Four field experiments were conducted at the Teaching and Research Farm of the Department of Crop Science, University of Nigeria, Nsukka to: (i) improve the photoperiodic response, especially in local (late) maturing varieties of Okra; (ii) estimate heterosis and heritability for improved yield and productivity; (iii) determine combining ability and gene effects of 13 genotypes of okra; (iv) estimate gene effects of quantitative traits; (v) determine inheritance pattern of qualitative traits for improved fruit production. The experimental materials used were three local varieties (Ele Ndu, Ele Ogwu, Ele Uhie) collected from local farmers in Nsukka LGA, Enugu State; and ten improved varieties (LUDU V., Esculentus V, Jokoso, Agwu Early, TAE 38-Dwarf, V-21 Ivra, Clemson spineless, LD88 V., V.35 and NHE 47-4 V) from the National Institute for Horticultural Research and Training (NIHORT), Okigwe, Imo State. General combining ability of the parents and specific combining ability of the hybrids were estimated using Griffings’ model 1 method 2 in a 5 x 5 diallel crosses. Chi square statistic was used to test for the inheritance pattern and degree of significance in traits of interest. ‘Ele Uhie’ parent showed significantly (p < 0.05) higher branch length, number of fruits/branch, number of fruits/plant, number of flowers/plant, plant height at maturity and total fruit yield/ hectare (123.7 cm, 8.31, 29.76, 9.03, 237.66 cm and 32.56 t/ha, respectively) than the other parents. ‘Agwu early’ parent had lower days to 50% germination, days to flower bud initiation, days to anthesis, days to 50% flowering, days to first fruiting, days to fruit maturity and plant height at maturity (4.00, 22.21, 47.13, 48.31, 51.10, 52.28 and 57.8 cm). ‘Ele Uhie’ showed significantly (p < 0.05) higher 100 seed weight (5.19 g), dry fruit weight (11.46 g), fruit girth (11.10 cm), fruit weight (34.5 g), number of ridges/pod (11.33) and number of seeds/pod (120.57). The cross ‘UHIE x LD88’ had significantly (p < 0.05) higher number of branches/plant (7), number of fruits/branch (8.64), number of fruits/plant (35.63), number of flowers/plant (10.16) and total fruit yield/hectare (38.25 t/Ha). Higher negative better parent heterosis values were observed in the cross, ‘UHIE x CLM’ in days to 50% germination (-46.32), days to flower bud initiation (-49.26), days to anthesis (-46.54), days to 50% flowering (-45.12), days to first fruiting (-45.12) and days to fruit maturity (-35.05). The cross ‘OGW x LD88’ had higher positive BPH value in total fruit yield/hectare (161.26). Narrow sense heritability in total fruit yield showed values above average in all the crosses except ‘AGW x CLM’, ‘AGW x LD88’, ‘CLM x LD88’, ‘OGW x CLM’ and ‘UHIE x CLM’. ‘Ele Uhie’ was the best general combiner for number of branches/plant (0.65), number of fruits/branch (2.01), number of fruits/plant (2.37), number of fruits/stem (3.75) and total fruit yield (9.97). ‘Ele Uhie’ was the best general combiner in days to flower bud initiation (-7.18), days to anthesis (-7.46), days to 50% flowering (-8.11), days to first fruiting (-7.46) and days to fruit maturity (-8.43). The cross, ‘UHIE x LD88’ was the best specific combiner for number of fruits/branch (3.31), number of fruits/branch (0.7414), number of fruits/plant (9.34), number of flowers/plant (2.53) and total fruit yield (10.26). The gene effect for total fruit yield showed significant positive additive, dominance and additive x dominance gene effects occurred in all the crosses with the exception of ‘UHIE x AGW’, ‘UHIE x CLM’ and ‘UHIE x LD88’. The relative proportion of additive gene effect was important for high heritability estimates recorded. This suggests that its contribution to the inheritance of earliness is ideal for developing desired hybrids. The medium-long and green with pink patched fruits predominated in the F2 populations and the observed ratio mostly fitted the expected ratio of 3:1. The hybrid ‘UHIE x LD88’ with significantly higher yield potential has the potential for commercial cultivation after further selection.