Estimation of genetic parameters for rubber yield and girth growth in a synthetic population

Abstract

Rubber tree (Hevea brasiliensis) breeding programs take a long time and it is costly to create, evaluate and select superior progenies of cross breeds. Consequently, this study assessed a synthetic population of 288 rubber tree clones selected from a seedling orchard and derived from five female parent trees (varieties AVROS 2037, BPM 1, IAN 873, PB 260 and RRII 118) that were useful for systematically enhancing cross-pollination among several clones and for breeding superior rubber genotypes. The genetic parameters were estimated of rubber yield and tree girth growth within each synthetic population. Variance components and genetic parameters were estimated using average information restricted maximum likelihood procedures. The estimated additive genetic variances of rubber yield and tree girth growth were greater than the permanent environmental variances and residual variances of the studied population. The results indicated a narrow-sense heritability estimate based on individual values of 0.608±0.029 and repeatability of 0.633±0.027 for rubber yield; and 0.913±0.007–0.927±0.006 for girth growth (repeatability ranged 0.965 ± 0.003–0.982 ± 0.002). Genetic correlations between rubber yield and tree girth growth traits were positive (r_g = 0.63–0.64). There was also a positive phenotypic correlation (r_p = 0.48–0.49) between the rubber yield and girth growth traits. These results indicated that this synthetic population is a superior progeny with the potential for improving both rubber yield and tree girth growth.