Combining ability analysis and heterosis in a diallel cross of okra (Abelmoschus esculentus L. Moench)

The genetic basis of yield and its components were studied using a 9 × 9 diallel cross techniques according to Griffing’s Method 2, Model 1 in 2007. The 36 F1’s and the 9 parents were evaluated in 2 locations; Mubi and Yola in Adamawa State, Nigeria, in 2008 wet season in a randomized complete block design (RCBD) replicated 3 times. The result showed significant entries, parents and crosses mean squares for all traits in the pooled analysis, suggesting that the okra population was highly variable for all the traits and therefore, would most likely respond to selection. Significant GCA (general combining ability) and SCA (Specific combining ability) variances were also obtained in all the traits, implying that both the additive and non-additive gene effects operated in the genetic expression of the traits. The nonadditive gene effect was however greater in magnitude as shown by the GCA and SCA ratios which were all less than unity. Combining ability analysis of parent also revealed that Mothol-AE2, Mothol-AE3, Gerio-AE1 and Mothol-AE1 gave consistently high general combining ability effects for most of the traits, indicating that their cross combinations will produce desirable segregates for the improvement of yield. Both mean performance of crosses and SCA effect identified Mothol-AE2 x Mothol-AE3, Mothol-AE1 × Mothol-AE3, Mothol-AE2 × Gerio-AE1 and Mothol-AE2 × Mothol-AE1 as the best crosses. Therefore, the mean performance of parents and crosses can be used to predict high general combining ability of parents as well as high SCA effects and heterotic effects of the crosses. The hybrid Mothol-AE2 × Mothol-AE3 exhibited heterosis of up to 23.3% in yield per plant over the higher yielding parent. This showed high performance of the hybrid over the best parent.