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Item Shoot tip culture as a method of micropropagation of Hevea(Rubber Research Institute:Agalawatta, 1988) Gunatilleke, I.D.; Samaranayake, C.Shoot tips of Hevea from aseptically grown seeedlings were established in culture on Murashige and Skoog (MS) liquid medium with half strenth salts, supplimented with BAP +IBA or MS solid medium, with full strenth salts with and without BAP + IBA. BAP was found to be better for axillary bud proliferation and growth than the other cytokinines. Proliferation of buds improved with successive subcultures. A multiplication rate of 30 + 2 shoots per explant was obtained with threee subcultures in 165 daysItem Effect of potassium and magnesium on growth of young Hevea brasiliensis(Rubber Research Institute:Agalawatta, 1988) Weerasuriya, S.M.; Yogaratnam, N.The effect of potassium and magnisium fertilisers on growth of young Hevea brasiliensis were studied using clones PB 86, RRIC 100, RRIC 103, and RRIC 121 with the objective of determining the requirement of these elements during the early phase of establishment of these clones. Three commercial fertilisers were evaluated as of magnesium. Potassium requirement of clone PB 86 during the first year was found to be approsimately 33g K/plant/year. It was found that clones. RRIC 100 and RRIC 121 needed higher amount of K than PB 86 for normal growth. Potassium application caused an overall reduction in growth of clone RRIC 103 where the soil K level was 0.07 me./100g suggesting that this level is adequate for this clone during its first year of growth. Total dry weight was significantly increased when Mg application was increased from 11 to 22g/plant/year in clone RRIC 103 but such effects were not seen in clones PB 86, RRIC 100 and RRIC 121Item An analysis of growth patterns of Hevea clones(Rubber Research Institute:Agalawatta, 1988) Margret, H.A.W.; Abeyasekera, S.; Jayasekera, N.E.M.Four girth measurements collected over four years, before tapping from ten Hevea clones grown in two sites have been analysed to study the growth pattern. Year to year variation in both sites was mainly due t linear component of growth. Growth of individual clones too was mainly due to linear effect. But some clones in one site showed significant quadratic and or cubic component. This was due to non linear growth of plants in some plots. Ten clones have been groued (a) according to the when averaged over four years so that clones within a group have the same average girth and (b) on the gradient of the regression fitted to the girth measurement increasing over the four years. RRIC 52 had the fastest growth in both sites. RRIC 103 had the same growth rates in both sites suggesting that it has a greater stability to local environmental changes.Item Clonal differences in growth parameters of young Hevea buddings and their relation to field performance(Rubber Research Institute:Agalawatta, 1986) Nugawela, A.; Aluthhewage, R.K.Hevea trees when tapped exhibited a depression of girth increment and canopy growth. Hence a high growth rate is required to maintain the growth whilst giving a high yield. Growth parameters of 5 Hevea clonal buddings were determined after different growth intervals viz., 3, 6 , 9, and 12 months to study the correlation they show with the field performance of the same clones. Clonal differences were significant, but did not necessarily correlate with the field performance. Growth rates gradually increased with age during the peeriod of investigatiion. Thepossibility of using growth parameters together with gas exchange capacities determinedin earlier studies in predicting later field performance are discussed.Item Effect of different levels of supplemental nitrogen on CO2 assimilation rates and productivity of Pueraria phaseoloides (Roxb) Benth and Desmodium ovalipolium (prain) wall. ex ridely grown in agalawatta series soil(Rubber Research Institute:Agalawatte, 1985) Nugawela, A.; Jayasinghe, C.K.; Aluthhewage, R.; Wettasinghe, S.Plant dry matter production is linked to CO2 assimilation rates, respiratory losses and total leaf area. Experiments were undertaken to determine the effect of different levels of supplimental nitrogen given to legume cover crops, on their CO2 assimilation rates and productivity. They were found to be highest for Pueraria phaseoloides and Desmodium ovaliforlium when given around 140 and 35 ppm of supplimental nitrogen. Reciprocal of specific leaf area and laef nitrogen content were also determined and they showed a positive linear relationship with supplemental nitrogen levels. How nitrogen could a influence the CO2 assimilation rates of cover crops studies are discussed.Item The management of plant diseases with special reference to Hevea(Rubber research Institute:Agalawatte, 1984) Peries, O.S.; Liyanage, A.De S.Item Observations on the development of the sporophore of Rigidoporus lignosus and the release and germination of basidiospores(Rubber Research Institute of Sri Lanka:Agalawaththa, 1982) Liyanage, I.; Peries, O.S.; Liyanage, A. de S.; Wettasinghe, C.Item Fertilizer use among perennial crops(Rubber Research Institute of Sri Lanka:Agalawaththa, 1982) Peries, O.S.; Yogarathnam, N.Item Plant growth substances in agriculture(Rubber Research Institute of Sri Lanka:Agalawatta, 1985) Samaranayake, C.Item Brown bast incidence of Hevea brasiliensis(Rubber Research Institute of Sri Lanka:Agalawatte, 1986) Wickremasinghe, S.I.