Estimation of Genetic Variability, Correlations and Path Coefficients for Seed Yield Contributors in Castor (Ricinus communis L.)

Castor is one of neglected African oil crops with little research attention in Nigeria. In the present research, eighty-six castor genotypes were evaluated at three locations in Niger State, Nigeria. The aim was to estimate the extent of genetic variability and also to examine the associations among the seed yield and its components. The treatments were laid out in an Alpha Lattice Design with three replications. The results revealed significant effect of genotypes for most of the studied traits. Days to 50% flowering ranged between 34 days and 125 days, and had a mean of 69.21 days. The minimum of 7.33g and maximum of 64.12 were recorded for 100 seed weight. Seed yield ranged from 144.45 Kgha-1 to 1 349.92 Kgha-1 with the average yield of 646.04 Kgha-1. Spike length and 100 seeds weight showed a high Genotypic Coefficient of Variation (GCV) and also high Phenotypic Coefficient of Variation (PCV). Significant positive correlations were observed between the seed yield and plant height at flowering, branches per plant, length of spike, spike per plant, days to maturity and 100 seeds weight. The path coefficient analysis revealed positive direct effects of seedling establishment, spike length, spikes per plant, plant height at first raceme maturity, days to first raceme maturity and 100 seeds weight on the seed yield. Highest positive direct effect on seed yield was recorded in spike length, followed by spikes per plant and seed weight, respectively. Significant positive correlations and high positive direct effect were observed in spike length, spikes per plant and seed weight. The findings revealed the importance of spike characters for the selection of desirable castor genotypes for increased seed yield.