubberresearchnig@yahoo.com)

Abstract

The development of rubber plantations in Nigeria was evaluated to highlight the trends of plantation establishment and efforts for sustainability. Following the introduction of Hevea brasiliensis into Nigeria in 1895 and the obvious advantage of Hevea over an indigenous rubber tree, the Funtumia, Hevea rubber plantations expanded to 247,000ha in 2000 but declined to 154,000 in 2006. The Presidential Initiative on Rubber (PIR) is the intervention of Federal Government of Nigeria directed towards a reversal of the decline in natural rubber production in Nigeria. The strategies for the development of rubber plantations under the PIR are expected to produce 360,000ha new plantations from 2007 to 2018. The PIR is a multi-sectoral programme of Government, Private Sector (including Rubber Estates and Banks) and regulatory agencies. The PIR is investor-friendly with prospects for both local and foreign investors.

57

Effect of Three Rootstocks on the Same Scion PR107 of Hevea brasiliensis

Cao Jianhua, Lin Weifu, Wu Jilin, Chen Junming

(Rubber Research Institute/Key Laboratory of Ministry of Agriculture for Tropical Crops Physiology, CATAS, Danzhou, Hainan. P. C. 571737)

Abstract

The content of IAA and iPA in latex of three kinds grafted Hevea brasiliensis trees, bred by tissue culture with anther cells, named self-root clones, and consisted of the ReYan88-13, Haiken2 and Dafeng99 as the rootstocks respectively, PR107 as the scions, were determined by using plant hormonal immunoassay(PHIA). Meanwhile, the dry rubber content (DRC) and yields were also determined by using Micro wavelength instrument for detecting latex, DH925A. And then their interacting relationships were analyzed. The results indicated that the different rootstock materials had an apparent effect on the same scion in content of IAA and iPA of latex, DRC and yields. However, the effects were different because of the different grafting materials and patterns. It indicated that the effect of different rootstocks, Reyan88-13, Haiken2 and Dafeng99 on the same scion PR107 were different. In the same grafting pattern, the contents of IAA and iPA of latex, DRC, and yield were found to have apparent differences in different seasons. This indicated that seasonal factors had a significant effect on IAA and iPA in latex, DRC and yields. The tapping frequency had an apparent effect on contents of IAA and iPA in latex, DRC and yields, but there were differences in the effects because of grafting patterns and materials. With the increase in tapping frequency, the content of IAA, iPA, and yields increased apparently, but DRC decreased. There was an apparently positive relativity between IAA and iPA in latex, DRC and content of IAA or the ratio of IAA/iPA. The relativity between DRC and content of iPA was not apparent, but close to significance level statistically. However, there were no apparent relativities between yield and content of IAA, iPA, or the ratio of IAA/iPA.

Keywords: Hevea brasiliensis, rootstock, scion, effect

58

A Mini Juvenile Bud Stick and Mini Seedling Budding of Hevea brasiliensis

Chen Xiongting, Peng Ming, Zhang Xiujuan, Wang Ying, Zheng Xueqin

Institute of Tropical Bioscience and Biotechnology ,CATAS, No.4 Xueyuan Road, Longhua District, Haikou, Hainan 571101, China

Abstract

A mini juvenile bud stick was cultured in vitro and the bud patches from this bud stick when it was about 0.2cm in diameter were used for mini seedling budding. Mini seedling budding is easy and simple in operation without removing the xylem of the budpatch, and the budding survival rate was high. The mini juvenile bud stick is best for mini seedling budding.



Keywords: Hevea brasiliensis, mini bud stick, mini seedling budding

59

Effect of DCD and HQ on the Transformation of Urea in Latosol Soil under Rubber Plantation

Luo Xuehua

Rubber Research Institute, CATAS, Danzhou, Hainan, 571737, China

Abstract

Using urea as nitrogen source and aerial incubation method, this paper dealt with the transformation of Urea and the nitrification potential of latosol soils under Rubber Plantation in tropical region and evaluated the effectiveness of Urease inhibitor and nitrification inhibitor, hydroquinone (HQ) and dicyandiamide (DCD), in inhibiting urease and nitrification.

The urease activities of latosol soils of the rubber plantation were strong, and no matter whether the Urease inhibitor and nitrification inhibitor were applied to the rubber plantation soils, the urea was hydrolyzed completely within 4 days, and hydrolyzed completely within 1 day especially for the soil (c) mixed cultivation with the green manure and fertilizer.

Nitrification potential of soil (c) was much higher than that of soil (a) between rows of rubber tree, the area was not fertilized. The transformed NH4+N in the soil (c) began to nitrify strongly after incubation 4 days, and almost nitrified completely with the nitrification rate of 92.4% in 14d, and the value of soil (a) was 1.5% in 14d, and its maximal nitrification ratio was only 46.2 %. However the nitrification rate of Da was below 5.2% during the whole incubation 63d; and that of Dc was below 12% before 49d.

On condition that the ratio of urea to the soil, DCD to the urea and HQ to the urea was 0.025%, 5%, 0.4% respectively, the hydrolysis of urea was not inhibited evidently. However, the nitrification rate was slowed considerably by addition of HQ and DCD to soil (c) with 49 days and to soil (a) with more than 60 days.

