Field screening of rice genotypes for resistance against bacterial leaf blight and brown spot under aerobic condition

A field screening of eighty seven rice genotypes consisting of new breeding lines as well as some local check varieties was carried out during kharif 2011 at ICAR Research Complex for Eastern Region, Patna to identify elite rice genotypes grown under water scarcity (Aerobic) condition, having resistance against Bacterial leaf blight and Brown spot caused by Xanthomonas oryzae pv. oryzae and Cochliobolus miyabeans respectively. Significant differences were observed for resistance to both the disease among genotypes. The screening revealed that none of the breeding lines of rice was immune or highly resistant against both the diseases. Only few genotypes were shown resistance against bacterial leaf blight disease and brown spot. Lowest infestation against leaf blight was observed in IR 83387-B-B-109-4-89-3 with a disease scoring 4.7%. The genotypes IR 83387-B-B-109-4-89-3, IR 84899-B-182-3-1-1-3 and IR 84899-B179-13-1-1-1 showed highest grain yield with a value of 4.23 t/ha, 3.97 t/ha and 3.85 t/ha respectively. Rice genotypes viz. IR 83929-B-B-291-3-1-1, IR 83867-B-B-250-3-1-1, IR 84887-B-155-40-1-1, IR 84899-B185-16-1-1-1, IR 83920-B-B-277-2-1-1-1, IR 83387-B-B-109-4-89-3 and IR 84899-B-179-16-1-1-1 showed resistance to leaf blight and brown spot under aerobic condition. The grain yield was significantly and positively correlated with harvest index, biomass, tiller number, and test weight under aerobic conditions. The genotypes IR 83387-B-B-109-4-89-3, IR 84887-B-155-40-1-1 and IR 83867-B-B-250-3-1-1 showed resistance to brown spot and bacterial blight and out yielded in grain yield which may be further utilized as the genetic sources in multiple disease resistance rice breeding programme.