Journal of the Rubber Research Institute of Sri Lanka
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Item 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 Effects of pottasium and magnesium on leaf and bark nutrient contents of young Hevea brasiliensis(Rubber Research Institute. Agalawatta, 1989) Weerasuriya, S.M.; Yogaratnam, N.Leaf and bark analyses provide evidence of uptake of K and Mg from applied K and Mg fertilisers respectively. Efficiency of uptake appears to have however been influenced by the level of applied K and Mg, pre - treatment K and Mg content of the soil and sources of Mg. Significant antagonistic effects between K and Mg fertilisers on leaf K and Mg have been recorded. Both K and Mg fertilisers were also found to decrease the Ca content in the leaf except when dolomite was used as the source of Mg. It appears that bark analyses could also be used as a tool for indicating the K and Mg status of young Hevea plantsItem Utilization of phosphorus from apatite and growth of plants inoculated with vesicular arbuscular mycorrhiza and phosphate dissolving bacteria(Rubber Research Institute. Agalawatta, 1990) Pathirana, L.S.S.; Waidyanatha, U.P. De S.; Peiris, O.S.An annual grass, Pennisetum ploystechyon (L) Schult and a perennial creeping legume Pueraria phaseoloides took up more P and grew better in an acid soil (pH 4.8) treated with a poorly soluble source of apatite. Inculation of the sterilized soil with a heterogenous mixture of a vesicular arbuscular mycorrhizal (VAM) spores extracted from the soil and with Glomus fasciculatus (E3) spores did not increase plant growth or uptake of P in soil with apatite but growth was increased considerably in soil in soil without apatite. However, inoculation with E3 type spores had no effect on growth or P uptake of Pennisetum . Phosphate dissolving bacteria (PDB) stimulated growth of Pueraria and uptake of P from a soil enriched with apatite.Item Clonal differences in rock phosphate utilization by Hevea(Rubber Research Institute. Agalawatta, 1991) Dissanayake, D.M.A.P.; Dissanayake, T.; Gunasekera, R.; Jayasekera, S.Genotypic variability in utilization of rock phosphates including the local source Eppawale was evaluated using Hevea clones during the early immature phase. All the clones responded to P fertilization, and the responces were related to the source of fertilizers and other soil characteristics. Plants of clone RR1C 121 utilized Eppawala rock phosphate efficiently, both in Matale and Boralu soil. But, plants of clone RR1C 110 were able to use both rock phosphate sources only in Matale soils. However, responce to rock phosphate from plants of 100 was comparatively low in relation to P uptake and dry matter production. The necessity of testing these clones for the locally available phosphate source in the field scale is also discussedItem Effect of combined nitrogen on growth and nodule function or Pueraria phaseoloides(Rubber Research Institute. Agalawatta, 1991) Jayasinghe, C.K.; Wettasinghe, D.S.Nodulation and nitrogen fixation rates of most of the legumes are reported to be severely affected when they are grown in soils high in available nitrogen. Furthermore, this phenomenon may become more critical when legumes are grown in multiple cropping systems like Pueraria phaseoloides in rubber plantatons where ono legume counterpart is fertilized with nitrogenous fertilizer. Results of experiments conducted in seeding agar to find the effect of nitrogen on growth and nodule function of P. phaseoloides showed that nodulation of P. phaphaeoloides was inhibited at a concentration between 24.4 and 44.8 ppm nitrogenItem Role of rock phosphates in the nutrition of immature and mature Hevea(Rubber Research Institute. Agalawatta, 1994) Dissanayake, D.M.A.P. othersCommercially available Eppawela rock phosphate (ERP) was evaluated as a source of P for young rubber plants throughout the period of immaturity. The effects of rock phosphate on yield nutrient composition of leaves soil were also studied on mature rubber.The efficiency of ERP in relation to growth of young plants was similar to that of Imported Rock Phosphate (IRP) Triple Super Phosphate (TSP) when used in soils with a P status less than 37.00 Kg of soils with a soil pH range of 3.6 to 4.2. In these situations it appears that the currently recommended rate of P is unlikely to be sufficient to meet the plant P demand.It is therefore possible to use ERP as a source of P for immature rubber plants growing in areas which are considered low in P for rubber.In contrast, application of rock phosphates did not influence the productivity of the mature rubber tree.plants were able to maintain adequate levels of P in leaves even under no P fertilizer conditions suggesting the effect of residual P in soil that received IRP during the immature phase.Item Fertilizer use among perennial crops(Rubber Research Institute of Sri Lanka. Agalawaththa, 1982) Peries, O.S.; Yogarathnam, N.Item Some issues related to sustainability in the smallholder rubber sector(Rubber Research Institute . Agalawatta, 2007) Wijesuriya, W.; Dissanayake, D.M.A.P.; Herath, K.; Edirisinghe, J.; Abeywardene, V.