Assessment of Different Traits to Evaluate Genetic Divergence in Some Wheat (<i>Triticum aestivum</i>L.) Genotypes under Late Sowing Condition

The research work was undertaken to identify the extent of genetic diversity in different parameters of wheat related to heat tolerance mechanism. Performances of currently available 25 spring wheat genotypes were studied at the Regional Wheat Research Institute, Shyampur, Rajshahi during the winter season of 2016/2017. All these genotypes (25) were grouped into five clusters on the basis of non-hierarchical clustering parameters viz. cluster I (G2, G5, G6, G16, G20), II (G4, G7, G9, G11, G12, G17), III (G10, G24), IV (G1, G13, G19, G21) and V (G3, G8, G14, G15, G18, G22, G23, G25). These groups were arranged into five (5) pairs of clusters viz. cluster I and III;II and III;II and V;III and IV;IV and V considering their similar potentiality of different traits. Results revealed that the maximum number of genotypes (8) was found in cluster V while cluster III comprised minimum genotypes (2). The inter-cluster distance was higher than intra-cluster distances. The highest and second highest eigenvalues belonged to spike/m2 (25.23%) and spikelets/spike (20.18%) respectively, along with positive canonical values in both the vectors 1 and 2 for these two traits identified them as major traits by exposing their highest potential toward genetic divergence. Cluster III produced the highest spike/m2 (388.8), grain/spike (48.1), plant height (89.5 cm), SPAD (54.2), yield (2799 kg/ha) and biomass (7758.1 Kg/ha) with lowest heading days (64.7 days), maturity days (98.7 days), canopy temperature at vegetative stage (21.7°C) and canopy temperature at grain filling stage (22.4°C). In contrast, cluster V produced the lowest 1000-grain weight (30.4 g) and grain yield (2172 kg/ha) belonging to the highest canopy temperature at both stages (23.8°C and 24.7°C). However, results suggested that the genotypes G10 and G24 under the cluster III, and genotypes G01, G13, G19 and G21 under the cluster IV could be considered as parents for future hybridization program, as well as the five pairs of clusters viz. cluster I and III;II and III;II and V;III and IV;IV and V might be matched as considered for getting more heterotic F1. The results of the study would help to identify the divergent genotypes associate with heat tolerance and this might be helpful in designing future breeding program.