The role of genetic divergence in determining heterosis in castor (Ricinus communis L.)

Abstract

Combining ability is a useful tool for choosing appropriate parents, while an understanding of the nature of gene action can help develop effective crop improvement initiatives. In order to study if genetic diversity affects hybrid vigour, 50 hybrids were generated by crossing five pistillate lines with ten testers and experimented across two replications during the 2020–21 kharif. Genetic divergence was evaluated as Mahalanobis distance among all potential pairs of lines and testers and also in relation to combining ability. Hybrids were classified into four divergent classes using statistics like distance (D2), overall gca effects among parents, overall sca effects, and midparent heterotic status across crosses. Genetic diversity studies revealed the that parents to be used in hybridization programmes should be moderately divergent, to derive crosses with high better parent heterosis. Hybrids, viz., MCP-1 × ICS-240, MCP-1 × RG-2787, MCP-1 × RG-3160, YRCP-1 × ICS-258, and DPC-22 × RG-2787, were identified as superior to standard checks for economically important traits. Superior male and female base populations can be created through random mating of lines and testers with high breeding values, such as DPC-22, MCP-1, ICP-30, RG-2787, RG-3160, RG-72, and YRC-1904, respectively.

Keywords

• genetic divergence
• combining ability
• castor
• heterosis