Components of variance and interaction between genotype and environment for annual girth increment in rubber tree

Abstract

To determine the nature and extent of genetical and environmental control of vigour through annual girth increment in rubber trees [Hevea brasiliensis (Willd. ex Adr. de Juss.) Müell. Arg.], seven clones were studied in a replicated trial in São Paulo State at four different locations. The clones represented a range of imported germoplasm while the locations were selected to represent a range of rubber growing areas. Trees were studied for annual girth increment over five years before the initiation of tapping for latex. The results of the analyses show a consistent decrease in genetic component over the five years from 10 per cent to 0.5 per cent with a corresponding increase in the effect of environment (19.0 per cent to 93.0 per cent). The genotype x environment effects from combined analysis were significant for three factor analysis of variance. Genetic correlations between locations for annual girth increment revealed a consistent positive and significant correlation between Mococa and Matão in the fifth year (r_g= 0.7128), Ribeirão Preto and Matão in the fifth year (r_g=0.7113) and Ribeirão Preto and Presidente Prudente in the fourth year (r_g=0.9367). The implications of these findings in selection of rubber for annual girth increment trait are discussed.