Journal of the Rubber Research Institute of Sri Lanka
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Item Nutrition and fertilizer use in Hevea and associated covers in peninsular Malaysia - a review(Rubber Research Institute. Agalawatta, 1977) Pushparajah, E.The paper reviews some of the latest findings on nutrition of Hevea and effects of fertilizer on latex properties. It also considers work on increased efficiency in use of fertilisers. The latter includes studies on effect of fertilisers on soil properties and availability of fertiliser residues. The use of appropriate covers and their management to increase their efficiency is considered. Additionally, the influence of the covers on the nitrogen nutrition of Hevea is discussed. The information available indicates that the applications of inorganic N fertilisers could be avoided for up to 8-109 years of tapping, with consequent economic benefits.Item Effect of leaf litter on direct and indirect mobilization of P from apatite(Rubber Research Institute. Agalawatta, 1987) Pathiratne, L.S.S.; Waidyanatha, U.P. De S.; Peries, O.S.Leaf litter as direct and indirect means of improving P availability from apatite was tested. Application of leaf litter impo=roved the P uptake by indicator crops but did not influence the availability of P from applied apatite.Item Responses of five tropical pasture species to application of apatite(Rubber Research Institute. Agalawatta, 1986) Pathiratne, L.S.S.; Waidyanatha, U.P. De S.; Peries, O. S.Shoot growth and phosphorus content of Pueraria, Centrosema, Stylosanthus, Panicum and Paspalum were best at 500ppm and better at 100ppm than at zero ppm apatite. Root growth on the other hand was stimulated at 100ppm and marginally inhibited at 500ppm.Both relative shoot and root growth responses were least for Styl;osanthus which showed a notable ability to take up P from untreated soil compared to the other species. This may be related to its greater calcium uptake ability as evidence d in much higher calcium concentrations in its shoot than in the other. The grasses recovered for more P from both treated and untreated soil than the legumes.Item Native root-nodule bacterial populations in rubber growing soils and forest soils(Rubber Research Institute. Agalawatta, 1986) Jayasinghe, C.K.; Parker, C.A.; Kulasooriya, A.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 Diurnal variation in nitrogenase activity of common cover crops in rubber plantations of Sri Lanka(Rubber Research Institute. Agalawatta, 1989) Jayasinghe, C.K.; Parker, C.A.; Kulasooriya, S.A.Diurnal fluctuations in nitrogenase activity (acetylene reducing activity) have been observed in several nitrogen fixing systems. All experimental plants viz. P. phasides D. ovalifolium and M. invisa demonstrated diuanal rhythm withlight intensity. The lowest acetylene reduction activiteswere detected around midnight and they were activelyu fixing nitrogen by 8.00 am. M. invisa responded to high soil temperature in addition to light intensity. A marked drop in acetylene reduction activity was observed by about 4.00pm when the soil temperature was around 38ºCItem 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 Seasonal variations in nodule activity of Pueraria phaseoloides (Roxb) Benth(Rubber Research Institute. Agalawatta, 1990) Jayasinghe, C.K.; Parker, C.A.; Kulasooriya, S.A.The age of Pueraria phaseoloides plants had a marked effect upon the rate of acetylene reduction in their nodules. Acetylene reduction activity increased with the age of the plant and maximum efficiency of nodule activity was detected 60 days after sowing, followed by a marked decline on the 120th day and continued at a low rate. Dry matter yield and total nitrogen in plants was more or less constant thrugh out the assay period.Item 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 Management of covers under Hevea in Sri Lanka(Rubber Research Institute. Agalawatta, 1977) Yogaratnam, N.; Sulaiman, H.; Karunaratne, A.D.M.; Peiris, K.S.A.C.Results of two experiments, comparing the effects of leguminous creepers and naturals as ground covers on growth of immature rubber, are discussed. In one experiment the growthof rubber in plots under pure legume covers was better than that under naturals. Applications of extra nitrogen to trees in plots with natural covers improved their growth but the latter was not comparable to that in legume plots. In the pther experiments the increase in growth of rubber with higher levels of fertiliser nitrogen was observed irrespective of the type of cover. Application of phosphate to covers led to better tree girths than where the phosphate was applied on the trees, irrespective of the type of cover grown. These results are discussed in relation to the nitrogen content of rubber eaves, green matter, litter and C/N ratio of the litter of cover.