Yield Reduction Index Method to Isolate Pest Resistant Varieties of Cotton (Gossypium hirsutum, L.)

Abstract

Yield reduction index (YRI) as a short-cut-method for the isolation of pest resistant varieties of cotton (Gossypium hirsutum, L.) was set up as the percentage reduction of yield of seed cotton under full plant protection of the seed cotton yield under non-protected condition. YRI close to zero indicates resistant variety while high value indicates the excessive susceptibility of a variety. In this study yield reduction index (YRI) varied from 0.338 to 0.651 in early and 0.105 to 0.482 in late group respectively. Early group with closer spacing showed high mean YRI (0.519) as compared to YRI (0.292) for late group with wider spacing indicating that the early varieties are relatively more susceptible to insect disease complex than the late group.