Genetic divergence in new plant type rice under shallow lowland ecosystem

摘要

Genetic diversity among 56 'new plant type' lines including four improved cultivars was studied using Mahalanobis D-2 statistic under shallow lowland ecosystem. The genotypes were grouped into 11 clusters showing fair degree of relationship between geographic distribution and genetic divergence. Cluster I with 23 genotypes was the largest followed by cluster IV with 12, cluster VII with 10 genotypes, and cluster IX with 4 genotypes, while cluster II, III, V, VII, VIII, X, and XI were monogenotypic. Genotypes in cluster IX had highest intra-cluster distance followed by cluster IV and VII while highest inter cluster divergence was between cluster VII and XI followed by that between VI and XI. Maturity duration contributed maximum to the total divergence. Other traits with appreciable contribution to total divergence were spikelet per panicle (no.), grain filling (%), panicle number/m(2), panicle length (cm), and harvest index (%). All the minimum and maximum cluster mean values were distributed in relatively distant clusters. The members of clusters VIII, V, IV VI, X, VI, and I may be further evaluated, as these clusters are observed to possess high cluster mean for grain yield. Further, it is suggested that cross combinations of IR73964-120-5-3-2 x IR72164-110-1-2, IR73964-120-5-3-2 x IR72967-12-2-3, IR75282-58-1-2-3 x IR71701-28-1-4-3, IR75268-45-2-5-3 x IR71676-106-10-3, IR75282-58-1-2-3 x IR72967-12-2-3, and IR73964-120-5-3-2 x IR71701-28-1-4 showing high D-2 matrix value are expected to produce superior progenies.