Evaluation of resistance to Pyricularia oryzae in rice genotypes

Rice blast, caused by Pyricularia grisea Sacc, has been a continuous threat to rice production. Eight rice genotypes along with two checks (Nemat as resistance check and Binam as susceptible check) were evaluated for resistance to blast in 2011. The experiments were conducted under field and greenhouse inoculated conditions. The results of field experiments based on lesion type, panicle blast severity and AUDPC data for leaf and panicle blast showed that B40, Binam and IRBLZT-T genotypes are sensitive and three rice genotypes (IRBLKP-K60, IRBLZ5-CA and Nemat) possess a higher level of resistance to leaf and panicle blast. Also, FLAGMAN and GAMMA genotypes with the highest panicle infection showed significantly lower leaf blast. Grouping of rice genotypes based on greenhouse traits (lesion type and Number of sporulating lesion) by cluster analysis with Ward's method and Euclidean distance criteria classified genotypes to two groups. The first group including FLAGMAN, Nemat, IR1552, IRBLTA2-RE, IRBLKP-K60 and GAMMA genotypes had lesion type between 0.0 to 2.0, and showed resistance reaction. These genotypes could be utilized as donor parents for breeding durable blast resistant varieties. The second group including IRBLZT-T, IRBLZ5-CA, Binam and B40 genotypes had lesion type more than 2.0, showed sensitive reaction and also generated sporulating lesion.