Visitors : 90234
International Natural Rubber Conference 2006
Ho Chi Minh City, November 13-14, 2006

·         17 countries: Cambodia, China, Cote d’Ivoire, France, Guatemala, India, Indonesia, Laos, Malaysia, Myanmar, Netherland, Nigeria, Papua New Guinea, Philippines, Sri Lanka, Thailand, Vietnam.

·         311 participants , in which, 150 participants from overseas

·         93 research papers.

Some considerations concerning the panel management

in rubber tapping (Hevea brasiliensis)


R. Lacote*, O. Gabla**, S. Obouayeba***, E. Gohet*, A. Doumbia**, M. Gnagne*** and J.M. Eschbach*


*: Cirad, UR 34, Tree Crop Based Systems, TA80/B2, 34398 Montpellier, France

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

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


Coresponding author: R. Lacote,




Research devoted to long term panel management deserved less efforts, mainly due to the long duration required for experimentation. The present study deals with the comparison of two panel management strategies on nine clones tapped in 1/2S, over a total period of nine years, in Côte d’Ivoire: annual panel changing and no panel changing. Four IRCA clones were compared to PB 330, GT 1, PB 217 et PB 260. For all clones, panel management influenced the annual yield. During the first six years, panel changing was more favourable to yield. After nine years, however, the cumulative rubber yield did not vary with panel strategy. Only clone IRCA 111 showed a significant higher yield with no panel changing. Authors recommend a panel changing strategy based on physiological fatigue of the tapping panel. The aim is to sustain the yield potential of the trunk and to reduce the tapping panel dryness occurrence during the downward tapping period.


Keywords: Hevea brasiliensis, tapping, panel management, latex yield, tapping-panel dryness (TPD)




Chan Weng Hoong

Advanced Agriecological Research Sdn Bhd, Locked Bag 212, Sungei Buloh Post Office,

47000 Sungei Buloh

Selangor Darul Ehsan, Malaysia



II-           ABSTRACT


One trial each on short cuts was laid down on basal virgin bark and high level virgin bark. The short 1/3S panel changing system was compared with the non-panel changing system on basal virgin panel BO2 in one trial while the short 1/6S^ cut  was evaluated on high level virgin panel HO1in the other trial.


Results at the end of 4 years on the 1/3S cut on showed no difference in mean yield   between the panel changing system and the non-panel changing system.  Both these system however yielded 3-4 percent lower than the 1/2S control yield of 1900 kg per hectare.


Cumulative incidence of dryness of the short cut systems at around 12 percent was marginally lower than the 1/2S control. Bark consumption was higher for the panel   changing system due to increased   consumption of bark on opening of the hardened bark on the annual change-over of panel.


For the trial on high level virgin bark, the 1/6S^ + 1/2S double cut   system yielded 8 percent lower than the 1/4S^ + 1/2S control over 18 months. On the single 1/6S^ treatment, yield per tapper was 6 percent higher but yield per hectare was 32 percent lower than the 1/4S^+ 1/2S control. Incidence of dryness for the both upward cuts was high, ranging from 7.5 percent to 12.8 percent in the first year compared with 3.9 to 4.5 percent for the first year for downward cuts on basal panel BO2. Bark consumption was approximately 56 percent higher for the upward cuts than the downward cut on basal renewed panel B11.


The benefits of short cuts on both basal and high level virgin panels are enlargement of task size, higher yield per tapper and increase in lifespan of trees.


Keywords : Short cuts, basal virgin bark, high level virgin bark, panel changing system, non panel changing system.


Tapping frequency and productivity

on a few smallholdings

in West Kalimantan Province, Indonesia


Jean-Marie Eschbach *, Ilahang **, Caroline Le Foll***, Gede Wibawa ****

and  Eric Penot *


* CIRAD Montpellier, France

** ICRAF SEA, Sanggau, Indonesia

*** ISTOM Cergy Pontoise, France

**** IRIEC/ICRAF SEA, Bogor , Indonesia




Latex production has been monitored on a daily basis, since tree opening in 2003, on 38 farms spread over 5 villages in West Kalimantan province. The purpose of this paper is to describe those practices and link them to the productivity achieved, and to relate them with the different socio-economic contexts in those villages. Substantial variability was found in tapping practices for each village. The farmers were assumed to tap their trees very intensively every day in d/1, with very high bark consumption. However monitoring data showed that in fact, for many of the smallholder plantations, tapping was less frequent and very irregular. Indeed, the annual number of tappings could double from one village to another (67 to 130 days/year) and remained well below the number obtained with a d/1 frequency. The time spent on tapping depended on other farming activities. Tapping frequency was a concept that could not be applied to smallholder farmer at least at Indonesian experience. For many plantations, trees tapped in unstimulated 1/2S were clearly under-exploited. Lastly, as bark is the productive capital of the farmer, we found that bark consumption per tapping was inversely proportional to the number of tappings per village. However, it remained very high, with many wounds. Technical training in tapping organized by ICRAF in June 2005 has helped farmer to improve tapping quality and thereby extend the economic life span of the plantations.






Sungei Putih Research Centre

Indonesian Rubber Research Institute

P. O. Box 1415 Medan 20014





Rubber plant productivity directly related to application of exploitation system. Variation of both recommended and promising rubber clones are necessary to implement specific exploitation system which suitable for optimal production and to avoid any incidence of TPD (tapping panel dryness). The results of recent rubber exploitation research are directed for modifying on upward tapping, arranging of length in tapping cut, tapping frequency, and stimulant application. An optimal stimulation technique is necessary to consider respectively in season, dose, frequency, and application technique. The objectives of this trial were to optimize exploitation system for recommended and promising clones in order to optimal production and to prevent from TPD incidence. The trials were carried out in Bandar Betsy and Bandar Bejambu estates, PTP Nusantara III, North Sumatra, by using the nested block design, and with three replications. Treatment factors were 8 tapping systems and 15 recommended and promising clones. Treatments of exploitation system were various in length of cut between 10 cm to ½ S (spiral) in upward and downward directions, d/3 tapping frequency and combined with several techniques of stimulant application. The clones used were BPM 1, BPM 107, BPM 109, IAN 710, PB 255, PB 260, PB 280, PR 261, RRIC 100, RRIC 102, RRIC 110, RRIM 712, RRIM 717, RRIM 728, and TM 6. The variables observed were rubber production, %-coagulum, dry rubber content, length of tapping cut, total solid content, stem girth, sum of tapping days, sum of effective trees, and the incidence of TPD. The results showed that the high production clones were BPM 109, RRIC 100, RRIC 110, and PB 255 especially in Bandar Betsy estate, while the highest production clones in Bandar Bejambu estate were PB 255, BPM 109, and PB 260. In the both locations, the lowest production clones were PR 261 and TM 6. Optimizing exploitation system for clones’ variation was specifically different, but by using tapping system of ½ S d/3.ET2.5%. La1.18/y(2w) was generally obtained the highest production in those locations. The incidence of TPD was generally still low (0.5 – 4.1%) in each exploitation system. The highest TPD incidence (5.7%) was occurred in control tapping system (1/2 S d/2), then decreased to 4.1% in tapping system of ½ S d/3.ET2.5%.La1.18/y(2w), and followed by any others exploitation systems which gradually decreased. TPD incidence in average for variation of tapping systems was under than 3.2%. However, some exception was occurred in clones of RRIC 100 and RRIM 717 which obtained TPD incidence around 5%.


Keywords: Hevea brasiliensis, productivity, clones, exploitation systems




Samuel OBOUAYEBA*#, Eric SOUMAHIN***, Ayah Marie Chantal BOKO*, 

Michel Yedoh GNAGNE* and Kouadio DIAN**


Agronomy Division, National Agronomic Research Center (CNRA) establishment of Bimbresso

in south east of Côte d’Ivoire


I-                    Abstract


The shortage of skilled tappers is an increasing concern in rubber tree cultivation. A trial was carried out in Cote d’Ivoire in order to overcome this constraint for about 20 years. For tapping systems with increased frequency of hormonal stimulation but reduced tapping intensities, either by a reduction in tapping frequency (½ S d/6 6d/7 ET 5 % 8-10/y) or by a reduction in tapping length cut (¼ S d/3 6d/7 ET 10 % 8-10/y) were compared to the control for the clone PR 107 (½ S d/3 6d/7 ET 5 % 4/y). Rubber trees were assessed for rubber production, bole growth, physiological profile and tapping panel dryness (TPD) occurrence. Results of several years of experimentation showed that the increase in hormonal stimulation frequency compensated partly to fully the reduction in tapping intensity while insuring satisfying bole growths and physiological states of trees, low occurrences of TPD, longer tapping periods resulting in longer economic life of trees. Tapping systems with lower tapping intensity and more intense hormonal stimulation were economically more profitable than the control. Hence, the concern about the lack of skilled tappers in rubber tree cultivation in large estate as well as in smallholdings can be effectively addressed by a reduction in tapping intensity along with an increase in hormonal stimulation.


Discipline : Exploitation-Physiology (Agronomy)

Additional keys words: Clone PR 107 of Hevea brasiliensis, low intensity tapping system,    hormonal stimulation, cut dryness, rarity or dearness of tapper, Côte d’Ivoire.               

* Researcher at CNRA (Centre National de Recherche Agronomique), research center of   

      Bimbresso, 01 BP 1536 Abidjan 01, Côte d’Ivoire

 **Researcher at CNRA Central Laboratory Biotechnology 01 BP 1740 Abidjan 01, Côte d’Ivoire

*** Student at UFR-Biosciences Université de Cocody, Abidjan, Côte d’Ivoire

*,# Corresponding author

CNRA, Station de Bimbresso, 01 B.P. 1536 Abidjan 01 (Côte d’Ivoire) - (225) 05 74 40 55- Samuel OBOUAYEBA  or




Samuel OBOUAYEBA*#, Eric SOUMAHIN***, Ayah Marie Chantal BOKO*, 

Michel Yedoh GNAGNE* and Kouadio DIAN**

Agronomy Division, National Agronomic Research Center (CNRA) establishment

of Bimbresso in south east of Côte d’Ivoire



The growing of Hevea brasiliensis, main origin of natural rubber faced a serious constraint that is dearness or rarity of tappers. To overcome such constraint, exploitation systems that reduce the need for tappers have been experimented on clone PR 107 in Côte d’Ivoire. For this purpose, reduced intensity tapping systems compensated by high stimulation (½ S d/6 6d/7 ET 5 % 10/y and ¼ S d/3 6d/7 ET 10 % 8-10/y) had be tested and compared to actual exploitation system (½ S d/3 6d/7 ET 5 % 4/y) according to production, growth, physiological profile and tapping panel dryness on the nature of the exploited bark and the orientation of the tapping. Agronomic and physiological results show that the reductions of tapping intensity are not always compensated by the high stimulation. Best alternatives to the reference system reduced from 10 to 50 % the need of tappers and mitigated shortage and/or the expensiveness of the labour. These alternatives exploitation systems are downward tapping on first renewal bark (BI) ½ S d/6 6d/7 10/y; upward tapping on virgin bark (HO) ¼ S d/3 6d/7 10/y; downward tapping on second renewal bark (BII) ¼ S d/3 6d/7 8-10/y and during the experiment, ¼ S d/3 6d/7 10/y. This study is good opportunity to suggest, apart from nature of exploited bark and the king of tapping, the application of profitable compensative exploitation systems evidenced for smallholding rubber tree plantation in the future.

Discipline: Exploitation-Physiology (Agronomy)

Additional keys words: Downward and upward tapping systems ; first renewal bark; second renewal bark ; virgin bark ; agronomic and physiological parameters ; shortage and/or dearness of tapper, low intensity tapping systems


* Researcher at CNRA (Centre National de Recherche Agronomique), research center of   

       Bimbresso, 01 BP 1536 Abidjan 01, Côte d’Ivoire

**Researcher at CNRA Central Laboratory Biotechnology 01 BP 1740 Abidjan 01, Côte d’Ivoire

*** Student at UFR-Biosciences Université de Cocody, Abidjan, Côte d’Ivoire

*,# Corresponding author


Preliminary results of the application of ethylene

gas stimulation (RRIMFLOW) in Vietnam


Do Kim Thanh*, Nguyen Thi Hoang Van*, Nguyen Nang*

Nguyen Thi Hue Thanh** and S. Sivakumaran***


*   Rubber Research Institute of Vietnam

**   Dong Nai Rubber Company

***  RCP Technologies Sdn Bhd, Malaysia


     KEYWORDS: Latex stimulation, Gaseous stimulation, RRIMFLOW




RRIMFLOW exploitation technique (RF) is first introduced in 2005 with the main aim to maximize yield of rubber tree. It is needed to carry out the adaptive research to ensure the successful application in substantial Vietnam condition. In line of this, two basic experiments were conducted to study the yield performances of RF system in comparison with current commercial tapping systems. The RF system produces higher tree productivity ranging from 20% to 50% over the commercial tapping systems of double cut and half-spiral upward cut. Monthly rubber yield of RF system is more stable at high level during tapping year cycle, whereas the control system shows low yield at the beginning and only reaching the full potential during peak yield period. Higher productivity per tree leads to higher land and tapper productivity. Lower DRC is recorded for RF system in comparison to control mainly in the heavy rainfall period, which leads to the suggestion of reduction gassing frequency. It is apparently that RF system has higher ratio of dryness despite of most of new cases come from previously dryness on basal cut.