Key words: DCD, HQ, Transformation of Urea, Latosol soil, Rubber plantation

60

Components of Inorganic Phosphates in Rhizosphere of Rubber Tree (Hevea brasiliensis)

wang Wenbin1,3, Geng Jianmei2, Wu Xiaoping1,3 , Huang Xiusong2, Luo Xuehua1,3

Rubber Research Institute, Chinese Academy of Tropical Agriculture Sciences, Danzhou,Hainan, China 571737. 2 College of Agronomy, Hainan University, Danzhou, Hainan, China 571737. 3 Ministry of Agriculture Key Laboratory for Tropical Crops Physiology

Abstract

Field experiment was carried out to study the inorganic phosphate components in rhizosphere of rubber tree. The results showed that treatments of various amount of fertilizer had little effects on the contents of inorganic phosphates of rhizosphere and bull soil in a short time. Both in 0~20cm and 20~40cm layer, the contents of Al-P and Fe-P are higher in the rhizosphere han in the bull soil, Al-P is significantly (p<0.05) higher than that in bull soil as well as the total content of inorganic phosphates, for Fe-P only the difference in 20~40cm layer is significant. The content of O-P in the rhizosphere soil is also higher than that in bull soil (p<0.05, one-tailed test), while the content of Ca-P in the rhizosphere soil is not significantly different from that in bull soil. The contents of Al-P and Fe-P in rhizosphere soil and bull soil in the 0~20cm layer are both significantly (p<0.05) higher than that in the 20~40cm layer. In 20~40cm layer the content of O-P is higher, but the difference isn’t significant, and the difference of Ca-P is also not significant. The total contents of inorganic phosphates of rhizosphere and non- rhizospherel are both higher in 0~20cm layer though the difference between two soil layers isn’t significant.

Key words: rubber tree (Hevea brasiliensis); rhizosphere soil; inorganic phosphate component

61

Revaluing of terminal bud Pruning on Young Rubber Trees

Xie Guishui12 Huang Yuanfang1

1 college of Resources and Environment, China Agricultural University, Beijing 100094, China

2 Rubber Research Institute, CATAS, Danzhou, Hainan 571737, China

Abstract

Nowadays, the measure of terminal bud pruning on young rubber tree has been become a routine method. The approach of pruning is to cut the terminal bud or whorl leaf on the top. After the bud sprouting, 3 buds were maintained to form the backbone branches. The main original purpose of this measure was as follows: (1) to reduce the height of the rubber tree and enhance the ability of resisting wind; (2) to form the crown of rubber tree as soon as possible and promote the stem growth. However, the practice showed that both these purposes could not be achieved easily, or that the result of the method was not remarkable.

On the other hand, the disadvantages of this method are obvious. For example, the timber accumulation will be reduced, and the useable area of tapping on the stem will also be lessened. Meanwhile, the irrational branch structure due to incorrect operation will add to the wind damage to the rubber tree. Furthermore, repeated top-pruning of the young rubber will accelerate aging of the tree. It is concluded that the measure of terminal bud pruning of young rubber tree is not suitable.

Key words: rubber tree; young tree; terminal bud pruning

62

Lipid composition of Hevea brasiliensis latex and dry rubber: characterization and relation with some physical properties

S. Liengprayoon 1-2-4, E. Dubreucq 2, K. Sriroth 1 , F. Bonfils 3, L. Vaysse 4-5

1 Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, Bangkok 10900, Thailand

2 Montpellier SupAgro, Montpellier 34060, France

3 Cirad, UMR Agropolymer Engineering and Emerging Technologies (IATE), Montpellier 34000, France

4 Cirad, UMR IATE, DORAS Center, Kasetsart University, Bangkok 10900, Thailand

5 Corresponding author: laurent.vaysse@cirad.fr

Abstract

The purpose of this work was to characterize the lipid composition of natural rubber latex and unsmoked sheets from Hevea brasiliensis clones, namely RRIM600, GT1, PB235 and BPM24 and to study correlations between this composition and some properties of raw rubber such as Initial plasticity, Plasticity Retention Index and Breakdown Index. 15 samplings have been performed over a 3 years period. Lipid contents were found to be clonal dependent. They were in the range of 2.5% to 3.7% vs dry rubber for fresh latex and 2% to 3.3% for sheet rubber. Lipids were separated by families i.e. phospholipid, glycolipid and neutral lipid and each family was characterized. In sheet rubber the proportion of each family was found to be 80%, 15%, and 5% respectively. Polar lipids were much less present in sheet rubber than in latex, which suggested an effect of the sheet production process on lipid composition. The major fatty acid detected in lipid extracts was linoleic fatty acid except for PB235 clone which contains a rare fatty acid in important quantity, namely furanoid fatty acid. The unsaponifiable fraction of lipid extract, analyzed by GC-MS, was constituted by fatty alcohols (9%), g-tocotrienol (12%), a-tocotrienol (5%), stigmasterol (7%), b-sitosterol (50%), and D5-avenasterol (17%). The unsaponifiable composition of rubber sheet was not different from that of latex. Concerning glycolipids, which have been identified by HPLC-MS, four main glycolipids, namely monogalactosyl diglycerides (MGDG), digalactosyl diglycerides (DGDG), esterified steryl glucosides (ESG) and sterylglucosides (SG) were detected in the respective relative proportions of 7%, 47%, 13%, and 33%. Phospholipids consisted of phosphatidylinositol (PI), phosphatidyl ethanolamine (PE), phosphatidic acid (PA), lysophosphatidylinositol (LPI), phosphatidylcholine (PC), and lysophosphatidylcholine (LPC) in the respective proportions of 3%, 4%, 9%, 2%, 57% and 25%. The analyses of physical properties of rubber such as Initial plasticity, PRI, Mooney viscosity and breakdown index permitted to distinguish clear differences between clones. A few correlations between some lipids characteristics and physical properties of rubber are discussed.

