Genetic diversity in wheat genotypes under early heat stress in Bangladesh

Abstract

Twenty-four wheat (Triticum aestivum L.) genotypes/lines were assessed in alpha lattice design with three replications during winter season of 2014-15 at the Regional Wheat Research Centre (RWRC), Bangladesh Agricultural Research Institute (BARI), Rajshahi. The main aim of this experiment was to find out the degree of genetic diversity for characters related to early heat tolerance in wheat. Five different clusters were formed among the genotypes. The number of genotypes in cluster I and V were same i.e. three and they formed the smallest cluster. The cluster III was the largest containing eight entries followed by the cluster IV that contained six genotypes and cluster II also had four members. The inter-cluster distances ranged from 3.4496 to 6.8221 and principal component analysis scores also showed that the genotypes had a wide range of genetic diversity. The maximum inter-cluster distance was observed between the clusters IV and V (6.8221) after that cluster I and IV (5.8935) and clusters III and V (5.2913) respectively. The maximum inter-cluster distance value showed that the genotypes under cluster IV were far diverged from the cluster V. Also, the genotypes under the cluster pair I and IV and cluster pair III and IV were far diverged. The genotypes were genetically closed in between cluster III and IV (3.4018), cluster I and V (3.4496), cluster I and II (3.6163) and cluster II and IV (4.1373) due to their minimum inter-cluster diversity. However, the highest spike length, spikelets spike⁻¹ and grain yield were found in cluster I may show high heterosis for grain yield. The characters; short growing period, dwarf stature and bold grain were aggregated in cluster IV may show higher heterosis for dwarf stature and earliness. Canonical variate analysis (CVA) revealed that The traits 1000-grain weight and spike length had the highest contribution towards the divergence due to their positive values in both vectors. Based on these results, the genotypes under cluster I, cluster V and cluster IV might be taken for selecting suitable parents or crossing combinations for future early heat tolerance wheat breeding program.