Yield response to RF is an attribute of rubber clone. RRIM 600, PB 235, RRIC 121, RRIC 100, GT 1 and RRIC 110 are good responders. RRIM 712 shows lower response to RF. Dry rubber content of RRIM 712 and RRIC 100 are relative low, which might lead to reduction of gassing frequency.




V.H.L.Rodrigo, K.V.V.S. Kudaligama and R.K. Samarasekera

Rubber Research Institute,

Dartonfield, Agalawatta, Sri Lanka




With no success in mechanised tapping, the Low Frequency Tapping (LFT) systems are found to be the only option available to address the main issues in the rubber tapping such as shortage of tappers, high level of cost on tapping, poor earnings of tappers and high level of bark consumption reducing the lifespan of rubber tree. Ethylene gas is an effective stimulant in LFT and those gaseous stimulated tapping (GST) systems are considered to be successful in addressing above issues with high yields given and reduced bark consumption. However, no systematic studies on these systems have been conducted with the clones developed in Sri Lanka. Therefore, the present study was aimed to assess the effectiveness of the gaseous stimulation in tapping with Sri Lankan clones under local conditions. A GST system was set up in the Rubber Research Institute of Sri Lanka (RRISL) in six tapping blocks with two clones and also in another six estates at different scales as stakeholder collaborative trials. The tapping system of 1/8S(↑) d/3 ET(G) 1/10d was applied except for two tapping blocks, one from each clone in the RRISL where 1/8S(↓) d/3 ET(G) 1/10d was tested. With initial observations made for two months, the frequency of tapping and gassing of GST was reduced in the experimental site of the RRISL leaving two tapping blocks as originally set up for upward and downward tapping. Data on latex yields were continuously monitored where possible with the records on bark conditions.


With few exceptions, latex yields were very high with the GST at the beginning and thereafter tended to decline and in some cases, up to the values recorded in the control blocks with the traditional tapping system. Yields given by the downward tapped GST was comparable with that of the control tapping blocks, particularly in the clone RRIC 100.  The percentage dry rubber content of the latex (%DRC) also dropped with the application of gaseous stimulation and fell below 30%, except in the clone RRIC 121.  Bark wounds connected with bark rotting were developed in some trees of all GST blocks and in some cases, this was associated with borer attacks. However, the above bark deterioration appeared to be less severe in occasions where gassing frequency was reduced. Number of trees affected with Tapping Panel Dryness (TPD) was greater in the GST blocks when compared to that recorded in the control blocks. Therefore, the present study emphasizes the needs of further investigations to identify suitable intensities of tapping and gassing with GST, if it is to be applied under Sri Lankan conditions.


Key words: Ethylene, Gaseous stimulation, Low frequency tapping





S. Hav and C. Chhek

Cambodian Rubber Research Institute (CRRI)

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


R. Lacote


UR 34, Tree Crop Based Systems, TA80/B2, 34398 Montpellier, France





Cambodian Rubber Research Institute is carrying out researches on tapping systems to assess the influence of intensity of stimulation on yield at a given tapping frequency 1/2S d/3 7d/7. The objectives of these trials are to determine the yield potential of each clone at various intensity of hormonal stimulation. Five clones have been studied since March 2005. These clones are IRCA111, PB330, GT1, IRCA230 and AF261. Each trial consists of Fisher block design with 3 replications and four treatments per replication. Two protocols of stimulation were set up for different clones. The preliminary results show that the highest yields for the clone IRCA111 and PB330 are obtained with ET 1.5% Pa 1(1) 5/y (75 mg) and ET 2.5% Pa 1(1) 2/y (50 mg), respectively. Interestingly, the clones GT1 and IRCA230 give significant high yield at the most intensive treatments, ET 2.5% Pa 1(1) 6/y (150 mg). However, the clone AF261 does not response to more intensive stimulation system than ET 1.5% Pa 1(1) 5/y as the same yields are obtained at different intensities of stimulation. The clone GT1 gives the highest yield at increased stimulation intensity compared with other clones.


Keywords: Hevea brasiliensis, clones, yield potential, Cambodia.




Samuel OBOUAYEBA*#, Eric SOUMAHIN***, Ayah Marie Chantal BOKO*, Bernard Dea GOUE****,  Michel Yedoh GNAGNE* and Kouadio DIAN**

Agronomy Division, National Agronomic Research Center (CNRA) establishment of Bimbresso in south east of Côte d’Ivoire





In smallholding 9 to 12 years of downward tapping on virgin bark are followed by downward tapping in renewed bark, with the result that the whole period of exploitation can barely exceed 20 years, whereas in industrial plantations, the introduction of upward tapping enables up to 36 years of exploitation. An experiment was set up in order to evaluate the feasibility of upward tapping in smallholding conditions in four locations. Downward tapping on renewal bark  (½ S d/3 6d/7 Et 2,5 % pa 1/1 10/Y) was compared to upward tapping on virgin bark : ¼ Sr d/3 6d/7 Et 5 % pa 1/1 10/Y  and ½ Sr d/6 6d/7 Et 2,5 % pa 2/1 10/Y. Tapping systems performances were assessed for rubber production, vegetative growth, physiological profile and the tapping panel dryness susceptibility of rubber trees. The productivity of the downward tapping, on first renewal bark, is satisfactory, but significantly lower than productivities of upward tapping systems on virgin bark. Compare to downward tapping on renewed bark, upward tapping on virgin bark increase the productivity of rubber tree of about 34 % for the quarter spiral and 36 % for the half spiral. Globally, the physiological profile of all tested systems are good, with little occurrence of tapping panel dryness. These results show that the upward tapping on virgin panel, especially the upward quarter of spiral, is the best tapping system of trees in smallholding. 


Keywords: Improvement, Côte d’Ivoire, tapping systems, virgin bark, renewal bark, smallholdings, productivity, physiological profile, tapping panel dryness.  

* Researcher at CNRA (Centre National de Recherche Agronomique), research center of   

 Bimbresso, 01 BP 1536 Abidjan 01, Côte d’Ivoire

**Researcher at CNRA Central Laboratory Biotechnology 01 BP 1740 Abidjan 01, Côte d’Ivoire

*** Student at UFR-Biosciences Université de Cocody, Abidjan, Côte d’Ivoire

**** Researcher at CNRA (Centre National de Recherche Agronomique), research center of   

      Korhogo, 01 BP 1740 Abidjan 01, Côte d’Ivoire

*,# Corresponding author

CNRA, Station de Bimbresso, 01 B.P. 1536 Abidjan 01 (Côte d’Ivoire) - (225) 05 74 40 55- Samuel OBOUAYEBA  or



 FOR GT 1 AND PB 235


Phan Dinh Thao*, Do Kim Thanh* Nguyen Ngoc Kieng** and Mai Van Son*

(*) Rubber Research Institute of Viet Nam,

(**) University of Agriculture and Forestry, Ho Chi Minh City





A study on the establishment of models was carried out for the prediction of yield performance of rubber plantation. Data recordings of two popular clones GT 1 and PB 235 were calculated following the linear and non-linear regression analyses to get the best-fit model based on the highest correlation coefficient and level of statistical significance. The results showed that, in this study, the relationship of age of tapping (x) and   individual   yield   (y) can be expressed   by   lny = b0 + b1lnx model; whereas age of tapping (x) and density of tapped tree (y) followed the lny = b0 + b1lnx + b2(lnx)2 model. Yield per hectare (y) in relation to age of tapping (x1) and density of tapped tree (x2) can be expressed by lny = b0 + b1lnx1 + b2lnx2 model. In connection with these models, it is required the knowledge on agronomy, exploitation system such as position of tapping cut for slightly adjusting the yield prediction.


Key words: yield production, hevea yield modeling


The study of the use of Southern Oscillation Index to anticipate long dry season in the two estates with contrasting climatic conditions


Thomas  Wijaya

Indonesian Rubber Research Institute

Sembawa Research Station

PO Box 1127, Palembang 30001, Indonesia





Long dry season due to El-Nino phenomenon occurs periodically and causes reduction in farmer income. Information on timing of long dry season is important for crop management such as time of planting, fertilizer application, and irrigation.  When the long dry season occurs, usually, monthly SOI values were consecutively negative.  SOI describes the normalization of the difference air pressure between Tahiti and Darwin.  SOI has been used intensively in Australia to predict rainfall and crop production, however it was not yet known whether SOI could be used for Indonesian environments.


The research and experience for the last few decades showed that El-Nino was play a big role in occurrence of long dry season in Australia and other countries. Not all regions in Indonesia experience the same severity of long dry season due El-Nino.


The study of the use SOI to predict long dry season was carried out at two estates at Pagar Alam (South Sumatra) with average annual rainfall of 3031 mm and Way Lima (Lampung, province) with average annual rainfall of 1787 mm.  Lag correlation between SOI and rainfall was conducted and also empirical soil water balanced was carried for long-term period of time. The soil water balance calculation showed that in El-Nino years, the amount of rainfall was reduced in both estates and resulted in reduction of soil moisture index (the ratio actual to potential evapotranspiration). The reduction soil moisture index at Way Lima was greater or experience with more severe drought compared with Pagar Alam due to less rainfall at Way Lima.


There was significant correlation between average three monthly SOI with the total rainfall in the subsequent 3 months for period of June-August, July-September, August-October and September-November for Pagar Alam estate, and period of July-September, August-October and September-November for Way Lima estate. In general, the amount of rainfall decreased as SOI became more negative. The regression equation between rainfall and SOI can be used to predict 3 monthly subsequent rainfall because SOI was available or provided by many meteorological websites


Key words: Southern Oscillation Index, drought, and prediction


Water Status and Radiation Environment in Rubber (Hevea brasiliensis) Systems: A comparison between monoculture and mixed rubber-Acacia mangium plots


Ni’matul Khasanah1), Thomas Wijaya2,*), Gregoire Vincent3), Meine Van Noordwijk1)

1) WorldAgroforestryCentre-South East Asia Regional Programme (ICRAFSEA) P.O. Box 161, Bogor 16001, Indonesia

2) Indonesian Rubber Research Institute, Km. 29, Palembang – Sekayu, P.O. Box 1127, Palembang 30001, Indonesia

3) Institute de recherche pour le développement (IRD) – Montpellier 34398, France

*) corresponding author





Interplanting of Acacia mangium within Hevea brasiliensis plot may be an attractive option for smallholder rubber farmers in the tropics to increase their land productivity. Indeed, economic prospect for timber is good as timber resource in natural forest has become severely depleted and particularly so in Sumatra where this study is conducted.


A. mangium being a very fast growing tree species, careful timing and management of A. mangium is probably required to reduce light competition with rubber trees.  Furthermore a large portion of rubber planted area in Indonesia is subject to two or more dry months during which rubber may shed its leaves and stops its growth. Competition for water use between trees species in periods of low rainfall may be another constraint to growth of the rubber tree. When soil water is gradually depleted trees can maintain their transpiration rates if they can continue to function at more negative plant water potential. At equal rooting patterns, the trees with the almost negative plant water potential will win the contest for remaining soil water.


This study compares a series of growth and physiological parameters measured on rubber trees grown either in monoculture (6 x 3.3 m and 6 x 2 x 14 m) or associated with A. mangium (3 x 3 x 17 m). In the fifth year after plot establishment, variation in the growth of rubber was analyzed in relation to leaf water potential and light interception by canopy. Leaf water potential was used as an indicator of plant water status, but also as indicator of competitive strength. Predawn leaf water potential of rubber trees grown in mixed systems or in monoculture plantation did not significantly different in the beginning of dry season. However, the girth and canopy size of rubber trees grown in mixed systems with A. mangium was significantly smaller. Leaf water potential of A. mangium was more negative than that of rubber in the mixed system, but not as negative as that in a monoculture of A. mangium (where A. mangium trees were competing conspecifically rather than with rubber). Better growth of A. mangium in the mixture than in monoculture can thus have above as well as belowground explanations. The net effect of A. mangium on depressing rubber growth, however, is likely to be primarily caused by shading.


