Genetic divergence among indigenous rice (<i>Oryza sativa</i> L.) genotypes of Kerala based on anaerobic germination and early seedling growth

Flooding during germination severely hinders rice establishment in direct-seeded rice. One hundred and fifty rice genotypes indigenous to Kerala were evaluated for key traits including anaerobic germination potential under submerged conditions and its early seedling growth. Significant variability was observed among the traits under study, with germination per cent, shoot length and vigour indices registering high heritability and thereby indicating strong genetic control on expression of these traits. Genetic divergence studies by Mahalanobis D2 analysis grouped the genotypes into 11 distinct clusters, with notable inter and intra-cluster distances, indicating considerable diversity. The study identified cluster III with 22 genotypes and cluster VI with three genotypes as clusters with promising genotypes. The results thus provide a reliable basis for parental genotype selection in breeding programs focusing on developing genotypes suitable for direct seeded rice systems through improvement of anaerobic germination tolerance. A hybridization program involving parents from these identified clusters is likely to produce a higher frequency of promising segregants or favourable combinations, which can be utilized for developing valuable genetic stocks or new varieties.