Journal of the Rubber Research Institute of Sri Lanka

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19882

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    Secondary characters and their association with latex yield in Hevea brasiliensis(Mull Arg.)
    (Rubber Research Institute. Agalawatta, 1988) Olapade, E.O.
    Ten Hevea clones developed at the Rubber Research Institute Of Nigeria (RRIN) and a control clone RRIM 600 were evaluated for their latex yield after six months of tapping. The mean dry latex yield recorded for each clone was correlated with their Juvenile secondary characters i. e Height, Girth and Plant Vigour at 18 months. Significant variability was exhibited by the clones in terms of yield with clone C 83 having the highest mean latex yield of 42.15 g/t/t/ while clone C 202 had the least mean yield of 22.73 g/t/t. The secondary characters i. e Hewight, Girth and Vigour were significantly positively correlated to themselves but all negatively correlasted to latex yield. However a spurious correlation was established between latex yield and the secondary characters. The implication of the results are discussed
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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