Keywords: intercrop systems, leaf water potential, light intercepted by canopy, tree growth





Kessarin Tungngoen1, Soulaiman Sakr2, Panida Kongsawadworakul3, Unchera Sookmark3,

 Jarunya Narangajavana1 and Hervé Chrestin4


1 Department of Biotechnology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok, Thailand.

2 UMR 547-PIAF, site des Cézeaux, Université Blaise Pascal, 24 avenue des Landais, Aubière Cedex, France.

3 Department of Plant Science, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok, Thailand.

4 Institut de Recherche pour le Développement (IRD) / Department of Plant Science, Faculty of Science,

Mahidol University, Rama 6 Road, Bangkok, Thailand.






Latex flow, the first limiting factor of rubber yield, is linked to latex viscosity, which is inversely related to its water content. Further, yield stimulation with Ethrel has been shown to induce an early influx of water in the latex cells, leading to extension of the bark drainage and displacement areas. Furthermore, preliminary ecophysiological studies on rubber tree Trunk Phloem Necrosis (TPN) showed that the diseased trees exhibit higher water potential, indicating they are facing some water stress. All these data confirm the importance of water exchanges between the different organs and tissues of the rubber tree, especially between the laticifers and the phloemic tissues, they are embedded in. But water cannot freely cross the biological membranes. Aquaporins are channel proteins known, in all living species, to facilitate water fluxes across the cells membranes. Two major aquaporin families are known in plants: the plasma membrane aquaporins (referred as the Plasmalemma Intrinsic Proteins: PIPs) and the tonoplast aquaporins (Tonoplast Intrinsic Proteins: TIPs).


To investigate the possible role of aquaporins in relation with rubber yield and bark physiological diseases, eight different full-length cDNAs encoding phloem and laticifer specific PIPs and TIPs were cloned and characterized in this study. The nucleotide sequences of all full-length cDNAs ranged from 1 to 1.4 kb and encoded different sizes of proteins varying from 25 to 31 kDa. The deduced amino acid sequences of proteins showed significant similarities to PIPs and TIPs subfamily members from other plants. Northern blot analysis showed that the subclass PIP-1 and PIP-2 genes were overexpressed in the phloemic tissues of diseased trees. In contrast, the subclass TIP was significantly overexpressed in healthy trees. Quantitative real time PCR technique was used to elucidate the function of each individual aquaporin isoform. All of these isoforms showed up-regulation in the phloemic tissues of diseased and wounded rubber trees. Each isoform was differentially expressed in healthy trees depended on tested rubber tree clones. While HbB_TIP1 was up-regulated in all clones, marked up- or down-regulation of HbB_PIP1;1, HbL_PIP1;3, HbB_PIP2;1 and HbL_PIP2;3 were observed. More details of aquaporin isoforms and the effect of bark treatment with Ethrel to their expressions are under investigation to clarify their roles in the rubber trees.


Keywords: Aquaporin, Plasma Membrane Intrinsic Proteins (PIPs), rubber tree, Tonoplast Intrinsic Proteins (TIPs), Trunk Phloem Necrosis (TPN).



Proteomics research on the membrane proteins

of rubber particles in Hevea brasiliensis


Duan Cuifang   Nie Zhiyi   Liyu   Zeng Rizhong

Rubber Research Institute /Ministry of Agriculture Key Lab for Tropical Crops Physiology, CATAS,

Danzhou, Hainan 571737, China


This project was supported by the Scientific & Technological Fund of CATAS 2005), and Rubber Research Institute /Ministry of Agriculture Key Lab for Tropical Crops Physiology, CATAS, China (2005)




Rubber particles are important organelles in latex to carry out the rubber biosynthesis in rubber tree. The crucial enzymes in rubber biosynthesis such as rubber transferase, rubber elongation factor and other proteins etc are all located at the surface or embedded in the membranes of rubber particles.

The proteome analysis by 2-DE is one of the most potent methods of analyzing the complete proteome of cells, cell lines, organs and tissues in proteomics studies. It allows a fast overview of changes in cell processes by analysis of the entire protein extracts in any biological and medical research projects.

In this research, we have used a proteomic approach to identify new proteins involved in rubber biosynthesis in rubber particle membrane, and further to find the mechanism of jasmonic acid (JA) and ethylene (ET) acting on the rubber biosynthesis. Firstly, three samples of rubber particle membrane proteins were isolated respectively from latex with JA treatment, ET treatment, and non-treatment (controlled, CK) in rubber tree; and further examined by SDS- PAGE (10% w/v gel). Afterwards, two-dimensional electrophoresis (2-DE) was performed using the nonlinear 17cm IPG gel strip, pH3-10, to separate the membrane proteins and each sample was performed with three repeats for the correctness. Approximately 824 spots were visualized in each silver-stained gel. And results were compared among three samples (JA, ET, CK) in pairs. Subsequent excisions of 524 distinctive spots from the gel of non-treatment sample were digested with trypsin and processed for MALDI-MS for MS fingerprinting. Up to now, 324 protein spots have been identified. Meanwhile, protein spots with differential intensity over 3 times between JA and Controlled, ET and JA, ET and CK samples were directly cut out of gels and processed for MALDI-MS and nano-LC-ESI-MS/MS analysis separately.

The results are as follows:

1.  Approximately 824 spots were visualized in each silver-stained gel of CK samples. So far 324 distinctive proteins spots have been analyzed by MALDI-TOF MS; and the result indicated that 324 protein spots corresponding to about 160 different proteins were identified; Among of these proteins, REF (rubber elongation factor) accounted for 28%; SRPP (small rubber particles) accounted for 6%; The function of other proteins turned out to be energy production (2.3%), transcription, protein synthesis, transport, folding and turnover (3%), cell cycle, apoptosis and oxidative stress (3%), signal transduction (8%), cytoskeleton, and cell movement (10%), metabolism (6%) , rubber allergic protein Hev 3 etc , and unknown function (10%). Though as many as 43% of the proteins identified have been previously described as being expressed in H. brasiliensis, the present data provided an important clue towards determining the function of these proteins and opens up the possibility to perform additional experiments involved in rubber biosynthesis etc.

2.  The comparative analysis of paired samples between JA and CK indicated that 43 protein spots showed significant differences in expression level between JA-treated and CK samples. Among the 43 protein spots analyzed, 22 proteins spots were up-regulated over 3 times by intensity, 12 new protein spots were induced by JA, whereas 2 proteins spots were down-regulated, 7 proteins spots were repressed completely by JA.

3.  The comparative analysis of paired samples between ET-treated and CK samples indicated that 32 protein spots showed significant differences in expression level. Among the 32 protein spots analyzed, 12 proteins spots were up regulated over 3 times, 6 new protein spots were induced, whereas 14 proteins spots were repressed totally by ET.

4. The paired comparative analysis between JA-treated and ET-treated samples indicated that 22 protein spots showed significant differences in expression level. Among the 22 protein spots analyzed, 8 proteins were up-regulated in JA treated samples 3 times more than in ET treated samples, whereas 10 proteins were occurred only in JA treated samples, 4 proteins were occurred only in ET treated samples.

5. Although 43% proteins have been already described by previous proteomic or transcriptomic studies, or are already known to be expressed in H. brasiliensis, this experiment revealed some new proteins differentially expressed after treated with JA or ET (still in identification).

From the silver stained gel, it could be seen that REF accounted a large amount, which showed that REF might have a very important function in the rubber biosynthesis. The expression and protein modification about REF were being confirmed by Western blotting. JA and ET responsive proteins on the membrane of rubber particles implied that JA and ET might regulate rubber biosynthesis through these responsive proteins on the membranes of rubber particles in H. brasilensis (rubber tree).

Our results demonstrate the potential of proteomics analysis of rubber biosynthesis and provide important insight into the regulation of rubber biosynthesis and other related cellular functions.


Key words: Hevea brasiliensis, rubber particle, membrane protein, 2-DE, MALDI-TOF proteomics research, jasmonic acid, ethylene.


Ethepon-induced specific Proteins

on Several Rubber Plant (Hevea brasiliensis Muell. Arg)


Sumarmadji1, Radite Tistama1, Siswanto2


1 Sungei Putih Research Centre

2 Indonesian Biotechnology Research Institutes of Crops




Generally, rubber plants have positive response to etephon (CEPA) treatment. It was marked by increasing of the duration of the latex flow, and therefore to increase the total latex production at certain period. Many proteins which involved in regulation of physiological mechanism could be detected by latex analysis. The research was conducted to obtain ethephon-induced specific proteins in latex. Each clone was treated by three of different exploitation namely ½ S d/2 as control, ½ S d/3.ET2.5% and ½ S d/3.ET5.0%.The analysis provides C-serum and lutoid fraction from latex of each clone that has different response to stimulant. Many clones have a different respons to stimulant that observed in the same period. The result showed that an induced protein (polypeptide) of 27 kDa was in iceferous cell due to the exploitation treatment. In the less responsive clones (BPM1 and GT 1) showed that increasing of 27 kDa protein was occurred if the treatment was 1/2  S d/3.ET5.0%.  While, in the responsive clones (AVROS 2037 and PR 261) showed that increased at 1/2 S d/3.ET 2.5%, but it decreased at 1/2 S d/3.ET5.0%. The function 27 kDa protein was suggested to an antagonist with the proteins which have a role water influx into latex vessel tissue. Lutoid fraction analysis presented at least seven proteins with various molecular weights (30, 35, 37, 40, 56, 70 and 88 kDa). However, by the IEF and 2-D elution analysis it was consistently just found two proteins of  35 kDa and 70 kDa at pHi 5,8. The proteins were suggested have a role in mechanism of latex regeneration and coagulation.


Key word: Hevea brasiliensis, SDS-PAGE, Latex, ethephon, specific protein


Current status of TapPing Panel Dryness

in some Sri Lankan high yielding clones of rubber

and associated factors


A.M.W.K  Senevirathna

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





The severity of the physiological disorder of tapping panel dryness (TPD) of rubber varies depending on a number of intrinsic and extrinsic factors including the genotypic variation. This project attempted to identify the significance of tapping panel dryness in latex production of extensively grown new clones in Sri Lanka and its key determinants at different stages of exploitation with respect to the genotype, and to find possible remedies to minimise or overcome this disorder. The project consisted with a survey in TPD of some popular clones grown in the country, regular monitoring of some selected fields of the same clones to investigate trends in the incidence of TPD and an analysis of bark sugar contents of affected and unaffected trees.


The survey done for RRIC 100, 102, 121 and 130 rubber clones showed that % TPD has increased generally with the advancement of the tapping panel from A (B0-1) to D (B1-2); in other words, it was high when tapping is done in renewed bark compared to that in virgin bark. Also, the TPD incidence increased with age, immature period, girth of plants, yield and with increasing the tapping frequency. Generally, the TPD percentage (Partial + Full) was high in RRIC 100 (22.5%) and RRIC 102 (19.7%) clones compared to the other clones surveyed. However, the severity of the disorder was high in RRIC 130 (about 30%) even in the first virgin panel once the recommended tapping frequency is exceeded. On average in any clone, 40% of the dry trees were with a partial dryness. The estimated average yield loss per tapping panel of RRIC 100, 102, 121 and 130 were 18.7, 14.5, 14.3 and 13.8%, respectively.   


External morphology of TPD affected trees showed that majority of trees were without extra features (52%), whilst very few (3%) was with abnormal out growth on the trunk and the rest with bark necrosis, according to the survey. However, regular monitoring of TPD from the beginning of tapping showed some other four categories such as throughout fully dry, throughout partial dry, conversion of partial to full and recovered trees. In general for any clone, recovery was around 20% and the conversion of partial to full was 8% higher than the recovery during tapping is done in the first virgin panel.


Analysis of sugars using High Performance Liquid Chromatography (HPLC) showed that sucrose content of TPD affected trees are high compared to that in healthy trees. Furthermore, TPD incidence was high in shallow areas where water logging and occasional floods occur. These areas should be avoided in planting of rubber in future to avoid high incidence of TPD. Good quality planting material should also be used to minimise the immature period and the implementation of low frequency tapping systems should be adapted to minimise this disorder.




