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Item Planting rubber in Eastern province of Sri Lanka: Potential for carbon trading under clean develiopment mechanism(Rubber Research Institute of Sri Lanka, 2010) Iqbal, S.M.M.; Rodrigo, V.H.L.; Munasinghe, E.S.Item Carbon sequestration in mature rubber (Hevea brasiliensis Muell. Arg.) plantations with genotypic comparison(Rubber Research Insitute of Sri Lanka, 2011) Munasinghe, E.S.; Rodrigo, V.H.L.; Karunathilake, P.K.W.Forests play a vital role in regulating the greenhouse gases, particularly the level of atmospheric CO2; hence planting forests has been identified as one of the main options available to mitigate the effects of climate change. Rubber (Hevea brasiliensis), being a multipurpose tree which provides an economically viable (in terms of both latex and timber production) and socially acceptable system, can be effectively used in participatory tree planting programmes. Although the availability of carbon in rubber trees has been assessed before, the potential capacity of sequestering atmospheric CO2 in mature rubber trees has not been quantified. Therefore the present study was geared towards this whilst characterizing the genotypic differences in CO2 sequestration. Two promising genotypes viz. RRIC121 and RRIC100, were selected for the study. CO2 assimilation rates of rubber leaves in three canopy strata under varying light levels were measured and parameters of photosynthetic light response curves (LRC) were estimated. Leaf area distribution and light attenuation within the canopy were also measured. With previous weather records on incident light, its availability at different canopy levels was estimated using existing ecophysiological models and then the photosynthetic rates at canopy level were estimated. Maximum rate of photosynthesis and quantum yield (photosynthetic efficiency) decreased with the increase in depth of the canopy whilst it was vice versa for the convexity of light response curve. In general, parameters of LRC were superior in RRIC 121 to RRIC 100. Irrespective of the clone, a greater proportion of leaves was found in the top than in the lowest stratum. Leaf area index in RRIC 121 was greater than RRIC 100 with values of 5.88 and 3.47, respectively. Light extinction coefficient was less in RRIC 121 allowing more light to penetrate through the canopy than in RRIC 100. The capability of sequestering atmospheric CO2 was greater in RRIC 121 than that in RRIC 100 with annual rates of 117 and 45 MTha-1, respectively. On average, mature rubber is capable of sequestering 81 MT of CO2 per hectare annually and, within the 24 years of mature phase, 1,296 MT of CO2 would be sequestered in a hectare of rubber.Item Harvesting the rubber tree once in four days: a solution to current issues in the rubber industry in Sri Lanka(Rubber Research Institute of Sri Lanka, 2011) Rodrigo, V.H.L.; Kudaligama, K.V.V.S.; Fernando, K.M.E.P.; Yapa, P.A.J.Item Field performance of young coffee seedlings and cuttings intercropped with rubber(Rubber Research Institute. Agalawatta, 1988) Rodrigo, V.H.L.; Nugawela, A.; Kariyawasam, L.S.; Aluthhewage, R.K.Coffee may be planted either using seedlings or cuttings. Anyhow, a comparative study of their field establishment and performance has not been made. Iin this study seedlings and cuttings of Coffea canephora intercropped with rubber were compared for their field stablishment and growth. It is evident that there is no difference in the success of their field establishment. The dry matter yield determinants of plants, i. e. light intercept ion, conversion efficiency and rate of loss of dry matter, estimated by total leaf area, CO2 assimilation rate and dark respiratory rate respectively, are also similar in both seedlings and cuttings. This is confirmed by the similar mean total dry weight of a seedlings and a cuttings. The partitioning of assimilates is more towards root development in the cuttings and is evident by the significantly high root dry weight and the root/shoot ratio. The percentage of assimilates partitioning towards the growth of aerial parts is less in the cuttings, i. e. 52 and 67perc. for cuttings and seedlings respectively. Despite of similar light levels, the CO2 assimilation rates are lower in the afternoon in both seedlings and cuttings. The perc. deeline is 23.5 and 18.6perc. for seedlings and cuttings respectively.Item An economic evaluation of the use of rainguards(Rubber Research Institute. Agalawatta, 1993) Rodrigo, V.H.L.; Herath, P.H.M.U.; Nugawela, A.Use of rainguards can minimize the loss of tappping days and hence the loss in rubber crop. A simple model was developed to study different components determinig the profitability of using rainguard is discussed. Price of rubber, yield potential of a plant and tapping wage rate were identified as most important factors which determine the worthiness of the use of rainguards. Sealent price is also a major factor in deciding profitability. If the price of scalent is less than Rs. 20/= per kg, the profilability from both the apron and the gutter types is sameItem Is shade important in rubber based cropping systems? Part 2.: photosynthetic performance of rubber and banana under natural shade(Rubber Research Institute. Agalawatta, 2002) Senevirathna, A.M.W.K.; Stirling, C.M.; Rodrigo, V.H.L.; Karunathilake, P.K.W.; Pathirana, P.D.Item Effect of planting density on growth, yield related factors and profitability of rubber (Hevea brasiliensis Muell.Arg.)(Rubber Research Institute of Sri Lanka. Agalawatte, 1995) Rodrigo, V.H.L.;Data available on an experiment on planting density of rubber in Kalutara region of Sri Lanka were analyzed in view of investigating how planting density affects yield, yield related factors and financial return. Experimenet comprised six planting densities from 400 to 920 trees per hectare and three clones PB 86, RRIC 101 and RRIC 103. Planting density has affected plant girth of all clones from fourth year onwards. Density effect on girth of RRIC 101 was higher than that of other clones. With increasing planting density bark thickness and number of latex vessel rings declined in all clones and relatively more marked in clone RRIC 101. Similarly, yield per tree per tapping decreased, but yield per hectare per tapping and net present value increased with the increase in density. Nevertheless, with only two years of yield data and also without knowing number of tapping days for each density tested, it is not possible to arrive at definite conclusions. Less variation in girth increment among different densities towards later stage of plant growth indicates that apparent effect of density in this stage could be a cumulative effect over the period but not the effect of this stage. No density effect on canopy light interception was evident. Available data justifies further investigations and it is suggested that more adoptability trials located in different agro-climatic regions are to be conducted using new clones before arriving at definite conclusions. In these srudies due consideration should be given to tappable stand, incidence of tapping panel dryness and tapping days.Item Adoption of different tapping systems in the rubber industry of Sri Lanka with special reference to low frequency tapping(Rubber Research Institute . Agalawatta, 2007) Rodrigo, V.H.L.Item Rubber cum sugarcane intercropping. a sustainable cropping system for farmers in the intermediate zone of Sri Lanka(Rubber Research Institute. Agalawatta, 2000) Rodrigo, V.H.L.; Nugawela, A.; Sivanathan, A.; Witharama, W.R.G.; Jayasinghe, W.K.Item Rubber/timer intercropping systems and their impact on the performance of rubber(Rubber Research Institute. Agalawatta, 2002) Rodrigo, V.H.L.; Silva, T.U.K.; Kariyawasam, L.S.; Munasinghe, E.S.