Studies on resistance to jassid (Amrasca biguttula biguttula Ishida) in different Bt hybrids Cotton

The biochemical factors in Bt hybrids of cotton imparted resistance and exercised great influence on infestation of the pest. The less susceptible Bt hybrids Ankur-3228, Ankur-3224 and 73 CO1 had high amount of gossypol and soluble protein content. The value of correlation coefficient (r) for gossypol and soluble protein suggested significantly strong negative correlation with jassid incidence (r =-0.82**, -0.07) with low moisture and tannin. The values of correlation coefficient (r) for moisture and tannin indicated strong positive correlation (r = 0.83**, 0.85**) in relation to jassid infestation. Susceptible Bt hybrids of cotton MH-5361, NCS-1446, VBCH-1537, Western108, ZCH-545, ZCH-547, NSPL-252, RCH-2, SWCH-4708, VBCH-1542, SP-1171 and IAHH-2, recorded maximum jassid infestation and were found to contain high moisture and tannin. Higher activities of oxidative enzymes viz., polyphenol oxidase and peroxidase were observed in less susceptible Bt hybrids. Highly significant and negative correlation (r =-0.79**, -0.80**) were found between oxidative enzymes and jassid infestation.