Hartmann C. a, Lesturgez G.b, Do F. b, Maeght JL.b, Isarangkool S.c and Nandris D.d

a) IRD-Ecole Normale Supérieure (ENS), Laboratoire BIOEMCO, Paris, France

b) IRD-Land Development Department (LDD), Bangkok, Thailand

c) University of Khon Kaen (KKU), Faculty of Agriculture, Thailand

d) IRD-Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), CNRS, Montpellier, France





For decades, a biotic causal agent was suspected to be responsible for rubber tree Bark Necrosis, now called Trunk Phloem Necrosis (TPN). Recently, the physiological status and the multifactorial causes for this complex disease were understood after a pluridisciplinary study undertaken in African estate plantations. In 2005, a new research programme focussing on TPN ecology was started to understand the links between the environment and outbreaks of TPN. This research programme is underway in Northeast Thailand which, although currently considered to be a marginal rubber tree growing zone, is representative of constraining zones where rubber tree plantations will probably be established in the near future.

In 2005, preliminary surveys of rubber tree plots in Khon Kaen region led to the selection of two young rubber tree (RRIM600) smallholder plantations corresponding to different environments: Tiklang (TLG, rainfall: 1100 mm) and Satuk (STK, rainfall: 1300 mm). In order to break free from the former "couples" analyses (TPN affected tree vs. healthy tree) performed in our previous African plantations network, detailed surveys and mapping of diseased trees and global soil characterization were undertaken at plot scale (thousands of trees). The physical status of the soil was assessed by penetration resistance along metric grids, a description was made of soil profiles, and soil porosity and moisture were measured (sampling with a Burger cylinder auger), etc.

Significant differences were recorded between the two plots. In TLG, the distribution of TPN-affected trees and the pedological layer were shown to be non homogeneous within the plot. In comparison with healthy trees, diseased trees were located in shallower soils which were more resistant to penetration and where soil moisture was lower. The structural & physical heterogeneity of the soil was statistically correlated with the spatial distribution of TPN trees in areas with more compacted soil. This result confirms the conclusions drawn after our previous African surveys.

Similar investigations were performed at plot scale in STK where the soils are more sandy and deeper than in TLG. Despite apparently homogeneous soil characteristics, mapping of soil resistance to penetration evidenced a mosaic of 4 different situations: i) highly resistant soils with affected trees, and ii) without affected trees; iii) soft soils with affected trees, and iv. without affected trees. These configurations are currently being studied to identify the stress factors that lead to outbreaks of TPN, but also to identify the protective mechanisms that allow rubber trees to stay healthy in non-soft zones. In particular, we needed to elucidate whether high resistance to penetration resulted from localised low water content or from degradation of the soil structure caused by the use and abuse of mechanical tools. Recent samplings in the 4 situations studied confirmed that high resistance to penetration is not linked to localised low water content or to low porosity, but mainly results from the soil structure.

These results concerning the soil physical status within rubber tree plantations in NE Thailand led us to consider a given planted block as a heterogeneous surface reflecting previous soil physical constraints. Further studies including the dynamic of water stock vs. seasons, soil chemical characterization, root-mapping, assessment of microfauna activity, etc., in relation with in-depth ecophysiological investigations will help clarify the functioning of the soil/roots/trunk continuum that, undoubtedly, plays a major role in outbreaks of TPN.


Keywords: rubber tree, Trunk Phloem Necrosis (TPN), Thailand, loamy soils soil/tree interface, soil resistance to penetration, spatial distribution, bulk density, soil porosity, soil water.


Rubber tree Trunk Phloem Necrosis (TPN) in Northeast Thailand: 2. within-stand characterisation of affected trees


Frederic C. Do1, Alain Pierret1, Pierre Couteron2, Gregory Lesturgez1, Supat Isarangkool Na Ayutthaya3, Junya Junjittakarn3, Santimaitree Gomkhadee3, Jean-Luc Maeght1, Christian Hartmann1, Krirk Pannengpetch3 and Daniel Nandris4


1 Institute of Research for Development (IRD), Land Development Department, Chatuchak, Bangkok, Thailand

2 French Institute of Pondicherry, Ecology Department, Pondicherry, India – UMR AMAP, Montpellier, France

3 Faculty of Agriculture, University of Khon Kaen (KKU), Thailand

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





The main aim of this work was to identify how outbreaks of Trunk Phloem Necrosis (TPN) in rubber trees could originate from environmental stresses. At Satuk, in a dry area in Northeast Thailand, data was collected on tree girth, girth increments and the occurrence of TPN and Tapping Pannel Dryness (TPD) in a young stand of rubber trees (RRIM 600) that had been tapped for three years. For spatial statistics, we used the framework of marked point processes patterns analysis considering diseases as binary marks, and diameters or tree basal area as quantitative marks, and computed second order statistics of the spatial distribution of marks with Monte-Carlo tests using random reallocations of the marks.

First of all, a relatively small average girth (49 cm) and slow girth increment (1 cm.yr-1) reflected overall high environmental and exploitation constraints. For a total of 2531 exploitable trees, the incidence of TPN and TPD was 7.6 and 5.9 %, respectively. The average girth of TPN trees (52 cm) was significantly larger than that of TPD and healthy trees (which did not differ significantly from each other). In addition, the girth of healthy trees that were immediate neighbours of TPN trees was significantly smaller than that of other healthy trees. The annual girth increment of TPN trees was larger than that of TPD and healthy trees. This difference likely resulted from the fact tapping had stopped and could partly explain the difference in girth between TPN and healthy trees. The spatial distributions of TPD-affected and TPN-affected trees were not random. Diseased trees frequently formed small clusters of two or three trees (5-10 m radii). Moreover, the clusters of TPN trees were preferentially located within zones of trees with a larger basal area than average, with a maximal distance of aggregation of up to 20 m. This was not the case for TPD trees.

From these results, we infer that, prior to disease outbreak, the girth of TPN affected trees is almost systematically equal to or larger than healthy trees. Hence, it seems unlikely that TPN affected trees are individuals exposed to environmental stresses from the earliest developmental stages. Rather, we propose that environmental constraints mainly contribute to the occurrence of TPN through a punctual  stress at maturity. The spatial distribution of TPN tree suggests that inter-individual competition is involved in the emergence and extension of the syndrome within the stand. Inter-individual competition may heighten the effects of punctual  water stress when a short dry spell occurs during early stages of tapping


Keywords: rubber tree, stand, dryness, tree girth, spatial analysis, inter-individual competition.


Measurements of rubber tree transpiration

in adult plantations


M. Verdier, O. Roupsard, P. Thaler, A. Chantuma, P. Siripornpakdeekul, P. Kasemsap, K. Sangkhasila.




In order to assess water balance of rubber plantations at plot scale, accurate dynamic measurements of tree transpiration is required.

Sapflow was measured in a 12 years old plantation (RRIM 600) in eastern Thailand, by heat dissipation method (Granier 1985, 1987) using home-made 20 mm-long radial probes, continuously heated (0.2 W), and connected to a data logger. The calibration of the home-made probes was checked in the laboratory with reference to the gravimetric method.

We adjusted the experimental devices to rubber field conditions and evaluated the different sources of variability to design the appropriate monitoring process.

Natural thermal gradient was not significant. Vertical variation along the trunk below canopy was low. Conversely a significant azimuthal variation was recorded, though without specific trend. Accordingly 2 probes (one on the North face, one on the South face), located above the tapping panel were used for monitoring.

Radial distribution of sapflow was recorded, using a long probe, and our results showed significant variations of sapflow along the radius. A function was derived from these radial variations to estimate total tree sapflow from measurements within the outer 2 cm of sapwood.

Finally to evaluate stand transpiration (mm h-1), trees were sampled according to trunk diameter. Such data will be used to partition evapotranspiration measured on the same plot by eddy-correlation between tree transpiration, T, and soil and understorey evaporation, E.


Key-words: Sapflow, transpiration, field monitoring.


Carbon, water and energy balance

of rubber ecosystem


Philippe Thaler1, Jessada Patharalerpong2, Pongpan Siripornpakdeekul2, Poonpipope Kasemsap3, Olivier Roupsard1, Arak Chantuma4 and Jean-Marc Bonnefond5


1 Cirad, UR Plantation Ecosystems, DORAS Center, Kasetsart University, 10900 Bangkok, Thailand

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

3 Department of Botany, Faculty of Science, Kasetsart University, 10900 Bangkok, Thailand.

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

5 INRA, UR EPHYSE, Bordeaux, France.




Carbon sequestration potential of rubber plantations may provide opportunities to increase the profitability and acceptability of plantations. Thus, carbon exchange of the plantations has to be assessed accurately.

A complete system has been installed in eastern Thailand (Chachoengsao Rubber Research Center, RRIT-DOA) in 2006. Carbon fluxes of rubber plantation ecosystem are continuously measured by eddy-correlation method (CO2 exchanges between the ecosystem and the atmosphere). Evapo-transpiration (ETR) are measured by eddy-correlations and water balance together and partitioned between tree transpiration and soil evaporation. Meanwhile, amounts of C stored in the trees will be evaluated by measuring biomass increment along the life cycle of the plantation, in combination with estimations of the carbon content of the different compartments. These measurements will provide the annual balance of C within plantations at different ages. Energy balance will be assessed by measurements of net radiation (Rn) and estimation of energy partitioning among heat fluxes and heat storage.

Results obtained at ecosystem scale by these methods will be compared to gas exchanges measured at the level of the different compartments (canopy, trunk, root system, soil…).

Thereby, 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.


Techniques for studying the transportation of jasmonic acid in  Hevea bransilinsis


Shi Minjing  Chen Yueyi  Tian Weimin

Ministry of Agriculture Key Laboratory for Tropical Crops Physiology/Rubber Research Institute,

China Academy of Tropical Agriculture Science,

Danzhou, Hainan 571737, China





An attempt was made to develop techniques of autoradiography in paraffin section and indirect immunofluorescence localization to explore the transportation of exogenous jasmonic acid in the rubber tree (Hevea brasiliensis Mull.Arg).

Jasmonic acid is an important and novel plant hormone. At present, transportation of jasmonic acid in plant was rarely studied for the difficulty in fixing jasmonic acid. Some reagents were found to resolve the problem in investigating the transportation of jasmonic acid in rubber tree.

By using autoradiography in paraffin section, the distribution of 3H-JA was identified. The 3H-JA was observed in phloem and xylem at the young stems where 3H-JA was applied and its adjacent positions. The results suggested that JA could be transported rapidly from phloem to xylem through cambium and transported upwards as well as downwards through vessel tube and sieve tube. Immunofluorescence localization showed that exogenous JA was distributed mainly in the phloem during 30 minutes to 1 day after JA application.

The results were testified with works made by other researchers using radioisotope technique. However, our techniques can mark the idiographic location of JA in the rubber tree, but radioisotope technique does not. The techniques of autoradiography in paraffin section and indirect immunofluorescence localization provided feasible approaches for studying the transportation of JA in the rubber tree and further afforded reference for investigating the physiological function of JA in the rubber tree.


Keywords: Hevea brasiliensis, jasmonic acid, 3H-JA, autoradiography, EDC (1-Ethyl-3-(3-dimethyl aminopropyl)-carbodiimide hydrochloide), indirect immunofluorescence localization




Huang Yanggang, Chen Qiubo, Luo Wei and Lin Zhaomo

South China University of Tropical Agriculture; Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences

Danzhou, Hainan 571737, China





Drought stress is a big problem in China’s rubber plantations. Growth of both mature and immature trees was stunted by drought. Severe yield loss due to prolonged drought in the last two years has marginalized rubber plantation benefits although rubber price was extremely high. Studies on measures and mechanisms of improved drought tolerance of rubber trees are significant in both knowledge and technical innovation for the benefit of the rubber sector. Observations on response of young rubber buddings under drought stress or normal moisture conditions were made in controlled environment. Soil moisture status has been related with photosynthesis, transpiration, canopy development, root system development, biomass production and latex vessels development. Optimal and minimum water supply to young rubber buddings has been explored for normal growth. Some recommendations are made on the basis of the experimental results.


Keywords: Rubber tree, young buddings, drought stress, drought tolerant, water deficiency, soil moisture, water potential.




Pisamai Chantuma1               Phillipe  Thaler2                     Eric  Gohet2

Sornprach  Thanisawanyangkura3       Poonpipope  Kasemsap3


1 Chachoengsao Rubber Research Center , Sanam ChaiKhet District, Chachoengsao 24160, Thailand.

2 Doras Center, Kasetsart University, Bangkok 10900, Thailand.

3 Kasetsart  University, Bangkok 10900, Thailand.





Starch and TSS (total soluble sugar) status in rubber tree was investigated to assess carbohydrate reserve related to tapping system. RRIM 600 clone were studied for three years in Chachoengsao Rubber Research Center (CRRC-RRIT-DOA). Trees were tapped using 1/2S d/2 (control), 1/2S d/3.ET 2.5%,8/y and the DCA system (double-cut alternative tapping system). Bark and wood tissue were collected in October 2002 (period of high rainfall and high latex production) at various positions along trunks and were analyzed using starch enzymatic analysis technique. Together with a higher production of latex, DCA system had higher content in both starch and SS in wood. In bark, SS was also higher in DCA, whereas starch was not different among treatments.  Despite an overall decreasing bottom-up gradient in starch content in wood, distribution patterns were affected by the position of tapping cuts. There was often a decrease in starch content in both wood and bark within the bark regeneration area, i.e. the area which have been already tapped.


