Heterosis, Combining Ability, Genetic Diversity and their Interrelationship in Pigeonpea [Cajanus cajan (L.) Millspaugh]

The development of superior hybrids is must to break the existing yield plateau (< 800 kg/ha) in pigeonpea and hence, the genetic mechanism governing the heterosis in pigeonpea must be decoded.

The present study was laid down using randomized block design during kharif 2018-19 at GBPUAT, Pantnagar with 36 genotypes (8 parents and 28 F₁ hybrids) of pigeonpea. The estimates of combining ability were evaluated by using the Griffing’s, Method II, Model I. The observations recorded for yield and related traits were subjected to the estimation of genetic diversity (GD) using the D₂ statistics. The correlation between heterosis and different parameters viz., parental mean (PM), specific combining ability (SCA), mean of general combining ability (MGCA) and genetic diversity (GD) were estimated by using Pearson’s correlation.

High estimates of SCA variance and more than unity (>1) average degree of dominance for all the characters indicated the presence of over dominance. The SCA followed by MGCA were found to be most reliable parameters to predict the heterosis. The parents having high × low or high × high per se performance, good × poor GCA effects and with medium genetic diversity resulted in high frequency of heterotic hybrids.