STUDIES ON GENETIC VARIABILITY AND TRAIT RELATIONSHIP IN CASTOR (RICINUS COMMUNIS L.)

Abstract

Castor oil plant (Ricinus communis L.) is one of highly treasured industrial oil crop around the world. In the present study, genetic variability and trait relationships in some castor genotypes were examined to generate information for castor breeding purposes in Nigeria. Ten castor genotypes were evaluated in a Randomized Complete Block Design with three replications at the Research Farm of Niger State College of Agriculture, Mokwa, Nigeria. The analysis of variance results showed significant differences among the germplasm for all the traits studied, except leaf petiole length. The seed yield (kg/ha) ranged between 411.11 kg/ha and 1140.00 kg/ha with average of 852.19 kg/ha. High (> 20%) genotypic and phenotypic coefficient of variations were observed for days to 50% flowering, number of branches per plant, number of effective racemes per plant, effective raceme length, number of capsules per raceme and height at maturity. Positive and significant genotypic correlations were found between the seed yield, and number of effective racemes per plant (0.501**), effective raceme length (0.402**), number of capsules per raceme (0.361**) and 100 seed weight (0.560**). Positive direct effects on the seed yield were observed for nine out of thirteen traits studied. The cluster analysis grouped the genotypes into two main clusters with 4 and 6 cluster members. Based on these findings, it is showed that there is adequate genetic variability in the castor genotypes evaluated. The findings on the trait relationships revealed the raceme characters as important traits for indirect selection for increase in seed yield of castor.