Keywords: natural rubber; Hevea brasiliensis; lipid; non-isoprene; physical properties

63

Importance of the Homogenization Method for Natural Rubber Characterization by Variable Speed Mooney Viscometer

C. Kim1, F. Bonfils2*, J. Sainte-Beuve2, M-H. Morel3, S. Guilbert3

1. Cambodian Rubber Research Institute, P.O. Box 1337, Phnom Penh, Cambodia.

2. UMR1208 Ingénierie des Agropolymères et Technologies Emergentes, Cirad, TA B 62/16,

73 Rue Jean François Breton, 34398 Montpellier Cedex 5, France.

3. UMR1208 Ingénierie des Agropolymères et Technologies Emergentes, SupAgro, 2 place

Pierre Viala, 34060 Montpellier, France.

* Corresponding author: frederic.bonfils@cirad.fr

Abstract

The Mooney viscometer is an industrial tool that is widely used to characterize elastomers. Cantaloube and Cocard [1] recently showed that the classical rotor speed, 2 rpm, leads to misleading information on natural rubber (NR) due to structural failure during the test by shearing at high speed. It was recommended to using rotor speeds under 0.2 rpm for NR characterization. Our main objective was to evaluate the influence of the two main homogenization methods used (ISO and SMR) on Mooney viscosity determined at different speeds (0.02 - 4 rpm). The study was done on model samples of raw NR which structure was characterized by SEC-MALLS. The results showed that though the differences in Mooney viscosity between the two methods of homogenization were small at 2 rpm, they could be very large at low speeds (< 0.2 rpm). The main reason would be the difference in structures of NR homogenized by different methods, differences in temperature and number of passes.

Keywords: Natural rubber, homogenization, Mooney viscometer, variable speed Mooney viscosity

64

Components Analysis of Different Solvents Extracts from Rhizosphere soil of Rubber Tree by GCMS

YinYulian1, 2 Wang Wenbin1, 3, Wu Xiaoping1, 3, Luo Xuehua1, 3, Wu Jianwen1, 2

1. Rubber Research Institute, CATAS, Danzhou, Hainan 571737, China. 2. College of Agronomy, Hainan University, Danzhou, Hainan 571737, China. 3. Ministry of Agriculture Key Laboratory for Tropical Crops Physiology, Danzhou, Hainan 571737, China

Abstract

Chemical compounds extracted from rhizosphere soil of rubber tree were analysed by gas chromatography–mass spectrometry (GC-MS). There were 33, 36 and 34 constituents identified respectively from the aether, hexane and ethyl acetate extracts, accounting for 84.78%, 93.88% and 86.37% of the total peak areas, respectively. GC-MS analysis method for different extracts of rhizosphere soil of rubber tree was established. Detected compound sorts in the three extracts were mainly ester, hydrocarbon, ethanol and acid as well as hydroxybenzene, aldehyde, etc. But the composition and contents of the different solvents extracts were different, and butyl hydroxyl toluene, 1,3-propanediol, 2-ethyl-2-(hydroxyl methyl) and 9-Octadecenamide were the major components in the three extracts and their contents were 23.55%, 17.06% and 12.78% of the total peak areas, respectively.

Keywords: rhizosphere soil of rubber tree, chemical compound, GC-MS

65

Chemical Control of Chinese Taxillus on Rubber TreesChemical Control of Chinese Taxillus on Rubber TreesChemical Control of Chinese Taxillus on Rubber Trees*

Zhi-Wei Fan, Xing-Guo Dong, Yu-Fang Zhou and Yi-De Shen

Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Danzhou, Hainan 571737, P R China

Abstract

Chinese Taxillus belonging to the family Loranthaceae is commonly found as a parasite on mature rubber trees in Hainan, China. Injecting a chemical compound Miesangling into the rubber trees indirectly kills the Chinese Taxillus. This method is simple and give 80 per cent or more control of Chinese Taxillus, and yet it is safe to the rubber trees hosts.