Keywords : Hevea brasiliensis, latex, sucrose content, metabolic activity, carbohydrate, tapping systems,




Krissada Sangsing1, Xavier Le Roux2, Poonpipope Kasemsap3 and Sornprach Thanisawanyangkura4

1Surat Thani Rubber Research Center, Office of Agricultural Research and Development Region 7, Department of Agriculture, Bangkok 10900, Thailand. 2UMR Ecologie Microbienne des Sols (CNRS-University Lyon1), bat. 741,43 boulevard du 11 November 1918, 69622 Villeurbanne, France. 3Department of Horticulture, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand. 4Department of Botany, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand





The biochemically based model of leaf photosynthesis and stomatal conductance model, the versions that modified by Le Roux, (1999) were used to parameterize and to test for rubber. The key parameters of the photosynthesis model were determined from the response of photosynthesis to CO2 concentration and leaf irradiance. While, the key parameters of the stomatal conductance model were determined from the stomatal conductance response to leaf irradiance (Q), leaf temperature (Tl), water vapor pressure deficit at the leaf surface (D) and air CO2 concentration at the leaf surface (Cs). The three key parameters of the photosynthesis model (maximum carboxylation rate Vcmax, maximum electron transport capacity Jmax and dark respiration rate Rd) and the key parameter of the stomatal conductance model (reference stomatal conductance, gsref) were linearly correlated with the amount of leaf nitrogen per unit leaf area (Na). This relationship could be used to describe nitrogen effects on these parameters for leaf from both rubber clones (RRIM 600 and RRIT 251). Nitrogen use efficiency expressed as Vcmax/Na and Jmax/Na of RRIM 600 were significantly greater than those of RRIT 251. Influence of leaf temperature on photosynthetic capacity was observed. At a given temperature, an increasing of Vcmax of RRIM 600 was greater than that of RRIT 251. Strong correlations were found between stomatal conductance (gs) and Q, D, Tl and Cs. To test the model parameters, measurements were made on varies leaf age for both clones. Despite a large variance between measured and simulated in stomatal conductance values, an increasing of simulated values with increase of measured values were observed. The model predicted photosynthesis exhibited well at leaf scale for both clones. The results indicate that the photosynthesis-stomatal conductance model developed here could be applied to rubber tree both at branch scale and canopy scale.


Keywords: Photosynthesis, stomatal conductance, maximum carboxylation rate, maximum electron transport capacity, dark respiration rate, nitrogen, rubber tree, Hevea.




Philipose Omman and Reghu C.P.

Rubber Research Institute of India

Rubber Board, Kottayam-9, Kerala, India





Hevea brasiliensis, the perennial tree species, belonging to the family Euphorbiaceae is the major source of Natural Rubber.  Latex is harvested from the bark through the process of controlled wounding called tapping at specific angles based on the orientation and inclination pattern of laticiferous system.

A detailed investigation on the inclination of laticifers in ten clones of Hevea brasiliensis with special emphasis on the interrelationship and influence of various bark structural characters on the alignment and orientation of laticifers and other phloic elements was made.  The clones selected includes Tjir 1, Gl 1, PB 86, GT 1, PB 28/59, RRII 105, RRIM 600, RRIM 703, PB 235 and RRII 300 at an age of  17-21 years.  Seedling progenies of two Wickham x Amazon cross combinations (RRII 105 x MT 1005; RRIM 600 x AC 495) and bud grafted plants of RRII 105 and RRIM 600 were also studied at the age of 4 years to understand the inclination pattern of laticifers in the immature growth phase.

The present study revealed that there was clonal variation in the direction of inclination of latex vessels.   In six clones viz. RRIM 703, Gl 1, RRII 300, Tjir 1, PB 235 and GT 1 the laticifers and phloic rays were inclined towards the right whereas in PB 86 the inclination was towards the left.  In three clones viz. RRII 105, PB 28/59 and RRIM 600 the laticifers were inclined towards both directions.  In the immature phase, the seedling progenies of the cross combinations showed rightward inclination of laticifers and phloic rays.  The young budded plants of RRII 105 showed rightward inclination whereas those  of RRIM 600 showed both right and left ward inclination.   About 90 % of the laticifers  were  distributed contiguous to phloic rays. Regression analysis indicated that various independent variables were positively and negatively associated with the dependent variable, laticifer inclination.  In general, the inclination of phloic rays has been identified as the most influential positive factor on laticifer  inclination.  The significance of orientation and inclination of latex vessels on direction and angle of tapping cut in the context of realization of potential yield of different clones is discussed.


Key words: Hevea brasiliensis, laticifer inclination, bark anatomy





Ha Van Khuong, Technical department - Viet Nam General Rubber Corporation

236 Nam Ky Khoi Nghia, District 3, Ho Chi Minh city, Vietnam.


Physiological criteria for evaluating production of newly evolved hybrid clones


N. Usha Nair and Kavitha K. Mydin

Rubber Research Institute of India, Kottayam – 686009, Kerala, India.




                Latex clonal typology a Physiological criteria relating the levels of four physiological parameters in latex (sucrose, thiols, inorganic phosphorus and dry rubber content) with the production metabolism of clones has been used to evaluate the production potential of nine hybrid clones of RRII 40 series of parentage RRII 105  RRIC 100.  The physiological parameters studied include LD parameters viz; sucrose, thiols, inorganic phosphorus and drc and annual mean dry rubber yield (g/t/t) in the fifth year of tapping.  Among the clones with promising yield RRII 414, 417, 429, 422 and 430 have shown an yield improvement of 26-35 % over the parent clones RRII 105.  The superior yield performance of RRII 400 series over RRII 105 is explained in relation to certain stable physiological characteristics exhibited by the new clones.  The yield potential, response to different exploitation systems and susceptibility to tapping panel dryness (TPD) of RRII 400 series clones is assessed based on the concentration of sucrose, inorganic phosphorus and thiols relative to the parent clones RRII 105.  




Ugwa I. K., Orimoloye* J. R. and Kamalu O. J.

Rubber Research Institute of Nigeria (RRIN)

P.M.B. 1049, Benin City, Nigeria

* Correspondence: E-Mail




The morphology, physical and chemical properties of three pedons on the coastal plains sands of Southeastern Nigeria were studied and evaluated. The soils were generally well drained deep and sandy. Soil reaction is acidic (pH 4.5 – 5.2) while ECEC was very low to medium. The soils have Udic moisture regime, argillic to cambic subsurface horizons and were classified as Tropoudult and Dystropept (USDA soil Taxonomy) or Dystric Nitrosol and Gleyic Cambisol (FAO/UNESCO legend). A parametric approach was employed in rating the suitability of the soils for Hevea and was found to range from highly suitable (S1) to marginally suitable (S3). The soils have good physical conditions for Hevea cultivation but the fertility status of the soils suggests a good fertilizer management for sustained Hevea productivity.


Key words: Land Suitability, Hevea brasiliensis, Acid sands, Nigeria




1Idoko, S. O., *1Orimoloye, J. R. 2Uzu,F.O., , 1Omorusi, V. I. and Ugwa, I. K1.

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

2. University Of Benin, Benin City.

* Corresponding Author, E Mail:




A field experiment was carried out at the Rubber Research institute of Nigeria (RRIN) during the 2001 and 2002 cropping seasons to evaluate the viability of intercropping cocoyam with matured rubber plantation and to quantify the effects of Rock phosphate application and indigenous mychorrhizal fungi on the yield of cocoyam and rubber latex. The results indicated that intercropping with matured rubber reduces the edible cormel yield of cocoyam by 27, 23, and 65% in the 0, 60 and 120kg P ha-1 treatments respectively. It also delayed the leaf shedding of cocoyam by about 9 weeks. However, the latex yield of rubber was not significantly affected by cocoyam intercropping. Land Equivalent Ratio (LER) values of 1.31, 1.60 and 1.68 were obtained from 0, 60 and 120 kg P ha-1 treatments respectively in the rubber/cocoyam intercrops indicating higher land use efficiency in intercropping cocoyam with matured rubber than planting cocoyam or rubber as sole crop. Vesicular Arbuscular Mychorrhizal (VAM) spore counts and root colonization were found to be higher in treatments receiving less P fertilization. It was suspected that the VAM activities could have accounted for bringing the cocoyam yield of treatments with no P application at par with those receiving P fertilizers in addition to other factors affecting the availability and utilization of P in acid soils. The higher land use efficiency and the possibility of securing subsistence through arable cropping while simultaneously gaining cash income through rubber latex would make cocoyam intercropping with matured rubber attractive to smallholder farmers and ultimately increase the rubber plantation establishment in Nigeria.






R S Dharmakeerthi, R Ranasinghe, S N Silva, A Yakandawala and C K Maheepala

Rubber Research Institute of Sri Lanka

Dartonfield, Agalawatta, Sri Lanka




Nutrient requirement of new, high yielding, vigorously growing Hevea clones could be different from that in traditional clones.  Changes in nutrient requirement should be reflected in girth of the tree and these changes may be used effectively in a site-specific fertilizer recommendation program. Therefore girth response to fertilizers of some new Hevea clones was determined in a red yellow podzolic soil in Sri Lanka. Five clones viz RRIC 110, RRIC 121, RRISL 203, RRIM 712 and PB 260 were given 0, 0.5, 1, 1.5 times the currently recommended fertilizer mixture in one experiment. In another experiment, three clones viz. RRISL 201, RRISL 202 and BPM 24 was received 0.6, 1.4 and 2.2 times the currently recommended P, K and Mg levels. Girth and girth increment of the tress was measured during the immature period. Stepwise regression analysis showed that the girth increment during a given year is dependant on the initial girth of the plant, fertilizer level and the clone. Importantly, it was also observed that the girth response to fertilizer is dependant on the initial girth of the plant and clone. These effects were quantified using regression models.






D.V.K. Nageswara Rao

Rubber Research Institute of India, Kottayam – 686 009, Kerala, India





Jenny’s equation of soil formation showed the invariably important role of topography in soil formation and development.  Rubber growing soils in the traditional region in India represents rugged terrain containing hills and valleys. DEM (Digital Elevation Model) provides a cheap and reliable way of predicting land properties, which have strong correlations with attributes derived from elevation data.  DEM could be used to derive landform attributes important to soil development and distribution and a good way of deriving landform attributes that may be used for soil prediction.


Modern database management tools like remote sensing in conjunction with GPS (global positioning system) greatly helped in locating the rubber plantations in the study area. The DEM with 90 meter resolution, generated during the SRTM (Shuttle Radar Topographic Mission) was used in the present study to visualize terrain for 3D analysis.  Use of GPS in selected fields helped to locate both rubber and soil units, the characteristics of which were already described in the inventory of soil resource maps.  Satellite imagery or soil maps are  2D maps and did not provide the information regarding the elevation, slope and aspect etc.  Use of DEM facilitated to extract these landscape attributes with ease, which could be used to relate to the soil properties so that landscape-soil interrelationships could be assessed.  This information is needed for all operations that are ought to be taken in undulated terrain for soil and water conservation measures and development of fertilizer application strategies in addition to infrastructure development like road construction etc.  The DEMs can be generated either by digitization of topomaps or collected by satellite sensors, with varied resolutions.  DEM collected during SRTM are available via Internet for free.


Phosphorus uptake by rubber (Hevea brasiliensis) – modifications

at the  rhizosphere for improved uptake


Mercykutty Joseph,1 Syamala V.K.1 Krishnakumar  R ,1

Kochuthresiamma Joseph 1and Gunter Neuman2


1.       Rubber Research Institute of India, Kottayam, Kerala, India

2         Institute of  Plant Nutrition, University of Hohenheim, Stutgart, Germany




                Hydroponics and rhizobox experiments were conducted with rubber seedlings to understand the mechanisms of rubber roots for improved uptake of phosphorus(P) from soil.  Root  growth of mature rubber trees grown under two P availability situations were also compared.  Hydroponics and rhizobox experiments indicated that in P deficient plants the root growth was more and the shoot/root ratio was low compared to the P supplied plants.   Similarly, in rhizobox  plants  grown  in low P soil , the root area and root length were high in control plants with no P supply compared to plants which received P either through water insoluble or water soluble form of P fertilizer.   In the high P soil reverse trend was recorded and P supply through water soluble P further improved the root growth compared to control. 

