Reaction of rice genotypes to brown spot disease pathogen Cochliobolus miyabeanus under drought conditions

Cochliobolus miyabeanus is the causal agent of rice brown spot disease, responsible for significant economic losses. The best way out to overcome the disease is the development of resistant lines. In present studies a set of 31 rice genotypes was evaluated in field against brown spot disease under low water application conditions. The experiment was conducted at National Agricultural Research Centre, Islamabad during 2011. The crop was sown by dibbling in a non-replicated experimental design using the susceptible line as check. The check entry was repeatedly sown after two test entries. The disease data were recorded on 1-9 rating scale. The reaction of various lines to brown spot was quite divergent depending upon the genetic resistant of genotypes. The disease severity ranged from 1 to 9. The susceptible check was badly hit by disease and scored 9. The lines HHZB, IR80416-B-32-3, IR84677-34-1-B and HHZ11-Y6-Y1-Y1 were found to be highly resistant against brown spot by scoring 1. It was interestingly noted that all the late lines did not show any symptoms of disease while all the medium and early maturing lines have shown response against disease. In view of present investigation, it may be suggested that above 4 resistant lines may be brought forward and involved in rice breeding program for development of brown spot resistant lines.