Keywords: Chinese Taxillus; Loranthaceae; Miesangling; rubber tree

66

Pythium Vexans Causing Patch Canker of Rubber Trees on Hainan Island, China

H. C. Zeng1, H. H. Ho2 & F. C. Zheng3

1State Key Laboratory of Tropical Crop Biotechnology, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Chengxi, Haikou, Hainan 571101, China; 2Department of Biology, State University of New York, New Paltz, New York, 12561, USA; 3Environmental and Plant Protection Research Institute, Chinese Academy of Tropical Agricultural Sciences Baodao Xincun, Hainan 571737, China

Abstract

This is the first report of patch canker disease of rubber trees (clone RRIM600) in China. It is characterized by discrete irregular patches of rotted, discolored bark and wood, accompanied by a decrease in latex flow. A total of seven isolates of Pythium vexans were obtained from the diseased bark of the trunks and roots of rubber trees. Inoculating these isolates into healthy, mature rubber trees resulted in symptoms similar to patch canker and the same fungal species was re-isolated from the diseased tissues. This is also the first record of Py. vexans in Hainan.

Key words: bark canker, Hevea brasiliensis, oomycete, tree disease

67

Rapid Molecular Identification and Detection of Corynespora cassiicola of Hevea brasiliensis

Xianbao Liu Jimiao Cai Xianxin Pan Honghua Gao Jianhua Peng Guixiu Huang*

Key Laboratory for Baleful Biology Detection and Monitoring of Tropical Agriculture of Hainan.Province, Environment and Plant Protection Institute, CATAS, Danzhou, Hainan, 571737, China

Abstract

Corynespora leaf fall disease (CLFD) of Hevea brasiliensis is caused by the fungus Corynespora cassiicola. This disease has emerged as a major constraint for natural rubber production over the last two decades. Eighteen strains of C. cassiicola from China were used in this study. Genomic DNAs were extracted and the ribosomal DNA internal transcribed spacer (ITS) regions were amplified and sequenced. The results showed only small variances in base sequences. Species-specific PCR primers CorP1 and CorP2 for C. cassiicola were designed after multiple sequence alignment of C. cassiicola against other species from the Corynespora genus. A single fragment approximately 300 bp in length was amplified from DNA from isolates of C. cassiicola. No product was amplified with DNA from the other 18 fungi or from DNA of rubber tree leaf tissue. The detection limit for C. cassiicola genomic DNA was 0.1 pg using species-specific primers.

Keywords: Hevea brasiliensis, Corynespora cassiicola, internal transcribed spacer (ITS), species specific primer, PCR assay

68

Phylogenetic Relationships and rDNA-ITS Sequence Analyses of Oidium heveae, a Powdery Mildew of Rubber Tree

Xianbao Liu1, Honghua Gao1, Jimiao Cai1, Xianxin Pan1, Keli Zhang1, Guixiu Huang1*

1. Key Laboratory for Baleful Biology Detection and Monitoring of Tropical Agriculture of Hainan Province, Environment and Plant Protection Institute, CATAS, Danzhou, Hainan, 571737, China

Abstract

Powdery mildew of rubber tree caused by Oidium heveae Steinm is an important disease of rubber plantations worldwide. We collected 20 samples of rubber powdery mildew from Hainan, Guangdong, Guangxi and Yunnan provinces in China, and extracted their genomic DNAs. The ribosomal DNA internal transcribed spacer (ITS) regions were amplified and sequenced. Nucleotide sequence analysis results showed that O. heveae strains infecting Hevea brasiliensis were divided into two groups.

Key word: Hevea brasiliensis, Oidium heveae Steinm, internal transcribed spacer (ITS), PCR

69

Identification of Resistance of Hevea brasiliensis Clones to Corynespora Leaf Fall Disease

Xin Lu Jianhua Peng Keli Zhang Guixiu Huang*

Key Laboratory for Baleful Biology Detection and Monitoring of Tropical Agriculture of Hainan Province; Environment and Plant Protection Institute, CATAS, Danzhou, Hainan, 571737, China

Abstract

Corynespora leaf fall disease (CLFD) of Hevea brasiliensis caused by the fungus Corynespora cassiicola has emerged as a major constraint for natural rubber production. This study evaluated disease resistance among 45 Hevea germplasms collected from the National Rubber Tree Nursery by inoculating pathogenic strains, leaf-puncture bioassays, and leaf-wilt bioassays utilizing crude toxin. The results showed that different Hevea clones differed in their resistance to CLFD. Among 45 experimental varieties, there were 13.317.8% disease-resistant varieties, 66.773.4% slightly disease-susceptible varieties, and 11.117.8% disease-susceptible varieties.

Keywords: Hevea brasiliensis, Corynespora leaf fall disease, crude toxin, resistance identification

70

Rubber Flux: Co2, Water and Energy Budget of Rubber Plantations in Thailand

Philippe Thaler1, Pongpan Siripornpakdeekul2, Poonpipope Kasemsap2, Olivier Roupsard1, Arak Chantuma3, Sornprach Thanisawanyangkura3, Kumut Sangkhasila2, Jean-Marc Bonnefond5

1 UPR Ecosystèmes de plantation,Cirad 34000 Montpellier France

2 Faculty of Agriculture, Kasetsart University, Bangkok, Thailand

3 Faculty of Science, Kasetsart University, Bangkok, Thailand

4 Chachoengsao Rubber Research Center, RRIT-DOA, Sanam Chai Ket, Thailand

5UR EPHYSE, INRA, Bordeaux, France

Abstract

Rubber Flux aims at providing a complete picture of CO2, water and energy budget of a rubber plantation in Eastern Thailand.