                Acid phosphatase and alkaline phosphatase enzyme activity was found to be high in P supplied plants.   The pH of  the nutrient solution were monitored and was negative. The difference was more pronounced in P deficient condition.

                Root length and root area of mature rubber trees were high under low P availability indicating the specific physical adaptation of increased root growth for increasing the absorbing surface.  Root length and root area were high in the control plants compared to P supplied plants.  The trend was reverse in the high P situation.  AMF infection in the roots of trees grown in the low P and high P soils were  also compared.  Per cent AMF infection was low in both the locations.


Key words: Phosphorus, Rhizosphere, Root growth, Phosphatase enzyme, Rubber (Hevea brasiliensis)




Tong Viet Thinh

Rubber Research Institute of Vietnam




On red basaltic soil in Highlands, from years of 2002-2005, four fertilizer experiments were set up and observed elaborately in order to evaluate affect of inorganic N, P and K on latex yield under two groups of tapping year and finally to find out their optimum combinations for maximum yield.

Through results obtained it was confirmed that K played a role much more important in improving yield than those from K and P. And with application of 80 kg K2O/ha, it made a significant yield increase of more than 10% at some observation months and years.

In the 2nd – 5th tapping years, order second model of response surface gave good fit with confidence of 99% and very good prediction of optimum N, P and K combination.





Elsie S.George, K I.Punnoose, P.Prasannakumari and N.Usha Nair

Rubber Research Institute of India

 Kottayam-9 Kerala, India





Hevea brasiliensis is a tree crop with a life span of more than thirty years. Effective nutrient management in a mature rubber plantation requires an accurate accounting of nutrients removed from soils through latex and the production potential of high yielding clones can be realized only through effective nutrient management. On this basis a more accurate assessment of nutrients removed from potential clones will be useful for providing clone specific fertilizer recommendation.

 A study was conducted at the Rubber Research Institute of India for two years to measure nutrient content and nutrient drainage from some of the promising Hevea clones through latex. Thirteen clones of 13 year old were selected for the study. Latex samples of middle 5 trees in each clone under normal tapping were pooled together to form a composite sample and replicated 4 times. Latex samples were collected on bimonthly basis for two years and analyzed for N, P, K, Mg, Fe, Mn, Cu and Zn. Also collected monthly yield and calculated the actual drainage of nutrients from different clones through latex.

Significant clonal difference in latex nutrient content was observed for N,P, K and Mg. Among the micronutrients significant difference was observed only for Zn and Cu. The clonal differences in nutrient removal through latex were significant through the analysis of variance test. The removal of N, P, K and Mg from different clones through latex vary from 6.37 to 19.14; 2.72 to 8.65; 6.30 to 18.82 kg and 2.57 to 7.69kgs per hectare per year respectively. Similarly removal of Fe, Mn, Zn and Cu from different clones vary from 39.00 to 88.02g; 1.20 to 2.39g; 5.72 to 20.11g and 5.63 to 18.50g per hectare per year respectively .It was also noted that the actual removal of N, P, K and Mg from high yielding clones is well above the values reported earlier. Also the micronutrients in latex and its removal through latex exhibited more clonal variation than macronutrients.

Hence the depletion of soil nutrient reserves and consequent fertilizer requirements can vary considerably depending on the clones This information could be used in conjunction with nutrient management planning and for providing clone specific fertilizer recommendations.


Key words: Hevea brasiliensis, Clones, Latex nutrient concentration, Nutrient  drainage.




S. Mak and S. Yin

Cambodian Rubber Research Institute (CRRI)

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


A. Pookpakdi

Kasetsart University

Chatuchak, Bangkok 10900, Thailand




The experiment on the yield and quality of rubber as affected by irrigation and fertilizer applications is an on-farm research conducted at the Rubber Plantation of Sindane Thai Rubber Co., Ltd. The objective of the experiment was to investigate the yield and quality of rubber as affected by irrigation and fertilizer and whether this practice might or might not be increasing the economic return to the farmers. Experimental design used was a split plot with three replications, having irrigation and non irrigation as main plots and three formulas of NPK fertilizer of 15-7-18, 30-5-18 and 23-5-18 as subplots factorially arranged within each main plot. The trial was conducted on the clay loam soil of Klongluk series having the pH of 5.0 with 1.6% organic matter, 103.3 and 133 ppm of P and K respectively. The result of the experiment revealed that irrigation treatment increased the yield per tree per tapping, monthly production and also total rubber production per year. Under non-irrigation, the percentage of dry rubber content (DRC) was higher than those of irrigation treatment. Result of latex diagnosis analysis showed that sucrose and total solid content (TSC) of samples were not affected by irrigation and fertilizer treatments. Inorganic phosphate (Pi) increased in the irrigated plot than those of non-irrigation but was not significantly differed (P>0.05) among others. Thiol content in latex samples taken from the irrigated plot was significantly (P<0.05) higher than non irrigated plot. Girth of rubber increased as the result of irrigation application. The result of this study did not show the effect of fertilizer treatments in any of the parameters measured. It may be possible that it would take a longer time than the experimental period before the effect of fertilizer will be pronounced.


Keywords: Hevea brasiliensis, dry rubber content, latex diagnosis.




S. K. Dey and T. K. Pal

Rubber Research Institute of India

Agartala 799 006





A density trial with combination of different dose of fertilizer was conducted with two popular clones viz. RRII 105 and RRII 118 at the Regional Research Station, Agartala with an objective to maximize the rubber yield per unit area of land. The density adopted were 420, 606 and 824 trees per hectare. Results showed that high growth of plant in low density and high yield per tree, but relatively low yield per hectare. The percentage of tappable trees was low due to poorer tree girth in high density during initial years. However, the number of tappable trees was higher which had resulted high yield per hectare. Percentage of wind damage was also low in high density. Response to high dose of fertilizer was not evident. Maintaining a tree density of 606/ha was appears to be reasonable. Reasonable number of tappable trees could be available in subsequent years in spite of loss of trees due to wind damage.


Key words : Hevea brasiliensis, Planting density, Growth, Yield


First results from an experiment

on on-farm planting material production in Cameroon


Bénédicte Chambon1, Pierre-André Owona Ndongo2, Samuel Monono2, Simon Gobina2 and

 Jean-Marie Eschbach1


1 CIRAD – Performance of tree crop based system

2 IRAD – National Rubber Research Programme





Rubber smallholdings have yet to be widely developed in Cameroon and, in the absence of a support programme for that sector, small and medium-sized farms are encountering numerous difficulties. One of their major constraints is access to budded planting material, resulting in a substantial use of seedlings to develop self-funded plantations.


Yet, the use of budded planting material is a strong determinant in the future productivity of a plantation, and consequently in farmer incomes.


Based on experience in Southeast Asia, we put forward the hypothesis that Cameroonian smallholders could produce their own planting material. Developing budded plant production on farms would be well adapted to their socio-economic conditions.

An on-farm experiment was set up in two villages of South-West province in Cameroon to test that hypothesis. This paper sets out briefly to describe the methodology used, before going on to present the first results obtained. They indicated that the cost of budded material produced by farmers was generally well below the agroindustrial selling price; most of the farmers sought to reduce their financial investment; planting material production enabled farmers to clearly limit financial costs. However, several difficulties were encountered in the first year of the experiment.   


The conclusion drawn is that, provided farmers receive ample technical supervision, supporting budded planting material production on farms, by using a collective budwood garden, could be a worthwhile alternative for improving the incomes of small and medium sized rubber farms in Cameroon. However, this experiment needs to be replicated on a larger scale to confirm the preliminary results.


Comparative clonal studies in CAMBODIAN RRI

First Results from 4 rubber large scale clonal trials

in cambodia


P. Chetha, H. Bunthuon and C. Chek

Cambodian Rubber Research Institute (CRRI)

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


R. Lacote and A. Clement-Demange


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





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 clonal trials have been set up in CRRI. The study compares 29 clones on the growth and on the yield. The first results from these 4 Large Scale Clonal Trials confirm some other results issued in other countries, such as the good vigour of PB235, PB280, PB330, IRCA111, and IRCA230 in the immature period. By contrast, PB260, PB314 and IRCA109 appear not more vigorous than GT1. The highest yielding clones in this early phase of tapping are IRCA109, IRCA111, IRCA130, IRCA209, IRCA230, K1, PB235, PB314, PB330, RRIC101, and RRIM712. These preliminary results are still insufficient for evaluating these clones in those trials. It must be underlined that the growth of PB217 appears reasonably good for allowing the development of this clone in Cambodia. In this early phase, that PB217 has not showed its high yield potential yet. PB330 or IRCA230 could be considered as the most interesting among the clones studied here for development in smallholdings.


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




Aidi-Daslin, and  Sekar  Woelan,

Indonesian Rubber Research Institute

PO. Box 1415 Medan 20001, North Sumatra, Indonesia




The rubber breeding activities in Indonesia had produced new improved rubber clones. Start 1990, the wide crossing used the parents which have high latex yielding and fast growing were made, mainly to assembled superior clones as latex yielder and timber-latex yielder also. The best genotype of progeny test (seedling evaluation trials) at F1 population were selected and then were named IRR (Indonesian Rubber Research) series clone.  Clones trials had been conducted  in promotion plots (100-200 tree per plot, no replication), preliminary trials (20-50 tree per plot, three or four replication) and adaptation/further trials (400-500 tree per plot, no replication).  Several clones of IRR 100 and 200 series,  namely IRR 104, IRR 112, IRR 118, IRR 211 and IRR 220  showed good latex potency and wood yielder, which suitable to be developed for commercial  planting on smallholders and  rubber estate. Clones IRR 104, IRR 211 and IRR 220 were latex yielder type. These clones have very high latex yielding but moderate wood potency. Clones IRR 112 and IRR 118 were timber-latex yielder type. These clones have high latex and wood potency, and during immature period   showed  fast  growing, so that ready for tapping less than four years. Latex yield, growth and  other secondary characteristics above clones will be presented in this paper.


Keywords: Rubber clones, latex yield, wood potency





Rasamee  Suravanit1     Krissada  Sangsing2     Wittaya  Prommee2

Wiparat  Damrikhemtrakul3     Wanpen  Prukwiwat4     Arom  Rodesujit2     Verapong  Tan-apirom4 

1 Rubber Research Institute of Thailand :

2   Suratthani Rubber Research Centre

3   Information Technology Center, Department of Agriculture

4   Phuket Technical and Production Resources Service Center





Preliminary Proof Clone Trial of Ortet Clones from Brazil is the Small Scale Clone Trial on Brazilian ortet clones which had been collected from Brazil by IRRDB in 1981, to select the high yielding clones with good secondary characteristics as germplasm data base for further rubber breeding programme.  The experiment was conducted in 1988 at Phuket Technical and Production Resources Service Center, Phuket Province, Thailand.  Ninety-six Brazilian ortet clones, RRIC 121, BPM 24, GT 1 and RRIM 600 were compared in Simple Lattice Design with 2 replications.  It showed significantly in girth and latex productivity, many Brazilian clones were very poor in girth, started tapping when the trees were 8 years old with only 64 clones.  Most of Brazilian clones showed low latex productivity. Only MT/I/2 15 was the one latex producer Brazilian clone in this experiment.  The best three high yielding clones were RRIC 121, RRIM 600 and MT/I/2 15.  When the trees were 17 years old, there were 20 Brazilian clones showed better girth than standard control RRIM 600 (76.63 cm.). The selected fast growing clones in the pre-tapping and under tapping phase were CNSAM 7701 (102.14 cm, 4.56 cm/year), RO/I/63 86 (94.23 cm, 3.85 cm/year) and RO/I/24 61 (91.56 cm, 3.94 cm/year).  Most clones susceptible to Phytophthora leaf fall.


Keywords: Rubber, Preliminary Proof Clone Trial, Ortet Clones, Brazilian clone




P.M. Priyadarshan 1, G.C. Mandal 2, M. J. Reju 3, D. Mondal 1, R.P.Singh3,

S.K. Dey 1D. Chaudhuri 2, A. P. Thapliyal 3, Gitali Das 4, R.S. Singh 4 ,Krishna Das1, Rajeswari, M.J. 5 and Y. A. Varghese 5.

