Effect of wild abortive cytoplasm inducing male sterility on resistance/tolerance against brown plant hopper and white backed plant hopper in basmati rice hybrids

One hundred sixteen F1 crosses along with eight female (4 cms or A lines viz.; IR68280A, IR72788A, IR70372A & IR58025A and 4 maintainer or B lines viz.; IR68280B, IR72788B, IR70372B & IR58025B) parental lines were sown during wet season 1999 in the screen house of Entomology Division at IRRI. The difference in mean reaction of cms (IR68280A) and its maintainer (IR68280B) line against brown plant hopper was negative and highly significant while the difference in mean reaction of the other cms (IR72788A) and its maintainer (IR72788B) line was non-significant. In case of F1 crosses of IR68280A & B, out of 16, 11 A x R crosses showed better mean score than their corresponding B x R crosses. Only two F1 (A x R) crosses exhibited similar reaction to their corresponding B X R crosses and only three F1 (A x R) crosses showed poor mean score than their corresponding B x R crosses. In case of IR72788A & B, out of 12, four F1 (A x R) cros ses showed better mean score and five showed poor mean score than their corresponding B x R crosses while remaining three F1 (A x R) crosses exhibited non significant difference in their mean score as compared to their respective B x R crosses indicating non association of wild abortive cytoplasm of cms line, IR68280A with the susceptibility to brown plant hopper. In case of white backed plant hopper, the two cms lines viz. IR70372A & IR58025A indicated non significant difference in their mean score as compare to their corresponding maintainer or B lines. The comparison of F1 crosses of IR 70372A & B revealed that 9 out of 16 F1 (A x R) crosses showed significantly better mean score and 3 A x R crosses showed poor mean score than their corresponding B x R crosses. In two cases, the difference in mean score of F1 crosses (A x R & B x R) was non-significant and in two cases there was no difference al all. In case of other cms line, IR58025A & B, 9 out of 14 F1 ( A x R) crosses exhibited significantly better mean score than their respective B x R crosses. In four cases there was no difference in mean score of A x R & B x R F1 crosses, Only one B x R F1 cross (IR58025B x IR67888-127-3) showed significantly better mean score than its corresponding A x R F1 cross (IR58025A x IR67888-127- 3). The inconsistent behaviour of the F1 crosses of all cms (A) & maintainer (B) lines x restorers suggested nuclear gene interaction rather than the association of wild abortive cytolplasm to susceptibility to brown and white backed plant hopper.