Beyond the evaluation of the fluxes, our purpose is to partition them among the different components of the plantation ecosystem (canopy, trunks, roots, under storey, soil) and the different functions (photosynthesis, respiration, evapotranspiration ) in order to understand the factors controlling the carbon, water and energy budgets of the ecosystem.

The experiment is situated at the Chachoengsao Rubber Research Station located in Phanom Sarakham district, about 140 km east of Bangkok. The observation site is located in a 6 ha plot at the center of the 350 ha station. The plot itself is planted with a monoclonal stand (clone RRIM 600). Trees were 13 years old in 2007. The average height was 20 m and average girth at 1.7 m was 60 cm. Initial planting density was 500 trees/ha and actual stand density was 454 trees/ha in June 2006. Trees are tapped for latex production for 5 years.

Carbon fluxes of rubber plantation ecosystem are continuously measured by the eddy covariance method (ED). Evapo-transpiration (ET) is measured by ED and water balance together. Meanwhile, amounts of carbon (C) stored in the trees will be evaluated by measuring biomass increment of the plantation, in combination with estimations of the carbon content at the different compartments. ED methodology was adapted from a similar experiment developed by our research group on another tropical tree crop plantation, coconut tree, in Vanuatu islands. The flux tower is 25 m high. Three-demensional (3-D) sonic anemometer Young 81000V 20 Hz is used together with an open path gas analyser (LI-7500; LI-COR, Inc., Lincoln, Nebraska, USA). Raw data are collected and pre-processed by the “Tourbillon software (INRA-Bioclimatologie, Bordeaux, France) for a time-integration period of 300 s. Raw data are post-processed using EdiRe software (University of Edinburgh, UK) into half-hourly values. All data are despiked according to variance filters, planar fit is applied (parameters are calculated monthly), and vapour is corrected for buoyancy. Weather station measures semi-hourly net radiation (Rn), photosynthetically active radiation (PAR), diffuse PAR (PARdiff), reflected PAR (PARreflected), global radiation (Rg), Air temperature (Ta), Relative humidity (Rh), wind speed, wind direction, rainfall, vertical profile of air temperature (TCs). Energy balance will be assessed by measurements of net radiation (Rn) and estimation of the energy partitioning among heat fluxes and heat storage. Results obtained at the ecosystem scale by these methods will be compared to gas exchanges measured at the level of the different compartments (canopy, trunk, root system, soil, etc). Thereby, the validated CO2 and H2O fluxes will be used to model gas exchanges of rubber plantation ecosystem according to climate and other environmental parameters as well as crop management.

71

Sap Flow and Water Status in Adult Rubber Trees

Sumit Kunjet1, Philippe Thaler2, Olivier Roupsard2, Arak Chantuma3, Pongpan Siripornpakdeekul1, Poonpipope Kasemsap1, Kumut Sangkhasila1

1 Faculty of Agriculture, Kasetsart University, 10900 Bangkok, Thailand

2 UPR Plantation Ecosystems, Cirad, Montpellier, France

3 Chachoengsao Rubber Research Center, RRIT-DOA, Sanam Chai Ket, Thailand

Abstract

Interactions of large scale plantations with variable environment is a major issue. This research studies the water relations in soil and plant in 13 years old rubber plantation, under natural condition of Chachoengsao Ruber Research Center (CRRC). In order to assess water balance of tree plantation on plot scale, it is necessary to partition total water flux measured by eddy-covariance. Therefore, accurate dynamic measurement of tree transpiration is required. Sapflow was measured by heat dissipation method (Granier, 1987) using 20 mm-long radial probes, connected to a data logger. The calibration of the probes was checked in laboratory with reference to the gravimetric method. We adjusted the experiment devices to rubber field conditions and evaluated the different sources of variability to design the appropriate monitoring process. The sapflow density decreased in the defoliation period and increased along the refoliation period during dry season, after that it was almost constant during vegetative growth period except during high rain events. Stand transpiration was quite similar to sapflow density. On a tree scale, seasonal and daily time of leaf water potential across the canopy and stomatal conductance were monitored together with climate data and soil moisture content. The soil moisture content was measured by gravimetric method and tensiometer. Plant water potential was measured with pressure chamber and stomatal conductance was detected by LI-6400. A positive relationship was found between soil metric potential and daily stomatal conductance. However, daytime leaf water potential was unaffected by soil water content. In addition, leaf water potential depended on measurement height and daily stomatal conductance related to leaf water potential, sapflow density, and height.

72

Results of the two Clone Trials: Promising Rubber Clones

for Commercial Planting

Hla Myint1, Aye Pe2, Khin Myo Swe2

1Myanmar Rubber Planters and Producers Association, No.127, 40th St., Kyauktada T/S, Yangon, Myanmar. Email: hmyint@mptmail.net.mm

2Applied Research Centre for Perennial Crops, Phaauk, Mawlamyine, Mon State, Myanmar. Email : arcpc@baganmail.net.mm

Abstract

Two clone trials were set up, each with ten clones and the clones were studied for their growth vigour and the yield. Since the trials were conducted at the area with high annual rainfall of over 4,500 mm and where Phytophthora leaf disease was endemic and very severe, their resistance to the disease was also studied.

