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Item Variations involved in field measurements of transpiration rates and stomatal diffusive resistance of Hevea brasiliensis Muell. Arg. clones and the relationship of the latter with net photosynthetic rates(Rubber research Institute. Agalawatte, 1984) Nugawela, A.; Wickremasinghe, W.N.; Aluthhewage, R.K.Variance components and their percentage contribution to total variation during field measurements of stomatal diffusive resistance (DR) and transpiration rates (TR) were studied for Hevea clones. Variance from the plant component was much higher than other components viz., leaves of the same plant and determinations of the same leaf. DR, TRand coefficient of varian for DR and TR varied significantly with leaf age and time of the day. The three leaflets in a leaf were similar in respects to DR and TR. Within a whorl, the comparatively smalle leaves at the top of differed significantly withrespect to DR and TR from the rest. DR and Tr of clones RRIC 100, RRIC 103, RRIC 45, PB 86 and IAN 710 were significantly different at 0.1perc. level. Initial studies show stomatal diffusive resistance to have a tendancy to be correlated with net photosynthetic rates (NPR). Other possible factors that might bring about clonal differences in NPR are discussed.Item Tapping panel dryness. trends and future challenges(Rubber Research Institute of Sri Lanka. Agalawatta, 2009) Senevirathna, A.M.W.K.; Nugawela, A.Item Gas exchange parameters for early selection of Hevea brasiliensis Muell. Arg(Rubber Research Institute. Agalawatte, 1985) Nugawela, A.; Aluthhewage, R.K.Selecting high yielding progeny from Hevea breeding programmes is a money and time consuming approach and limits the progress of breeding, Girth, bark thickness, numberof lates vessel rings, latex vessel density and first few years yield of 7-8 year old Hevea budding are reported to be correlated to the yield potential. These parameters are used by some breeeders for a primary selection using smalle scale clone trials. Latex is biosythesised from sucrose in latex vessels and the potential of sucrose supply to latex vessels depends on CO2 assimilatory capacity of the canopy and the partitioning of assimilates. Attempts were made to estimate the mean CO2 assimilatory capacity of a healthy and a matur eleaf whole in year old Hevea clonal buddings. Preliminary studies show the mean CO2 assimilatory capacity of a whole and its ratio with water use efficiency value to be correlated qith yield potential. These observation suggest that effective selection of clones for further testing in large scale clone trials could be done on this basis, when buddings are around a year old.Item The correlation between branching and the tree growth of Hevea brasiliensis (Muell.Arg.)(Rubber Research Institute of Sri Lanka. Agalawatte, 1996) Seneviratne, P.; Nugawela, A.; Ramawickrama, D.The main objective of the present study was to see whether there is a correlation between the number of branches and the tree grwoth in hevea brasiliensis. Considerable variation in brancing habits is observed among the trees of different clones. Also, some clones such as RRIC 121 show less brancing when compared to other clones such as RRIC 100 indicating brancing is also a clonal characteristic. Canopy architecture too, shows differences among trees within a clone. Highly significant positive correlation was observed between the number of branches and the tree girth for all clones tested for trees aged from one year to seven years. The correlation between the canopy distribution (grouped as very good, good or poor) and the tree girth was also positive.Item Shade effects on photosynthesis of cinnamon (Cinnamomum verum J. Pres)(Rubber Research Institute. Agalawatta, 1998) Pathirana, L.S.S.; Nugawela, A.; Samarasekera, R.K.Item Physiological yield determinants of sun and shade leaves of Hevea brasiliensis Muell. Arg(Rubber Research Institute of Sri Lanka. Agalawatte, 1995) Nugawela, A.; Ariyawansa, P.; Samarasekera, R.K.