Multivariate analysis through d²statistic among free threshable mutants of tetraploid wheat (Triticum sp.)

Assessment of genetic diversity using quantitative traits has been of prime importance in many contexts particularly in differentiating well defined populations and hence present study was undertaken to estimate genetic diversity among the free threshable lines of tetraploid wheat {Triticum sp.) derived through induced mutagenesis. During rabi 2009–10, 101 free threshable mutants which are in M₄ generation with checks DWR 1006, DDK 1001 and DDK 1025 were evaluated in RCBD with two replications at Dharwad. Mahalanobis'S (1936) D² statistic analysis was used for assessing the genetic divergence among the test entries. It was observed that days to maturity was the single largest contributor (64.34%) towards divergence followed by plant height (9.80%). Cluster pattern revealed that cluster I consisting of 82 genotypes (81 mutants and check DWR 1006) was the largest followed by clusters II, III and IV with 11,7 and 2 mutants and 1 each in clusters V and VI with checks DDK 1001 and DDK 1025, respectively. Many free threshable mutants grouped in cluster I with check DWR 1006 may be due to durrumization of free threshable mutants. Considerable amount of genetic diversity in the material representing different mutagenic treatments revealed no relation between mutagenic treatment and genetic diversity. Maximum differences among the genotypes within the same cluster were shown by cluster IV (D² =5.47) and clusters V and VI had no intra-cluster distance (D²=0.00) as they were represented by single genotype. When diversity among the clusters was studied, it showed a range of 5.90 to 12.84. Clusters II and III showed maximum inter-cluster distance (D²= 12.84) and lowest inter-cluster distance was noticed between clusters I and V (D²=5.90).