First Series Clone Trial was planted at two places, Mudon and Thanbyuzayat in 1986 and 1987 respectively. The study revealed the two clones PB 260 and PB 235 to be possessing of satisfactory growth vigour and yield, and above average resistance to Phytophthora leaf disease. On the contrary, RRIM 600 was found to be the poorest in growth as well as in the yield. It was the least resistant clone to Phytophthora.

Second Series Clone Trial was planted at Mudon in 1990. Out of the ten clones studied, BPM 24 was found to be outstanding in the yield performance and also highly resistant to Phytophthora leaf disease. Its growth vigour during immaturity and after tapping was average to above average levels respectively. RRIC 100 was found to have vigorous growth during immaturity and average growth vigour after tapping. It was above average in resistance to Phytophthora. Its yield level was moderate. RRIM 717 was found to possess good growth vigour with moderate yield level. Its resistance to Phytophthora leaf disease was above average.

Keywords: Clone trial, cultivar, growth vigour, yield, Phytophthora leaf fall, resistance.

73

Hevea Clonal Resistance to Wind Damage

Mokwunye,M.U.B., Omokhafe, K.O., *Omorusi, V.I., Ogbebor, N.O.; Evueh, G.A., Orimoloye, J.R.; Owie, O.E.D., S. Ehika.

Rubber Research Institute of Nigeria, P.M.B. 1049, Benin City, Nigeria

Abstract

A field survey was conducted to determine the effect of wind damage on Hevea clones in a 40-hectre polyclonal garden at the Rubber Research Institute of Nigeria main Station, Iyanomo, Benin City, Nigeria. Nine Hevea clones were evaluated for resistance against wind damage, and these comprised six local (NIG. 800, 801, 802, 803, 804, 805) and three exotic (PR 107, GT1 and RRIM 707) clones parameters of the clones assessed were branch/trunk snapping, canopy load damage and root lodging. A total of 463 trees planted in a sub plot were sampled for each clone replicated thrice in three blocks investigated. Wind velocity was evaluated for three months-part of the rain stormy period from August to October, 2006. Results showed that mean percentage Hevea resistance to wind damage varied among the clones with the least and highest damage records ranging from 2.23 to 8.05% in RRIM 707 and NIG. 804, respectively, with intermediates scores. These low values obtained indicated that the clones were generally tolerant to wind damage effect. However, the least level of resistance recorded in NIG 804 was significantly different from other clones (LSD=5.83-410>3.85) except for NIG. 805 (LSD= 3.02<3.85) and NIG.802 (LSD=2.94<3.85). Average wind velocity recorded was generally low (1.7m per sec.) to produce any significant wind damage effect on the branch and trunk. Effect of wind damage on canopy load was significant (P<0.05). NIG. 804 was the most affected (87.83%) while the least effect in NIG 800 (16.42%). The high percentage value in NIG. 804 was significantly different from values obtained for other clones (LSD=39.77<71.41 – 46.15) except for NIG.802 (LSD=39.77>377.43). The susceptibility of canopy to wind damage was observed to be attributed to the heavy canopy load bearings. No appreciable incidence of root lodging could be obtained. Latex (biomass) yield in the period was high with a total output of 78,863.16kg. The present study reports Hevea clonal resistance to wind damage as well as provides suggestions in reducing incidence of canopy load damage in rubber plantations.

Keywords: Hevea clones, wind damage, branch/trunk, canopy load, clonal garden.

74

Advances on biodiversity of natural rubber biosynthesis and regulations on natural rubber biosynthesis

W B. Liao1, P J Zhao1, M Peng 1

1. State Key Laboratory of Tropical Crop Biotechnology, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan 571101, China

Abstract

Although more than 2 500 plant species are known to produce cis-1,4-polyisoprene, H. brasiliensis, which grows only in subtropical climates, is currently the only commercial source of NR. With the molecular biotechnology on rubber tree and cloning of many key gene involved in rubber biosynthesis development, using the methods of molecular biotechnology to improve the production of NR and seek ing the replacement of NR from other plants and microorganisms are becoming the hotspot of NR research areas. In this paper, Advances on biodiversity of natural rubber biosynthesis and regulations on natural rubber biosynthesis are reviewed.

Keyword: Hevea Brasiliensis, Natural rubber biosynthesis, Regulations on natural rubber biosynthesis.

