Genetic divergence in sorghum genotypes

摘要

Sorghum (Sorghum bicolor L.) is the most important food and fodder crop of dry lands in India. In order to realise substantial production and improvement in this crop, studies on genetic divergence deserves special attention. The knowledge of genetic diversity is important for successful selection of parents for hybridization work. Hence, survey of the same in the selected available genotypes is a must (Bhat, 1970). For the present study, multivariate analysis of Mahalanobis D~2 statistics was used. Seventy five genotypes of sorghum (Sorghum bicolor L) were taken for the study from the germplasm bank maintained at the Department of Millets, Tamil Nadu Agrl. University, Coimbatore. These genotypes were raised in a randomized block design with two replications in Millet Breeding Station during summer 1997. Observations were recorded for days to 50 per cent flowering, days to maturity, 100 grain weight and grain yield per plant on five randomly selected plants of each genotype in each replication. The data were subjected to multivariate analysis (Rao, 1952). The original mean values were transformed to normalized variables and all possible D~2 values were calculated. For determining group constellations or clusters, a relatively simple criteria Tochers method was followed. After establishing the clusters, intracluster distances and inter cluster distances were worked out. The genetic distance between the clusters was arrived by taking the square root of the average D~2 values. (Mahalanobis 1936).