Genetic Diversity of Bread Wheat (Triticum aestivum L.) Using the Multivariate Analysis in Normal Irrigation and Drought Stress Conditions

The present investigation was carried out in the fields located at wheat breeding section, Dr Rajendra Prasad Central Agricultural University, Pusa, Samastipur and Bihar. The experimental materials of the study comprised of 39 diverse bread wheat (Triticum aestivum L.) genotypes. The genotypes were grown under two environments viz., drought stress (rainfed) and irrigated (well-watered). The experiment in each environment was laid out in Randomized Block Design (RBD) with three replications. Five plants were selected randomly from each plot for recording observations on traits viz., days to fifty per cent flowering, days to maturity, plant height, spike length, flag leaf area, relative water content (RWC), chlorophyll content, canopy temperature, number of tillers per plant, number of grains per spike, 1000 grain weight, harvest index and grain yield per plant. Germination percentage and seed vigour index (SVI) were recorded in laboratory condition. The 39 genotypes of bread wheat were grouped into seven clusters using Tocher method in both drought stress and irrigated conditions. The genotypes in cluster III and cluster VI, due to maximum inter-cluster distance between them, exhibited a high degree of genetic diversity and thus may be utilized under inter varietal hybridization programme (transgressive breeding) for getting high yielding recombinants in drought stress condition. Similar inter varietal crosses may be attempted between genotypes in cluster III and IV and cluster III and V in a drought environment. The maximum inter-cluster distance was observed between cluster IV and VI followed by cluster III and IV and cluster VI and VII in irrigated condition indicating the chances of getting high yielding recombinants would be better if the crosses are made among the genotypes of these groups. Cluster VI was suitable for grain yield, number of tillers per plant, number of grains per spike, harvest index and chlorophyll content in both environment (drought and irrigated). Therefore, the selection of parents from this cluster for these traits would be effective. Under stress, the genotypes viz., GW 2007-80, WR 1872, NAIW-1607, NAIW-1342 and WR 1743 were found promising as indicated by low drought susceptibility index.