COMBINING ABILITY AND STABILITY ANALYSIS IN OKRA (Abelmoschus esculentus (L.) Moench)

Abstract

The experiments were conducted at Research and Development Farm under Metal Agro Limited, Nagarchanti, Debigonj, Panchagarh during the period from August, 2014 to March, 2017 on okra (Abelmoschus esculentus (L.) Moench). The investigation began with fifty genotypes for preliminary evaluation and identification of fruit yield contributing characters. After biometrical analyses for means, correlations and cause and effect, fruit yield per plant, four characters viz. plant height at 100 days, fruit length (cm), fruit weight (g) and number of fruits per plant, appeared as the most effective characters to increase fruit yield per plant but among the characters, fruit length showed considerable heritability (h2 b=53.30%), therefore, except this character, other three characters might improve through only selection breeding. The fifty genotypes were grouped into six clusters by D2 statistics and the genotypes collected from different sources were included in the same cluster or in different clusters, suggested migration of okra genotypes were depended upon humans settled in different regions of the world. Seven parents were selected on the basis of mean values and positive and significant GCAs and then twenty one experimental hybrids were produced from these in half diallel fashion. Out of seven parents, P3, P5 and P6 accessions showed positive and significant GCAs for fruit yield per plant. Moreover, these three accessions were separately distributed in three different clusters, and these accessions found to be excellent general combiners for the development of okra hybrids. From the set of twenty one experimental hybrids, thirteen hybrids exhibited positive and significant SCAs for fruit yield per plant but on the basis of mean performances and positive and significant SCAs. Three combinations such as P3 * P7, P2 * P4 and P5 * P6 were outstanding for increasing fruit yield in okra. The Vr-Wr graphs on thirteen characters were constructed to reveal additive, dominant, over dominant, epistatic and complementary gene interactions. No non-allelic gene interaction was observed for fruit yield per plant. Heterosis was estimated over better parent, mid parent and two check varieties, Check-1 (Green Finger) and Check-2 (BARI Darosh-1) for thirteen characters. Fruit yield per plant in three crosses showed highly significant heterosis over two check varieties. Response and stability of eight hybrids were evaluated through Eberhart and Russel model. The experimental hybrids were evaluated in four different environments viz.E1=kharif 1of 2015, E2=Kharif 1 of 2016. E3=Kharif 2 of 2016 and E4= Kharif 1 of 2017. The environmental indices revealed that E1=Kharif 1 of 2015 was the most favorable environment and E3=Kharif 2 of 2016 was the worst environment for the evaluating hybrids. The phenotypic index of the hybrid showed that, P6 (1203) * P7 (1205) with fruit yield 540.72 g/plant followed by the P5 (1189) * P7 (1205) with 469.08 g/plant and P5 (1189) * P6 (1203) with 448.18 g/plant exhibited outstanding in performance across the four Kharif seasons in between 2015 to 2017. However, the stability parameters (bi and s2di) of these three hybrids were also reasonable. Therefore, these three hybrids may be advanced with a view to release new okra hybrid varieties. Furthermore, it is suggested that Kharif 1 (March–June) is the suitable season for cultivation of okra in our country.