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1986 - 19902

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Author: search.filters.author.Aluthhewage, R.K.Subject: search.filters.subject.Rubber

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    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.
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    The effect of tapping on the assimilation rates of Hevea brasiliensis Muell. Arg. leaves
    (Rubber Research Institute:Agalawatta, 1990) Nugawela, A.; Aluthhewage, R.K.
    The CO2 assimilation rates at leaf level were compared in tapped and untaped trees of two Hevea brasiliensis genotypes. In both genotypes, the CO2 assimilation rates of the leaves in the upper stratum were lower in tapped trees. Simmilary, in young microtapped plants the CO2 assimilation rates were lower than in the untapped plants. The decrease in CO2 assimilation rates due to tapping cannot be attributed to an increase in either stomatal or mesophyll limitations. Tapping increases the sink demand for photo assimilates, but it also results in the loss of water, inorganic nutrients and proteins from the plant. Loss of water, inorganic nutrients may results in lower CO2 assimilation rates of the tapped trees. In the long-term this could result in lower sucrose content in the latex. This may be a probable cause for the physiological disorder, tapping panel dryness in rubber.