Genetic Diversity Analysis for Bacterial Leaf Blight Disease Resistance in Rice (Oryza sativa L.)

Rice (Oryza sativa L.) gets affected by more than seventy diseases by the infection of bacteria, fungi and viruses. Among, bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv oryzae (Xoo) is the important disease around the rice cultivated areas and causing drastic yield losses ranging between 20 and 30 per cent. Among very few options for increasing yield potential in rice, genetic diversity among the genotypes plays an important role in selection of parents having wider variability for disease resistance.

The rice genotypes were screened using PDI for bacterial leaf blight (BLB) and subjected to D² analysis for nine quantitative traits viz., plant height, number of productive tillers per plant, panicle length, days to fifty per cent flowering, number of grains per panicle, thousand grain weight, grain length, grain breadth and single plant yield.

On the basis of Mahalanobis D² statistics, the thirty five genotypes are grouped into VIII clusters. The highest intra cluster distance was recorded for cluster II (41.16) followed by cluster VI (37.73). Out of thirty five genotypes screened under field condition using percentage disease index (PDI), CR 1009 found to be resistant with the lowest PDI value of 9.67 per cent. The genotypes Karsamba, TPS 4 and Kaivara samba registered highest PDI value of 70.67, 67.22 and 66.67 respectively. The BLB resistance in genotype dependent and not cluster based. The resistant genotype CR 1009 under field screening was positioned in VI cluster. The cluster II had susceptible genotypes karsamba and kaivarasamba. Thus, the identified genotypes can be utilized in recombination breeding to provide BLB resistance segregants.