Journal of the Rubber Research Institute of Sri Lanka

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1988 - 19892

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Author: search.filters.author.Weerasuriya, S.M.Subject: search.filters.subject.Fertilizers

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    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 121
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    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 plants