Heterosis and combining ability estimates for okra (Abelmoschus esculentus L. Moench) varieties for yield attributing characters in Sudan savanna of Nigeria

Abstract

Two location trials were conducted at the Teaching and Research Farm of the University of Maiduguri and screen house of the Faculty of Agriculture during 2018/2019 dry season to estimate the combining ability variance, general combining ability (GCA) effects of parents and specific combining ability (SCA) effects of crosses with six okra genotypes. They include: three improved varieties NHAe 47-4, LD-88, Clemson spineless and three locals, Chalawa, Syria and Sola, crossed in a 3 x 3 line x tester mating design to generate nine F1 hybrids. All the F1s along with their parents were evaluated in a Randomized Complete Block Design (RCBD) and Completely Randomise Design (CRD), with 3 replications. Positive heterosis were observed for number of fruits per plant in the crosses Chalawa x NHAe47-4, Chalawa x Clemson Spineless, this directly indicated their important contributions toward total fruit yield in okra. The variance of GCA and SCA revealed that both additive and non-additive gene actions were important in the control of most agronomic.The ratio of GCA/ SCA indicates greater preponderance of non-additive gene action for the characters in all the traits except number of leaves per plant and days to 50% flowering which were controlled by additive gene actions. The parent Syria was the overall best general combiner among the lines for all characters in the field and Chalawa was the overall best general combiner for all characters measured among lines in the screen house. LD88 recorded the highest GCA effects for all of the characters among testers in both experiments. Similarly, in the field, the hybrid Sola x NHAe47-4 recorded the maximum SCA effect for all characters except days to 50% flowering; Syria x NHAe47-4 was the best SCA for most characters except plant height and also the cross between Syria x Clemson Spineless was the best SCA for most characters except number of fruits per plant. In the screen house, the cross between Chalawa x NHAe47-4, showed superior SCA for all characters measured. Appreciable level of heterosis was observed for most of the characters studied, the overall maximum positive significant heterosis for total fruit yield (kg/ha) was observed in crosses Syria x LD88 (52.80) and Chalawa x NHAe47-4(123.30) over better parents. The preponderance of non-additive genetic effect and the tremendous level of heterosis observed among the characters in the parents and their crosses studied would be great asset in choosing the okra varieties for intercrossing and development of hybrids varieties for commercial production of okra.