Study of Bio-physical characters of Bt hybrids for correlation with Cotton jassid

The bio-physical characters of Bt hybrids of cotton influenced on infestation of the pest. Among the characters influencing jassid infestation, the trichome density, the less susceptible Bt hybrid Ankur-3228 (88/cm²), while lowest (11/cm²) was observed in susceptible Bt hybrid IAHH-2. Trichome density exhibited strong and negative correlation (r =-0.90), thickness of midrib, Ankur3228 recorded minimum (1.17mm) thickness of midrib, susceptible Bt hybrids RCH-2 (1.56 mm) recorded more thickness of midrib. The strong and significant positive correlation (r = 0.64), plant height the less number of jassid population was recorded in less susceptible Bt cotton hybrids viz; Ankur-3228, Ankur-3224 and 73CO-1 which were comparatively taller than the susceptible dwarf Bt cotton hybrids viz; MH-5361, NCS-1446, VBCH-1537, Western-108, ZCH-545, ZCH-547, NSPL252, RCH-2, SWCH-4708, VBCH-1542, SP-1171 and IAHH-2. The strong significant negative correlation-0.67, the highest number of leaves were recorded in the susceptible Bt hybrids while, minimum numbers of leaves were observed in less susceptible viz; Ankur-3228, Ankur-3224 and 73-CO1 Bt cotton hybrids and exhibited non significant positive correlation (r = 0.39) in relation to infestation by Amrasca devastans, the thickness of leaf lamina, Minimum thickness of leaf lamina was observed in Bt hybrids viz; RCH-2, IAHH-2, and SWCH-4708. The strong and significant negative correlation between thickness of leaf lamina and jassid infestation observed with ‘r’ value-0.72**.