PHENOTYPIC DIVERSITY, GENETIC VARIATION AND ASSOCIATION OF MORPHO-AGRONOMIC AND BIOCHEMICAL TRAITS IN OKRA [Abelmoschus esculentus (L.) Moench] GENOTYPES IN ETHIOPIA

Abstract

Okra is considered a minor crop and has not given research attention in Ethiopia. Therefore, a key strategy to adapt to a changing climate is the development and promotion of underutilised crop species. Thus, this research was conducted to assess the genetic diversity, genetic variability, heritability, genetic advance and association of traits of okra genotypes using morpho-agronomic traits and biochemical contents. A total of 36 okra genotypes (27 landraces and 9 introduced commercial varieties) were evaluated for morpho-agronomic and biochemical and nine qualitative traits in 2018 at Melkassa Agricultural Research Center in 6 x 6 simple lattice design. Results of analysis of variance showed significant differences among genotypes for most of the traits, except number of epicalyx and fruit diameter. The genotypes had 0.57 to 1.86 kg per plant, 23.95 to 116.31 g per plant and 13.13 to 17.21% of fruit yield, seed yield and fat content of seeds, respectively. The genotypes had total protein content varied from 4.51 to 24.79%. Genetic distances estimated by Euclidean distances from 25 traits of 36 okra genotypes ranged from 3.26 to 14.95 with mean, standard deviation and CV of 7.23, 1.82 and 25.13%, respectively. The genotypes were grouped into 13 distinct clusters from Euclidean distances matrix using Unweighted Pair-group Methods with Arithmetic Means (UPGMA). Cluster X consisted of 8 (22.22%) genotypes, while, cluster I, II, V, VI, IX, XI, and XII contained each one genotype. Cluster IV and VII had 3 and 6 genotypes, respectively. Results of principal component analysis indicated the first six principal component axes accounted 5.34 to 33.17% and a total of 74.65% to the total variation. Estimates of genotypic (GCV) and phenotypic (PCV) coefficients of variation ranged from 3.58 to 46.31% and 4.83 to 46.35%, respectively. Heritability in broad sense (H2) and genetic advance as percent mean (GAM) estimated in the range between 33.63 and 99.81% and 4.29 and 95.45%, respectively. Estimates of GCV, PCV, H2 and GAM were high for number of branches, inter nodes length, fresh fruit weight, number of mature pods, seed yield per plant and seed protein content. Fruit yield had positive and significant genotypic and phenotypic correlation coefficients with stem diameter, plant height, leaf length, leaf width, peduncle length, fruit length, fresh fruit weight, hundred seed weight, seed yield per plant and ash content. Path coefficient analysis indicated that fresh fruit weight, fruit length, seed yield per plant, leaf length and stem diameter had positive direct effects and also exerted positive indirect effects through other traits on fruit yield per plant at genotypic and phenotypic levels. This suggested the direct selection for these traits and fruit yield is effective in okra breeding programs. In conclusion this study showed the presence of genetic variation among genotypes for most of the traits including fruit yield, seed yield and nutritional content of seeds indicating selection of genotypes could be effective to develop okra varieties for high fruit yield and good nutritional content.