Genetic diversity estimates and stability analysis in common bean (Phaseolus vulgaris L.) germplasm of Jammu and Kashmir

Abstract

Seventy five common bean genotypes were selected in the present study for their morphological characterization, estimation of genetic variability and other genetic parameters, presence of genetic diversity at phenotypic level and genetic distance at the molecular level (using RAPD primers) and stability of some selected genotypes. The experimental material was evaluated in a Randomized Complete Block Design with three replications at three locations, namely Pulse Research Sub-station, Habbak (E-I), Regional Research Station and Faculty of Agriculture, Wadura, Sopore (E-II) and Krishi Vigyan Kendra, Pombay, Kulgam (E-III) during kharif 2008 for genetic divergence and other genetic parameters and in four random environments during kharif 2009 for stability. Morphological traits of qualitative nature viz., growth habit, leaf characters, stem colour, flower colour, flowering pattern, branching pattern and seed characters were scored, which indicated presence of sufficient variability with respect to these traits. Analysis of variance revealed presence of significant genetic variation among these genotypes for all the traits. G x E interaction was also significant, revealing that genotypes did not perform equally across all the three locations. Genotypic coefficient of variaiton (GCV) was high for seed yield plant-1; moderate for days to 50 per cent flowering, days to maturity, number of pods plant-1, pod length, number of seeds pod-1 and 100-seed weight and low for other traits. For all the traits, estimates of phenotypic coefficient of variation (PCV) were higher than genotypic coefficient of variation (GCV), indicating presence of environmental influence. Heritability estimates (bs) were high for days to 50 per cent flowering, days to maturity, number of pods plant-1, pod length (cm), 100-seed weight (g), seed yield plant-1 (g) and protein content (%). Seed yield plant-1 exhibited a significant positive association with number of branches plant-1, number of pods plant-1, pod length, number of seeds pod-1 and 100-seed weight and negative association with days to 50 per cent flowering and maturity at both the levels. Estimation of genetic divergence using Mahalanobi’s D2 among bean genotypes was highly significant, while these genotypes got grouped into six, ten and eleven clusters in E-I, E-II and E-III, respectively, but in pooled analysis these genotypes were grouped into three cluster with cluster-I having 23 genotypes, cluster-II (1) and the remaining cluster was monogenotypic. Inter-cluster distance was maximum between clusters-III and IV in E-I, cluster-IV and VII and E-II, cluster-IV and VI in E-II and cluster-I and cluster-III in pooled analysis. The maximum contribution for divergence came from days to maturity (22.52%) followed by 100-seed weight (14.63%), protein content (12.60%), seed yield plant-1 (11.21%) and days to 50 per cent flowering (10.46%). Molecular characterization of thirteen common bean genotypes was done with Random Amplified Polymorphic DNA (RAPD) markers. Initially 15 primers were screened out of which only seven were selected which generated a total of 65 amplification products out of which 63 bands (96.62%) were polymorphic indicating fair amount of polymorphism. The genotypes shared 43% genetic similarity among themselves. Cluster analysis delineated the genotypes into three groups with seven, five and one genotype in cluster-I, II and III, respectively. The maximum similarity index (82.35) based dice similarity coefficient was obtained between SKUA-R-21 and SKUA-R-19, while it was minimum (27.72) between genotypes PBG-29 and SKUA-R-01. Stability analysis of seventeen common bean genotypes for seed yield plant-1 across 4 random environments revealed that mean square deviation from regression (S2di) was non-significant for SKUA-R-05, SKUA-R-11, SKUA-R-12, SKUA-R-16, SKUA-R-19, SKUA-R-25, SKUA-R-28 and PBG-03 and hence prediction of stability for these genotypes were precise and reliable. The linear regression (bi) was non-significant for SKUA-R-12 and SKUA-R-28 revealing that these cultivars were average in stability. Comparing their performance with the mean, it was observed that SKUA-R-28 was well adapted to all the environments and SKUA-R-12 was adapted to poor environments