Seasonal stability and genetic divergent constellation studies in knolkhol (Brassica oleracea var. gongyloides L.)
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Date
2018-05
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Sher-e- Kashmir University of Agricultural Sciences and Technology of Jammu, Jammu
Abstract
The present investigation entitled “Seasonal stability and genetic divergent constellation studies in knolkhol (Brassica oleracea var. gongyloides L.)” was carried out at Vegetable Research Farm, Division of Vegetable Science & Floriculture, SKUAST-J, Chatha to estimate genetic variability, character association and genetic constellation and to assess the performance of genotypes across seasons. The field experiment was laid out in Randomized Block Design with three replications, spaced at 30 cm × 30 cm. Thirty genotypes were evaluated during main season (Sept-Oct) 2016-17 for 23 quantitative and qualitative traits to assess the existing variability and genetic diversity and also for molecular characterization using 20 SSR markers at School of Biotechnology, SKUAST-J. Phenotypic stability studies were also conducted in twenty five genotypes under four environments (E1: Winter season (2015-16), E2: Spring- Summer (2016-17), E3: Rainy Season (2016-17) and E4: Autumn Season (2016-17). The analysis of variance revealed significant differences among the genotypes for all the characters under study. Moderate to high heritability, high genetic advance and moderate to high coefficients of variability were observed for plant height, plant frame, leaf length, leaf width, petiole length, stalk length, net knob weight/plant, gross knob weight/plant and yield/plot indicating that these are controlled by additive gene action and could be improved by direct selection. Net knob weight/plant showed negative and significant correlation with days to marketable maturity, calcium content (knob and leaves) and potassium content (knob) while positive significant correlation with leaf length, number of leaves/plant, marketable knob diameter and gross knob weight/plant. Gross knob weight/plant exhibited highest positive direct effect on net knob weight/plant. Thirty genotypes were grouped into 6 different clusters on the basis of D2 analysis and three major clusters based on molecular data. Maximum intra cluster distance was observed in cluster III while maximum inter cluster distance was recorded between cluster IV and II revealing the presence of sufficient genetic diversity for selecting superior and diverse parents. Rajouri Local and Pusa Virat were the most diverse genotypes based on molecular data. With respect to phenotypic stability, highly significant mean sum of squares for genotypes, environments and genotype × environment interaction were recorded for all the traits except number of leaves per plant, harvest index indicating that both linear as well as non linear components were important in building up total G × E interaction. On the basis of three stability parameters as per Eberhart and Russel model (1966) genotypes G40, SJKK-04, Early White Vienna and C-2002 were capable of giving consistent performance across season for yield and yield attributing traits. Genotypes G-40, SJKK-02, SJKK-03 have been identified for early maturity, while Early White Vienna, Pusa Virat, Palam Tender Knob, Green Gold and C-2002 were stable in performance for percent harvest index. The genotype Palam Tender Knob was stable in performance for all the quality traits except calcium content (knob and leaves), while genotypes C-2002 was suitable for unfavourable environments for all the quality traits such as ascorbic acid content (knob and leaves), beta carotene content (knob and leaves), calcium content (knob and leaves), potassium content (knob and leaves) and phosphorous content (knob and leaves).
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