The present investigation was undertaken as pre-breeding objective with fifty three wheat genotypes which have potential to tolerate late heat and are suitable for late sown condition. Genotypes were evaluated for six different characters viz., tillers per meter, days to heading, days to maturity, grain number per spike, 1000 grain weight and yield per plot. Genotypes showing superiority over best check were identified as donors for respective traits. These are WR1743, WR1873, WR1872 for early heading; K0604, KYP320, KYP 522, NIAW1342, RWP2006-33, RWP2006-34 and RWP 2006-35 for grains per spike in addition to WR1695, WR1872, WR2099 for 1000 grains weight which can be further utilized in wheat breeding programme. Genetic diversity was measured by D2 statistics which showed high degree of divergence among the genotypes. All the genotypes were grouped into 11 clusters on the basis of genetic distance among them. Cluster X was the largest having twenty genotypes followed by cluster V and cluster VII having seven genotypes each.
The pattern of distribution of genotypes from diverse geographical region into different clusters was random which indicate free and frequent exchange of genetic material among the farmers and breeders of different region. Inter cluster distance was highest between cluster VII and IX showing highest divergence between them. Maximum intra cluster distance was observed in cluster XI indicating existence of wide genetic divergence among the constituent genotypes whereas intra cluster distance was minimum in case of cluster II which revealed less divergence among the constituent genotypes. Character which contributed most towards genetic divergence was yield per plot which indicate that this character might be used in selecting genetically diverse parents for hybridization programme. Cluster VII was the highest yielder in terms of mean value followed by cluster III while cluster IX was lowest yielder. So, it might be concluded that genotypes belonging to cluster VII (viz., GW 2007-80, GW 2007-92,GW 2007-98, HALNA, K 0501, K 0583, RWP 2008-31) were somewhat tolerant to late heat stress and they could be selected as a source of parent material for future breeding purposes.