Abstract
Clonal stability of tree dryness was evaluated in eleven clones of Hevea brasiliensis at the Rubber Research Institute of Nigeria. The experimental design was the randomized complete block with three replicates and ten trees per replicate. The clones were evaluated in three locations. Four stability parameters were applied. The stability parameters were: environmental variance, regression index, variance due to regression, and Shukla's stability variance. Clone C 202 was outstanding for clonal stability and could be useful for further studies and genetic improvement of tree dryness. Other four clones (C 76, C 150, C 159 and RRIM 600) were also stable.
Highlights
The main product obtained from Hevea brasiliensis is latex, which has been the main focus of genetic improvement ever since commercial exploitation of natural rubber started (Pushparajah, 1995)
Eleven clones of Hevea brasiliensis were evaluated for tree dryness at experimental sites of the Rubber Research Institute of Nigeria (RRIN)
The strong influence of the environment on clonal variation was manifested through the significant clone x environment interaction (Table 1)
Summary
The main product obtained from Hevea brasiliensis is latex, which has been the main focus of genetic improvement ever since commercial exploitation of natural rubber started (Pushparajah, 1995). It has been suggested that tree dryness is a syndrome arising from a number of dysfunctional factors in the plant (Das et al, 1998), and significant genotype x environment interaction has been reported for it (Omokhafe and Aniamaka, 2000). Intra-clonal variation, which obscures clonal character, is a common feature in the incidence of tree dryness in Hevea brasiliensis (Sivakumaran et al, 1994). Stability is a measure of clonal performance over a number of environments.
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