75

Relationship between Rate of Laticifer Differentiation, Number of Laticifer Rows and Rubber Yield Among 1981 IRRDB Germplasm Collections of Hevea brasiliensis

W.-M. Tian1, X. Zeng1, M.-J. Shi1, Y.-Y. Chen1, H.-S. Huang1

1. Key Laboratory for Tropical Crops Cultivation and Physiology, Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences, Danzhou, Hainan 571737, P.R.China

Abstract

Early selection based on parameters related to yield is important in Hevea breeding programmes. In an attempt to characterize such parameters, we investigated the variation in TNLD (time needed for laticifer differentiation) of the 1981 IRRDB germplasm accessions by means of an experimental system for the induction of secondary laticifer differentiation in relation to RLCL (ratio of laticifer rows to the cell layers of the functional phloem) and rubber yield of the corresponding adult plants. The results demonstrated that TNLD varied among the examined 63 germplasm collections and was correlated to RLCL (r=0.5795, highly significant) and rubber yield (r=0.4558, significant level) of the corresponding adult plants. TNLD, together with the numer of the induced laticifer cells, is expected to be a candidate parameter related to rubber yield.

Keywords: conventional breeding, early selection, Hevea brasiliensis Muell. Arg., laticifer differentiation, mechanical wounding, 1981IRRDB rubber tree germplasm collections.

76

The Current Status of Three Common Leaf Disease of Para Rubber in Nigeria: Preliminary Investigations

*Ogbebor, O. N.; Omorusi, V. I. and Evueh, G. A.

Plant Protection Division, Rubber Research Institute of Nigeria, PBM. 1049, Benin City. *Corresponding Author: ogbeb06@yahoo.com

Abstract

Three commonly occurring leaf diseases of Hevea brasiliensis Muell. Arg. (Bird’s eye spot, Colletotrichum leaf fall and Corynespora leaf fall) in nine Hevea clones comprising six local clones (NIG 800, 801, 802, 803, 804, and 805) and three exotic clones (PR107, RRIM 707 and GT1) were evaluated for foliar disease severity. Incidence of Bird’s eye spot disease was highest with scores ranging from 27.44%– 54.17%, while the least result were recorded in Corynespora leaf fall (2.59% - 10%). NIG 804 had the highest disease indexes in Bird’s eye spot and Corynespora leaf fall while NIG 801 recorded the highest in Colletotrichum leaf fall. This study suggests adequate control of the leaf diseases to forestall an epiphytotic situation where latex yield could be adversely affected. The status of the folial disease of nine clones in a 40ha clonal garden at rubber research institute of Nigeria, main station, Iyanomo, Benin City is reported.

Keywords: Hevea brasiliensis, Filial disease, Diseases severity, Clonal garden.

77

Yield Performance of Controlled Upward Tapping Systems

in Relation to Tree, Land and Labour Productivity

Do Kim Thanh1, Nguyen Quoc Cuong1, Nguyen Duc Tin2

1. Rubber Research Institute of Vietnam

2. Loc Ninh Rubber Company

(Paper presented at IRRDB Annual Meetings and Conference 2007,

12th – 16th November 2007, Siem Reap, Cambodia)

Abstract:

Three controlled upward tapping (CUT) systems which generated from the combinations of downward and upward tapping with variation in length of cut, period of tapping in one year cycle, and frequency of stimulation was tested on mature phase of rubber tree. Yield performance was recorded in four consecutive tapping years. Data was analysed in view of tree, land and labour productivity. Results have showed that all three CUT systems produced rubber yield at above the target of 2,000 kg/ha/year averagely.

The change over tapping system of half spiral downward cut for six months to half spiral upward cut for four months (1/2S¯ 6m/12, 1/2S ­ 4m/12) appears disadvantages on tree and labour productivity. The double cut system of half spiral downward cut for 10 months combined with a quarter spiral upward cut for 7 months (1/2S ¯ 10m/12 + 1/4S­ 7m/12) produces highest yield on GT 1. It is likely unsuitable for PB 235 due to lower yield from the third year of tapping in comparison to the single quarter spiral upward cut. This system needs more labour input to tap rubber tree that leads to low labour productivity. The single CUT system of a quarter spiral upward cut (1/4S ­ 10m/12) brings a balance between tree, land and labour productivity and promising for sustainable yield in long term.

Keywords: Controlled upward tapping, tapping system for mature phase, double cut system.

78

General Situation of Diseases on Rubber Trees in China

F. C. Zheng

Environmental and Plant Protection Research Institute, Chinese Academy of Tropical Agricultural Sciences, Danzhou, Hainan 571737, China

Abstract

Rubber trees in China have suffered from many diseases or disorder. According to our survey, the number of diseases or pathogen-symptom combination on rubber trees accounted for more than 90 (Table 1).

Four top economically important diseases or disorders in rubber trees in China are Powdery Mildew (Oidium heveae), Anthrocnose [Colletotrichum gloeosporioides (imperfect stage), Glomerella cingulata (perfect stage)], Brown Bast (Tapping Panel Dryness) and Root disease [Ganoderma pseudoferreum (Red Root Disease), Phellinus noxius (Brown Root Disease), Poria hypobrunnea (Black Root Disease), Rigidoporus linosus (White Root Disease), Helicobasidium compactum (Purple Root Diseas)]. Powdery Mildew occurred every year in China and resulted in serious premature leaf fall of rubber trees. Anthrocnose was the second important leaf disease, but more and more serious in during years, though it was occasionally spread some years ago. The incidence of Brown Bast is now more or less 15%, and no practical control measure yet. The incidence of Root Diseases is now at least 8% in Chinese rubber plantations. Among the root diseases, the most economically important ones are red and brown ones.

