Genetic diversity in some aromatic and nonaromatic maintainer lines based on principal component analyses for hybrid rice (Oryza Sativa L.) breeding

Genetic diversity of 21 maintainer lines ofrice was studied under rainfed condition through Mahalanobis D2 statistic for grain yield and yield contributing characters. The lines were grouped into five clusters. The inter-cluster distances were higher than intra-cluster distances indicating wider genetic diversity among the lines of different clusters. The intra-cluster distances were lower in all the cases reflecting homogeneity of the lines within the clusters. The principal component analysis showed that the first four components with vector values > 1 contributed 88.86 % of the total variations. The highest number (08) of lines was constellated in cluster V and the lowest (1) in cluster II. The intra- and inter-cluster distances were the maximum in cluster V (0.76) and between clusters II and V (18.10), respectively and the minimum in cluster IV (0.51) and between clusters I and III (4.12), respectively. The maximum value of inter cluster distance indicated that the lines belonging to cluster V were far diverged from those of cluster II. So, it is expected in our results that parent’s selection for hybridization from the clusters V and II may give the desirable heterosis for heterotic rice hybrids. Besides, the cluster mean revealed that the crosses between the lines of cluster I with clusters II and V would exhibit high heterosis for maximum good characters. Hence, only effective tiller number had maximum contribution towards genetic divergence. Besides, evaluation of yield contributing characters demonstrated that the maintainer lines under the present study possessed a considerable genetic diversity. Therefore, maintainer lines need to be conserved in gene bank for future hybrid rice breeding programs.