Combining Ability And Heterosis For Half Diallel Crosses In Cowpea (Vigna Unguiculata L.)

Abstract

The eight cowpea genotypes were used (AL_hokool, Black eyes, Italia, Gls/14, Ramshorn, JA10, JA20 and Max), which were cultivated in the spring of (2020) in order to perform the Diallel Meting Design (AA) according to the second method. (random model) proposed by Griffing (1956a). Then, The compared experiment was conducted by planting the seeds of parents and hybrids (8 parents + 28 individual hybrids) in the autumn season (2020) using a randomized complete block design (CRBD) in three randomly distributed replicates to estimate genetic parameters, the combining abilities and Heterosis for leaf area traits (cm². Plant ^-1). The number of pods. Plant-1 and the number of seeds. Pod^-1, weight of 100 seeds (g), biological yield (g) and yield of individual plant (g). The results of the analysis of variance indicated that there were significant differences at the probability level (1%) for all traits. The results showed that there were significant differences for all the traits of the general combining abilities to specific combining abilities, the ratio of the components of the general combining abilities to specific combining abilities  was greater than one for the number of pods . Plant-1traits and weighed 100 seeds (g), biological yield (g) and yield of individual plants, while the parents (4), (7) and (8) recorded significant effects in the desired direction for these traits. The hybrids x Gls/14) JA20, (x Black eyes JA20), (Ramshorn x Black eyes), (Max x Gls/14) and (Max x JA20) (Ramshorn x AL - hokool) showed the highest desirable heterosis  in All traits are based on the deviation of the first generation from the average and best parents. While the results of the analysis showed significant of zero for the values ​​of the additive and dominance variance and for all traits, while the dominance variance was greater than the additive variance for all traits except for the 100-seed weight (g) and biological yield (g). It was noticed through the values ​​of genetic parameters that the mean of the degree of dominance was greater than one for all traits except for the trait of 100-seed weight (g), while the percentage of heritability in the narrow sense was high for the two traits of 100-seed weight (g) and biological yield (g), and it was medium in the trait The number of pods. Plant^-1 and the yield of the individual plant (g).While it was decreased in traits of leaf area (cm². Plant^-1) and number of seeds. Pod^-1 . The expected genetic improvement percentage was as a high percentage in the traits of 100-seed weight (g) and biological yield, and it was average for the traits of leaf area (cm².plant^-1) and the number of pods. Plant^-1 The yield of the individual plant (g), while it was low for the number of seeds. Pod^-1.