Abstract

An investigation was carried out at Tamilnadu Rice Research Institute, Aduthurai during Thaladi 2009 with 125 advanced breeding lines of 23 rice cross combinations to study the nature and magnitude of genetic divergence through mahalanobis D 2 statistics. Observations were recorded on important panicle traits viz., panicle length, number of filled grains per panicle, panicle exertion and 100 grain weight. The breeding lines were grouped into 42 clusters. The cluster I contained highest number of genotypes (40) followed by cluster II, XXXXI, and XXXXII which had three genotypes each, the remaining 39 clusters had two genotypes each. The intra cluster distance was highest in cluster XXXXII (14.59), followed by cluster XXXXI (14.28) and cluster II (14.12). It was the lowest (0.66) in cluster III. Highest inter cluster distance was noticed between clusters XXXX and XXXV (30.35), followed by clusters XXXX and XXX (30.30), cluster XXXX and XXVIII (30.05) and lowest between clusters XIII and IV (2.04). Hundred grain weight contributes 57.67 per cent and panicle exertion contributes 19.60 per cent to the total genetic divergence. From this study it was concluded that sufficient amount of variability was observed among the breeding lines developed in the crosses viz., ADT 43/ Tapaswini, ADT 46 (R)/ IET 17917, ADT 39/ AD 02202, ADT 39/ Kalinga, ASD 19/ T 317 which may be used as parents to produce highly heterotic and superior transgressive segregants upon hybridization for important panicle traits.

Keywords: Genetic diversity, D 2 statistics, panicle traits, rice.