1 Rubber Research Institute of India, Regional Station, Agartala – 799 006, Tripura,

2 Rubber Research Institute of India, Regional Station, Guwahati, Assam

3 Rubber Research Institute of India, Regional Station, Tura, Meghalaya

4 Rubber Research Institute of India, Regional Station, Nagrakatta, West Bengal.

5 Rubber Research Institute of India, Kottayam.




Clone evaluations for north-east India commenced towards the end of 1970’s. These areas offer multitude of stresses like low temperature, wind, high altitude and infestation Oidium heveae. The breeding programmes for these areas are streamlined as evaluation of clones, recombination breeding, evaluation poly cross progenies and evaluation of genetic diversity. PB 235, RRIM 600, RRII 203, RRII 208, RRIM 703, RRII 118 and Haiken 1 are adjudged as high yielding in Tripura. Comparison of same clones in Assam and Meghalaya (low and high altitudes respectively) proved differential performance. Preliminary results showed while RRIM 600, RRII 105 and PB 235 exhibited higher yield in Assam, RRIM 600, RRII 118 and RRII 105 proved to be potential clones in Meghalaya. These results amply prove the necessity of deriving clones with specific adaptation to such areas. Recombination breeding in Tripura involving both Wickham and Amazonian accessions yielded 52 + 642 hybrids in two sets. The poly cross progeny evaluation in Tripura resulted in ten selections that are with high yield and desirable secondary attributes like resistance to Oidium infestation and wind. Yields of polyclonal seedlings and multi clonal populations are on par. North-east India contributes only about 2.7% of the total production, calling for urgent measures to enhance productivity through recommending environment specific clones.


Key words: Hevea, clone, stress factors, non-traditional areas, yield, recombination breeding, specific adaptation,





Mercykutty, V.C., Nazeer, M.A., Varghese, Y.A., Meenakumari, T.

and Saraswathyamma, C.K.

Rubber Research Institute of India, Kottayam – 686 009.




                Systematic screening of a large population of seedling mother trees was carried out at Cheruvally estate of Harrison Malayalam Limited in Central Kerala for selection of high yielding mother threes. Forty two ortets were finally selected based on yield, girth and bark parameters. These were cloned and evaluated in a small scale trial. Clonal performance was evaluated for yield and other secondary attributes during the first five years under tapping. The parameters evaluated include yield, girth and timber attributes. Significant clonal variation for all the traits was noted, which resulted in selection of eight promising primary clones. The clones designated from the estate from which they were evolved include Cy O 18, Cy O 30, Cy O 31, Cy O 35, Cy O 41, Cy O 43, Cy O 48 and Cy O 72. With respect to GI on tapping, the highest annual girth increment on tapping was recorded by the clone Cy O 31 (5.36 cm) followed by Cy O 48 (4.27 cm) and Cy O 35 (4.12 cm) which was significantly superior to RRIM 600,  a clone which is noted for high girth increment during tapping.       Cy O 31, Cy O 43 and Cy O 48 were three ortets noted for high yield and high girth increment rate on tapping. Moreover, the high yielding capacity of  these three clones combining high bole volume make them potential candidate clones for exploitation as latex timber (LT) clones in the future large scale evaluation and release of new clones. Three top ranking clones viz. Cy O 48, Cy O 41 and Cy O 35 recorded a mean yield of 67.67g/t/t, 64.33g/t/t and 60.37 g/t/t respectively and they were significantly superior in yield to that of RRII 105 with above average bole volume. Among these, Cy O 48 was the most promising selection in terms of yield, vigour and bole volume. The superiority of ortets with respect to yield and secondary characters is discussed in detail, giving emphasis to the eight final selections based on yield.


Key words: ortet selection, primary clones, Hevea brasiliensis, bole volume,

 immaturity period.




Y. Annamma Varghese,  Kavitha K. Mydin and Alice John

The Rubber Research Institute of India, Kottayam 68 6009, Kerala, India


Genetic improvement programmes has paid rich dividends in increasing yield by several fold  from a low productivity of around 300 kg ha -1 yr -1 for ordinary seeds to around 3000   kg ha -1 yr - 1    for recent hybrid clones. In India so far, 127 Wickham clones evolved in countries like Malaysia, Indonesia, Sri Lanka, Thailand, China and Ivory Coast constitute the exotic component of the gene pool. Utilizing this genetic base substantial improvement in productivity has been achieved over the years. The high productivity now achieved by India can be attributed to the high yielding hybrid clones of which the most popular clone is RRII 105 with a production potential of over 2000 kg/ha/year in farmers plots. Over 100 potential clones evolved by hybridization, ortet selection and polycross breeding are under various stages of evaluation.           

The current series of hybrid clones developed by the RRII viz. RRII 400 series is another remarkable achievement. Five of these clone viz.  RRII 414, RRII 417, RRII 422, RRII 429 and RRII 430 with an experimental yield of more than 20 per cent improvement in yield and growth over the high yielding clone RRII 105   have been   included in the planting recommendation of the Rubber Board. Out of a total of 46 clones included in three categories in the current planting recommendation, 15 are Indian clones, while the remaining 31 are of exotic origin from Malaysia, Indonesia, Sri Lanka, China, Thailand and Ivory Coast. Recognizing the potential danger of monoculture of one    or a few high yielding clones in a geographical area, a strategy for encouraging multiclone planting has been recommended by the Rubber Board of India.

Concerted efforts in selecting location specific clones for non-traditional rubber growing areas under sub optimal conditions have resulted in identification of clones for different non-traditional areas. Based on the performance of clones in the regional research stations in the North Eastern states, an ad hoc recommendation of clones has been made.

Realizing the need for broadening the original narrow genetic base, steps were taken for introduction of wild germplasm in to the Indian breeding pool.   Currently, a total of 4548 accessions including 90 ortet clones received from the Malaysian center, have been established for conservation and characterization, evaluation and utilization being done in a phased manner.  Attempts towards establishment of a core collection from the large collection of wild Germplasm has been initiated and established   the first core set of 27 from a set of 81 wild accessions.

In the context of rubber cultivation having been extended to non traditional and marginal areas, screening   wild accessions for   resistance to major diseases, drought and cold conditions is in progress and certain potential accessions were selected for incorporation in to the breeding pool.  Selections with relatively high yield potential in preliminary screening have been subjected to field evaluation. Hybrid progenies from selected parent clones of Wickham and wild Germplasm are also under field evaluation.

Molecular studies in Hevea indicated the potential of DNA based markers for various applications in genetic improvement like assay of genetic diversity and genetic analysis. The significance of crop improvement programmes to meet the current objectives and future demand of the industry are discussed.

Key words:     Genetic improvement, Hevea brasiliensis, natural rubber, wild germplasm, breeding methods



Radha Lakshmanan*, Vinoth Thomas+, C.K.Saraswathyamma, Thomson, T. Edathil, M.R.Sethuraj and K.C. Aipe**

*Regional Research Station, Rubber Research Institute of India, Padiyoor- 670 703, Kerala, India.

Rubber Research Institute of India, Kottayam- 686 009, Kerala, India.

**Associate Professor, Regional Station,  Kerala Agricultural University,  Ambalavayal, P.O., Wyanad, Kerala, India.

+for correspondence




Recognizing the need for identifying clones suitable for high elevations in Kerala, India, an experiment was initiated for evaluating certain popular Hevea clones and ortets identified from high altitude location at Panamaram and Iritty.       

The experiment was laid out at the Regional Research Station of the Kerala Agricultural University at Ambalavayal (latitude of 11o 37’ N, longitude of 76o 12’  E and at an altitude of 974 m MSL). Ten  ortets identified from the high altitude area viz., P 1, P 2, P 90, P 121, P 155, P 213, P 270, P 280, P 296, Iritty 1 and five popular clones viz., RRII 105, RRII 203, RRIC 100, RRIC 102 and PB 86 were laid out employing a Randomized Block Design during 1995. Eight years after planting, observations such as girth at 150 cm from the ground, incidence of powdery mildew leaf disease, bark anatomical parameters related to yield and latex yield by test tapping were recorded.

Among the clones selected, P 1 recorded the highest girth (39.7cm) followed by P 270, Iritty 1.  P 2 recorded the lowest girth of 29.6 cm. Significant clonal variation was observed for number of latex vessel rows while the differences for bark thickness was  not significant.   PB 86 recorded the highest test tap yield (11.4 g/t/t) and was on par with P 270, RRIC 100, Iritty 1, RRIC 102 and RRII 105. Iritty 1 showed the highest degree of disease tolerance to powdery mildew followed by P 90, P 270  while clones such as RRII 105 and RRII 203 were highly susceptible to this disease. However, P 280, P 213,  P 1 and RRIC 100, RRIC 102 and PB 86 showed good disease control after treatment. Out of the fifteen clones evaluated,    Iritty 1 performed better in the high altitude station of Wyanad in terms of girth, number of  latex vessel rows, yield and tolerance to disease followed by PB 86, RRIC 100 and RRIC 102. The potential of these clones for cultivation in the high altitude locations is discussed.





Lai Van Lam , Le Mau Tuy, Tran Thi Thuy Hoa (*) and Le Hoang Ngoc Anh

Rubber Research Institute of Vietnam

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

(*) Vietnam Rubber Association





The presentation would provide general insight into the genetic and agronomic potentials of the IRRDB’81 Hevea germplasm to serve as guidelines in planning the breeding program for further improvements. The estimate was conducted on progenies derived from the IRRDB’81 in early selection trials for RRIV’s hand pollination programs from 1997 to 2005. Genetic variances and narrow sense heritabilities of yield and girth were estimated for full siblings using mating design North Carolina Model II (N.C.M.II) of Comstock and Robinson (1952). Other genetic parameters such as selection gains, heterosis, fruit sets and agronomic performances for main characters of the germplasm progenies are also discussed.

The IRRDB’81 Hevea germplasm has evidently broadened the pool of genetic materials for the long term breeding program in the RRIV. The findings, although limited, of a largely additive genetic inheritance, initial indication of heterosis and rather good response to selection for latex productivity and growth of the germplasm progenies at the early stage could provide some clues into the approach of acceleration of genetic improvement and more effective utilization of the new germplasm in Hevea  breeding program. 


Keywords: IRRDB’81 Hevea germplasm, genetic variation, heritability, genetic gain, heterosis  




Le Mau Tuy*, Vu Van Truong*, Le Dinh Vinh* and Tran Thi Thuy Hoa**

*: RRIV- 177 Hai Ba Trung, District 3, Ho Chi Minh city, VN

**: VRA- 236 Nam Ky Khoi Nghia, District 3, Ho Chi Minh city, VN





Clones derived from RRIV’s hand pollination campaigns of 1987 – 1990 and some introduced clones were planted in  two Small Scale Clone Trials. Elite clones that showed high yield and vigorous after 5 – 7 years of tapping were selected. All these clones were bred in RRIV and the best clone, LH 90/952 was having very high yield and good in secondary characters. Besides, the latex physiological parameters, wood volume of selected clones were presented and promising clones as parents were discussed.


Keywords: Rubber breeding, clone, RRIV (Rubber Research Institute of Vietnam).




K. O. Omokhafe*, F. A. Akpobome, I. Nasiru

Rubber Research Institute of Nigeria,

P. M. B. 1049, Benin City, Nigeria.




The breeding population of rubber has concentrated on the 1876 Wickham collection of Hevea brasiliensis. Appreciable progress in yield improvement was achieved but such improvement has reached a plateau. Despite the germpasm collection of the IRRDB in 1981, there is no significant improvement in latex yield. Rubber farmers have challenged Plant Breeders to provide the dwarf H. brasiliensis to check wind damage and ensure more efficient and less expensive control of leaf diseases. These factors are serious limitations to cultivation of rubber. This paper highlights the procedure to overcome this problem and enhance selection progress through germplasm exploration, conservation and use.

