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Abstract

A study was carried out in ten oriental clones of Hevea hrasiliensis, planted in a clone evaluation trial in Tripura (North East India) to understand the clonal variation and environmental influence on phenotypic expression of yield and related traits during two peak yielding seasons. Phenotypic coefficient of variation for plugging index (PI), inorganic phosphorus (Pi), sucrose content (SC), total volume (TV) and dry rubber yield (RY) was high when compared to that for initial flow (IF), dry rubber content (DRC) and total, solids content (TSC). Mean performance of clones RRI1 105, RRIM 600 and PB 235 was better for yield and related traits. These clones had less outflow of sucrose indicating better efficiency of metabolism. Stability of clones decreased with better yielding nature, except for RRIM 600, which showed better stability. GT1 and RRII118 showed higher stability for most of the traits. The 10 clones were grouped into three clusters using non-hierarchical Euclidean cluster analysis. Cluster I included high yielding clones RRII 105, RRM 600 and PB 235, cluster II consisted of RRII 118, RRII 203, PB 86 and GT 1 which were medium yielding clones and cluster III comprised the low yielding clones RRIC 105, GI 1 and Harbel 1. Average inter cluster distance showed that cluster III was more divergent from clusters I and II. Phenotypic variation in the character expression for yield of clones was considerably influenced by factors, which were associated with senescence and low temperature reaction. The clones, which were stable and high yielding like RRM 600 would be more desirable for this region.