ABSTRACT

Field experiments were conducted in 2005 and 2006 to evaluate the performance of seven varieties of okra (Lady Finger, Clemson Spineless, Agwu Early, NHAE 47-4, TAE38, Jokoso and LD88) for selection in southeastern Nigeria. The experiments were laid out in a Randomized Complete Block Design (RCBD) in four replications. The evaluation block occupied a land area of 16.4m x 21.8m. Sixteen characters were studied and the result showed that Lady Finger recorded the highest performance for plant height, leaf area, length of peduncles, length of pods, fresh weight of pods, dry weight of pods, number of seeds per pod, number of ridges per pod, and number of seeds per ridge and was followed by Clemson Spineless for number of leaves per plant, fresh weight of plants, number of pods per plant, 1000 seed weight and fresh pod yield, while Agwu Early recorded superior performance for number of branches and girth of pods. Diallel crosses were made to determine heteroses, genetic components, heritability, genetic advance and the general combining ability (GCA) and specific combining ability (SCA) in the expression of sixteen characters. Significant differences (P<0.01) were observed among the varieties and their F1 hybrids in all the characters studied. The highest positive mid-parent and better parent heteroses of 363.01% and 131.51%, respectively were given by the F1 hybrids of Lady Finger x Jokoso for number of branches. For better parent heterosis, the F1 hybrids of Jokoso x LD 88d' recorded 96.02% for fresh weight of pods, the F1 hybrids of Clemson Spinelsx Agwu Earlyc1 recorded 76.02% for dry weight of pods, while the F1 hybrids of Agwu Early x Lady Finger recorded 86.90% for number of pods per plant. Similarly, the F1 hybrids of Clemson Spineless x Agwu Early recorded 40.56% for 1000 seed weight, the F1 hybrids of LD88x Lady Fingerc had 80.59% for fresh pod yield, white the F1 hybrids of Lady Finger x Jokoso recorded 131.51% for number of branches per plant. The F1 progenies were selfed to obtain F2 generations whose variances were large which indicated that the 42 F2 generations contain wide variability and could be exploited for genetic improvement and selection in okra. Large positive SCA, which ranged from - 0.01 to 1674.24 were obtained, with Lady Finger x CSc3' recording largest SCA for number of leaves per plant, leaf area, number of pods and number of branches, followed by the F1 hybrids of Jokosd x Lady Fingers in three characters: fresh pod yield, number of seeds per pod and number of seeds per ridge, while Lady Finger x NHAE 47 -4 c' recorded largest positive and significant SCA for fresh weight of plants and number of branches. The largest positive GCA effects were recorded by Lady Finger for plant height, leaf area, length of peduncles, length of pods, fresh weight of pods, dry weight of pods and number of seeds per ridges, followed by Clemson Spineless for number of leaves per plant, 1.000 seed weight, fresh pod yield, fresh weight of plants and number of pods per plant. Agwu Early showed large GCA for number of branches per plant and girth of pods, while NHAE 47-4 recorded large GCA for number of seeds per pod and number of ridges per pod. Due to large GCA, Lady Finger, Clemson Spineless, Agwu Early and NHAE 47-4 could be used as parental materials in the production of okra hybrids. The large additive genetic variance, high narrow sense heritability and genetic advance recorded for 1000 seed weight, number of pods per plant, leaf area, number of seeds per pod, length of pods, number of leaves per plant, fresh weight of pods and plant height suggest that early generation selection would be effective for genetic improvement in okra. Low additive and low narrow sense heritability estimates for other characters suggest the presence of non- additive genes in the control of those characters. High additive variance and high broad sense heritability observed for some characters suggest that pedigree method would be an effective means of improving them.