VARIATION IN GROWTH AND FRUIT YIELD OF OKRA [Abelmoschus esculentus (L.) Moench] AT DIRE DAWA, EASTERN ETHIOPIA

Abstract

Okra is one of indigenous genetic resource of Ethiopia, but only few studies were carried out to assess its variability and performance throughout the country. Therefore, it was necessary to continue the evaluation of available okra indigenous and introduced varieties to identify superior okra genotypes. Thus, this research was conducted to assess variation in growth and fruit yield of okra genotypes and genetic variability of indigenous and introduced okra genotypes for morpho-agronomic traits. A total of 21 okra genotypes (11 indigenous and 10 introduced) were evaluated for 25 quantitative morpho-agronomic and 2 qualitative traits in 2020 at Dire Dawa in randomized complete block design with three replications. Results of analysis of variance showed highly significant (P<0.01) differences for all traits except green fruit width that showed significant difference (P<0.05). The genotypes showed fruit yield ranged from 1.66 to 10.45 with mean of 6.23 tons ha-1 and seed yield per plant that ranged from 10.66 to 93.9g with mean of 46.5g. The mean performance of okra genotypes collected from south-western, north western, northern and western Ethiopia were greater than introduced varieties for fruit traits including growth, green fruit yield, fruit quality and other agro morphological traits. However, introduced varieties were early flowering and maturity than indigenous. Estimates of genetic (GCV) and phenotypic (PCV) coefficients of variation range from 9.16 to 42.3% and 9.33 to 44.16%, respectively. Heritability in broad sense (H2 ) and genetic advance as percent of mean (GAM) ranged from 29.57 to 91.89% and 10.39 to 83.53%, respectively. Estimated variability components (GCV, PCV, H2 and GAM) were high and moderate for all traits except days to 50% emergence (GCV and PCV), internodes length (GCV) and green fruit width (H2 ) that were categorized under low. The presence of genetic variability in okra is an indication of the less influence of environmental factors in the expression of traits and the higher chance to improve best traits. High H2 coupled with GAM also provides better information than each parameter alone and also an expression of additive gene action. The first four principal component axes (PCA1 to PCA4) accounted for 7.83 to 35.02% that accounted 74.56% to total variability with eigenvalues that ranged from 1.95 to 8.75. Genetic distances estimated by Euclidean distances from 25 traits ranged from 2.33 to 12.56 with mean 6.83, standard deviation 1.8 and coefficient of variation 26.46%. The genotypes were grouped into four distinct clusters from Euclidean distances matrix using UPGMA. Cluster I consisted 12 genotypes (57.14%) while cluster II consisted two genotypes (9.52%). Cluster III consisted one genotype (4.76%) and cluster IV contained six genotypes (28.57%). Okra genotypes collected from south-western, north western, northern and western Ethiopia were more divergent with high genetic distances and had higher performances for most of the traits including growth, green fruits yield and seed yield than introduced varieties. In conclusion, this study showed the presence of variation among genotypes for most of the traits indicating selection of genotypes could be effective to develop okra varieties for high green fruit and seed yield through direct selection or crossing.