Analysing the genetic response to environmental stress in young rubber plants (Hevea brasiliensis)

for predicting adult phenotypic expression


Pascal Montoro, André Clément-Demange

CIRAD, Tree Crops Department, Montpellier, France




Genetic improvement of Hevea brasiliensis is a long process given both the immature period before latex production, the choice of parents for recombination and a three stage clone selection scheme covering 20 years or more. There are frequent contentions that genomics and biotechnologies will reduce drastically this duration. On the contrary, breeders can argue that phenotypic studies at field level, based on the observation of the global expression of the genotypes on rather mature trees (5 to10 years of age), will always be necessary for clone recommendation. In rubber, improving the accuracy of evaluation is probably more efficient than reducing its duration for achieving a better genetic gain and ensuring regular release of new efficient, stable, and diversified clones. Integration of genomics and biotechnology tools can strongly contribute to very early screenings for a quick enrichment of the breeding populations with the most favourable alleles, or to improve cultivated clones by genetic modification. However, genetic recombination or genetic insertion into the genome respectively upon meiosis and transgenesis strongly modify genetic and epigenetic interactions. These changes impact both on plant metabolism and development. Gene expression analyses cannot be successfully applied directly to breeding. They must be validated on young plants, under different stress treatments (notably wounding and ethylene applications), and in controlled conditions (greenhouse). With this view, a range of gene expression analyses based on RT-PCR, macro-arrays, etc. was initiated on mature budded plants, on juvenile plants issued from in-vitro, as well as on transgenic plant material for characterizing early response to stress of contrasted clones (PB 260, PB 217, RRIM 600). Avaibility of young grafted plants and capability to apply on them a set of experimental stress treatments in controlled condition are necessary conditions to study in details molecular mechanisms. This better understanding of plant metabolism can lead to conceptual functioning model for identifying the key genes involved in the response of plants to the exploitation stress (tapping and stimulation) or other biotic and abiotic stresses. Describing a gene ontology might allow to select the key markers/genes responding in the same manner at various stages of development. From the results of that research will be drawn a reduced set of assumptions that can then be submitted to validation on mature rubber trees. This approach is discussed in relation to rubber tree genetic improvement.


Genetic transformation of Hevea brasiliensis by using a non-destructive visual marker (GFP)


Leclercq J., Martin F. and Montoro P

CIRAD, Tree Crops Department, Montpellier, France




With the successful plant of Botany 77(8): 1168-1177) an Agrobacterium tumefaciens-mediated genetic transformation has been developed (Blanc et al., 2006, PCR 24(12) 724-733) and has led to genetically transformed plant expressing the gusA reporter gene driven either by the CAMV 35S or the Hev2.1 promoters.

A way to improve this procedure was to use a non-destructive visual reporter gene, the Green Fluorescent Protein (GFP). Then, a binary vector has been constructed containing the two reporter genes driven by the CAMV 35S promoter. The first results showed that the green fluorescence was strongly visible in H. brasiliensis calli and that earlier selection of transgenic calli was thus possible from the first sub-culture. Comparison of the GUS and GFP activities revealed that the two markers can be used to evaluate transformation efficiency. Using GFP visual marker, transgenic fluorescent calli were selected earlier than transgenic calli using the GUS staining.

GFP visual marker consequently can be used as a selection marker, which could avoid the use of gene conferring antibiotic resistance and shorten drastically the duration of the establishment of the transgenic callus lines. This transformation system is being used for over-expressing genes of interest such those involved in stress tolerance


cDNA-AFLP analysis reveals differential gene expression in  BPM 24 clone of Hevea brasiliensis exhibiting tapping panel dryness (TPD)


Chatchamon Daengkanit *, Sanlaya Chanui **, Pluang Suwanmanee **, Nualpun Sirinupong**

                 * Rubber Research Institute of Thailand, Tha Chana,district,  84170 Surat Thani, Thailand

                  ** Thaksin University,  90000 Songkhla, Thailand





Tapping panel dryness (TPD) is a major factor affecting the productivity of natural rubber throughout the world.  To date, the molecular basis of TPD in rubber tree has not been clear.  In this study, rubber latex from BPM 24 clone exhibiting TPD was characterized for gene expression patterns by using cDNA-amplified fragment length polymorphism (cDNA-AFLP), an extremely efficient method for isolation of differentially expressed genes. In comparison with healthy tree, twenty cDNA-AFLP primer-pairs produced a total of differential 437 cDNA-AFLP fragments on silver-stained polyacrylamide gel, which 148 fragments were polymorphic. These polymorphic fragments revealed differential expressed transcripts based on their presence (53) and absence (39), or difference in the levels of expression, low (25) and high (31) intensity.  All of them are cloning and sequencing to verify their specific expression related to TPD.


Keywords: Hevea brasiliensis, tapping panel dryness (TPD), cDNA-AFLP, gene expression




Vu Van Truong, Lai Van Lam and Le Mau Tuy 

Rubber Research Institute of Vietnam





Wood volume of the IRRDB’81 Hevea germplasm genotypes at the age of 19 – 20 years old in small scale trials was evaluated directly when trees were cut down for replanting. Various regression models for estimation of wood volume based on diameter at 1m from the ground (d) and total height (h) were tested. The total wood volume could be reliably estimated by regression model v = -0.794 + 0.0189*(d*lnh). IRRDB’81 germplasm clones, RO 25/43, RO 20/212, RO 25/45, RO 25/135, RO 25/254, RO 44/268, MT 29/83, AC 42/66 and AC 58/42, showed great potential for wood volume and could be used for timber production and Hevea genetic improvement.





M. J. Rosyid and Heru Suryaningtyas


Sembawa Research Centre

Indonesian Rubber Research Institute

PO. Box 1127 Palembang 30001




In Indonesia the number of wood industries which utilize forest timber as the primer material for their product has recently declined. Some forest timber species such as ramin and shorea have even started to disappear from local and/or national market. These situations have lead to the export of ramin and shorea were banned by the Indonesian government.  As a result, several wood factories utilizing the two forest timber species have stopped their activities; and this has then lead to decrease in foreign exchange and increase in the number of unemployment. In solving the problems it has been explored any timber species which have similar characteristics to that of ramin and shorea; and Hevea rubber timber proved to have that characteristics.  For this reason, rubber timber has therefore nowadays become an alternative to replace forest timber species of ramin and/or shorea.  In line with rubber replanting program in Indonesia, the number of rubber timber factory has also increased; and this has promoted to the development of rubber timber market system, where the marketed products included log timber and sawn timber.  The problem arising in the market system is that the accuracy of timber volume estimation in the field.  The estimate by timber buyers is often inaccurate and this could cause significant economic loss to the buyers.  For this reason, a research to find out the simple, quick and accurate method for estimating timber volume in the field, has been carried out in smallholder rubber and the big estates owned by government and private.  The method was developed by making a correlation between stem girth and timber volume

The research results revealed that the log volume of clonal rubber trees could be calculated using the formula: Vollog = 0.000000908 Sg2.9 m3; where Sg is stem girth, standard deviation of the aggregate (SA) is 0.00 and standard deviation of the mean (SM) is 0.19, the limit of accuracy (SA) = < 1% and of limit accuracy of the mean (SM) = < 10%.  Whereas the volume of swan timber of clonal rubber trees could be estimated using the formula: VolST = 0.0000000271 Sg3.5 m3 ; where SA = 0.02 and SM = 6.05.  The highest deviation was found on the estimation sawn timber for seedling rubber trees, this was due to the growth and the shape of seedling rubber trees were in big variations.  Nevertheless the standard deviation was still low (SA = < 1%), meaning that the formula was still reliable for estimating timber volume in the field.  For the log volume of seedling rubber trees could be estimated using the formula Vollog =    0.000017 Sg 2.04 m3 (SA =0.27 and SM = -102.68).  Whereas the sawn timber volume of seedling rubber trees could be calculated using the formula VolST = 0.0000049 Gd .2.07 m3 (SA = 0.07 and SM = -141.47).


Key words: Rubber, forest, wood factory, rubber wood, volume estimation.


Cocoa: A potential intercrop for mature rubber


                               Sherin George, Sankar Meti and  Usha Nair

                      Rubber research Institute of India, Kottayam-686009, India




Traditional  small holdings are characterized by relatively stable but low yields. Intercropping mature rubber with suitable crops will provide the small farmers with a diversity of enterprise and a degree of stability in income when large price fluctuations occur. A field experiment was conducted in a mature rubber plantation of clone RRII 105 aged 10 years in a small holding representing the central rubber growing tract of India to evaluate the performance of coffee and cocoa as inercrops and  to find out the nutrient requirement of the system. The treatments comprised of two varieties of coffee viz., robusta  and CxR and cocoa inter planted in rubber in combination with two doses of fertilizers viz., 100 and 50 per cent of the recommended dose for coffee and cocoa. Coffee and cocoa were established well and started yielding by third year.  The growth and yield of rubber did not vary significantly among the treatments indicating that intercropping of perennial crops like coffee and cocoa did not adversely affect the performance of rubber.  There was not much variation in the total yield between different varieties of coffee. However, the per plant yield of coffee was only 36 per cent of that under monoculture whereas  the intercrop yield of cocoa was  around 60 per cent of that of monoculture. Though competition existed between the component crops for above ground resources, mainly radiation capture, there was no dearth of below ground resources and the soil fertility was improved under the intercropped situation compared to monoculture rubber. As there was no response to additional fertilizer dose either in terms of growth or yield, the data suggested that the nutrient requirement of the intercropping system was less compared to sole crop and and the fertilizer dose for intercrops could be reduced to half without affecting the soil and leaf nutrient status.

It is evident from present study that cocoa can be  successfully cultivated  as an intercrop in mature rubber. Therefore, the overall productivity and profitability of rubber plantations can be increased with minimal investment by raising cocoa as intercrop.




T.U.Esekhade and M.U.B Mokwunye

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



A seven years (1999 - 2005) study was conducted at the Rubber Research Institute of Nigeria Iyanomo in Southern Nigeria to investigate the effect of selected rubber-based cropping system on the early development of rubber; the effect on the fragile soils and the economic potentials of intercropping rubber saplings.


The study showed that rubber-based cropping systems significantly influenced the development of rubber saplings.  The rubber/cassava system was the most promising in terms of growth development, dry matter production and yield of rubber.  The soils under the rubber-cropping systems showed relative stability in terms of the physical and chemical properties of the soils.


The rubber/cassava system had the highest latex mean yield (2041 kg drc/ha) compared with rubber/natural vegetation (1990 kg drc/ha) and rubber/Peuraria phaseoloides (1958 kg drc/ha) in two years of latex exploitation.


The study also showed that the economic benefit of rubber/cassava system makes it the preferred choice from the selected rubber-based cropping systems, with a net benefit of N1221790 ($8255.3).


Keywords: Rubber-based cropping systems, acid soils, cassava, Peuraria phaseoloides, natural vegetation, economic analysis.



C.K. Jayasinghe




Corynespora leaf fall (CLF) of rubber, a disease with relatively a recent origin has now become a serious threat to the world’s natural rubber industry.  Except republic of China all leading rubber growing countries in the world suffer from this deadly disease.  During its first epidemic in mid 1980’s two prestigious clones, RRIC 103 and RRIM 725 have been wiped out from the major rubber growing countries in South East Asia.  Sri Lanka was the worst affected island and today it enjoys a CLF free new millennium.  The secret behind this success story was the selection of clones through intensive screening during breeding programmes since 1985. Minimising inoculum potential, crown budding and base budding with tolerant clones are the other tools in efficient management of sudden outbreaks and Sri Lankan experience on those aspects are also discussed: However, towards the end of 20th century several outstanding clones in the world namely RRIM 600, RRII 105, AVROS 2037, PB 260, RRIC 110, GT 1 and IAN 873 which have been considered as tolerant genetic material during the first epidemic succumbed to the disease at varying intensities.  The apparent susceptibility of these leading clones which contribute to more than 60% of world’s natural rubber production raises a great concern over the future development of the rubber plantation industry in both African and Asian continents.


Keywords: Hevea brasiliensis, Corynespora leaf fall, clonal resistance, clonal susceptibility




Phan Thành Dũng, Vi Văn Toàn, Trần Ánh Pha, Đàm Văn Chọn

Rubber Research Institute of Vietnam





The first outbreak of brown root disease on rubber trees was recorded on large scale trial. Thousands of trees were affected and killed, practical method of using effective fungicides such as hexaconazole and tridemorph was applied. More than 40.000 rubber trees was treated and  80% to 99% of infected rubber trees cuved that much depended on infection stage.


Key word: Brown root disease, rubber tree, control, hexaconazole, tridemorph.

DISEASES OF RUBBER (Hevea brasiliensis)





Naomi G. Tangonan* and Rodolfol L. Galang**


*University of Southern Mindanao, Kabacan, Cotabato, 9407 Philippines

**Department of Agriculture-Bureau of Agricultural Research, RDMIC Building, Visayas Avenue corner Elliptical Road, Diliman, Quezon City, Philippines 1104





Major rubber growing provinces in Mindanao, Philippines (Agusan Sur, Basilan, Bukidnon, Cotabato, Davao, Sarangani, and Zamboanga del Norte, Zamboanga del Sur,  and Sibugay) were surveyed for incidence and severity of prevailing diseases.

Results of studies showed that there were 20 hosts of Rigidoporus lignosus causing white root rot and 13 of Phytophthora palmivora causing shoot tip blight, black stripe, stem canker, and bark splitting of rubber.

 Twenty rubber clones were screened against different foliar diseases of rubber under nursery condition.