The insignificantly important yet but potentially dangerous disease in Chinese rubber plantations are Corynespora Leaf Fall and White Root Disease. Corynespora Leaf Fall was newly discovered in nursery and still limited to few plantations. White Root Disease was discovered only in one plantation.

Phytophthora diseases of rubber trees include abnormal leaf fall and Black Stripe on Tapping Panel. Abnormal leaf fall of rubber trees has been sporadically distributed in China. Black Stripe on Tapping Panel is now not economically important, though it was serious in Chinese rubber plantations some years ago.

Key words: rubber tree diseases

79

The Study On Clones And Four Different Planting Densities For A Short Planting Cycle Of Hevea In Malaysia1

Mohd. Nasaruddin Bin Mohd2. Aris, Ramli Othman3 and Syolahuddin Mokhter2

Malaysian Rubber Board

1. Paper presented at IRRDB International Natural Rubber Conference & Annual Meetings 2007, 12th – 16th November 2007, Siem Reap, Cambodia

2. Research Officer, Crop Management Unit, Malaysian Rubber Board.

3. Director of Production Development Division, Malaysian Rubber Board.

Abstract

There are two types of clones suitable for a short planting cycle i.e. latex timber clones and timber clones. In addition, results obtained from the rubber forest preliminary clone trial showed that some of the 1995 Hevea germplasm collections were found to be promising. These materials will be further tested prior to recommendation. Four planting densities viz. 500 plants/ha, 1000 plants/ha, 1500 plants/ha and 2000 plants/ha are being studied for rubber forest plantation. Analysis of variance for girth measured at 150 cm (VR = 10.0, p<0.05) and 60 cm from the ground (VR=10.7, p<0.05) showed that there were significant differences among the different planting densities. In order to examine the trend existed with regard to different planting densities and to locate the specific differences that might account for the significance, the trend comparison procedure was used where the sum of square of planting densities was partitioned. The highest degree of polynomial that could be tested was cubic. The results indicated significant linear response indicating that girth decreased proportionately with increment of planting density. The results obtained from a two-way analysis of variance using pooled data of both clones showed that there was significant difference between clones (p<0.05). This was also found for the planting densities. The results obtained from comparison between pair of treatment means using the least significant difference test for RRIM 2020 showed that mean girth at 150cm and 60cm from the ground for planting density of 500 plants/ha were significantly different than that of 1000 plants/ha, 1500 plants/ha and 2000 plants/ha. The test carried out on pooled data indicated that except for planting density pairs of 1000 plants/ha and 1500 plants/ha, there were significant differences among other pairs of treatment means compared. The least significant difference test for RRIM 2025, however, showed that only the girth measured at 150cm and 60cm from the ground for planting density of 500 plants/ha and 1500 plants/ha were significantly different than that of 2000 plants/ha. Girth measurement at the ten year after planting (June 2004) was made in observation plots planted with plants at the density of 1111plants/ha in RRIMinis Niah, Sarawak. As far as wood volume is concerned, the cylindrical wood volume ranged between 0.08 m3 /plant and 0.21 m3 /plant. Treated and kiln dried sawn timber should be considered as far as value added is concerned in rubber wood production.

80

Evaluation of Gaseous Stimulation on Panel BO-21

Muhammad Akbar Abdul Ghaffar2, Mega Arjuna Abang2 and Salihin Sekot2

Malaysian Rubber Board

1 1This paper was presented at IRRDB Annual Meeting and Conference 2007, Sokha Angkor Resort, Siem Rep, Combodia on 12th to 16th November 2007

2 Research Officer, Malaysian Rubber Board, Kuala Lumpur, Malaysia

Abstract

The tree and land productivity of rubber cultivation are much depending on commencing tapping systems based on the age, panels and the concentration of stimulation used and it is already accepted that ethephon and ethephon-based stimulant formulations are suitable for young mature Hevea trees tapped on panels BO-1 and BO-2. An experiment was established to evaluate the response of gaseous stimulation technique on clone RRIM 905 tapped at panel BO-2. During it first year, the gaseous stimulation tapping system were giving higher yield compared with the nil stimulation and non gaseous stimulation tapping system with the highest was obtained from the tapping system of 1/2S d/3 + GF, 1/2S d/3-ns (9:3) by 120 g/t/t. The same also goes with the land productivity with 2083 kg/ha/year. However, for the second and third year, it was observed that the gaseous stimulated tapping systems showed declining trend. During the period, higher tree productivity was obtained from ethephon stimulated trees. A similar observation can be seen with the land productivity for the treatments involved. A record of dryness incidence during the third year shows that the gaseous stimulation have given the highest incidence of dryness with 16.9% was recorded for tapping system of 1/2S d/3 + RF, 1/2S d/3-ns (9:3), the same tapping system that gave the lowest yield during the third year of experiment.

In thông tin
Các thông tin khác:
COPYRIGHT © 2006 BY RUBBER RESEARCH INSTITUTE OF VIETNAM
Business registration Certificate No. 121/TTM-VNNIC dated January 07 2002
Developed by ANDI Software Co.,Ltd