POPULATION FLUCTUATION OF JASSID, AMRASCA DEVASTANS (DIST.) IN COTTON THROUGH MORPHOPHYSICAL PLANT TRAITS

Ten genotypes of cotton viz., BH-118, CIM-443, CIM-448, FH-634, FH87, HR-129, VH-142, SLS-1, HRVO and Okra-170 catalogued in relation to resistance against jassid, Amrasca devastans (Dist.). All the tested genotypes of cotton significantly differed in relation to all morphological plant traits. From ten genotypes, Okra-170 afforded appreciable resistance and was found comparatively the most resistant genotype to jassid attack. While FH-634 showed the highest susceptibility to adult jassid. While maximum nymph population was noticed on FH-634 and minimum on HRVO and same is the case with adult + nymph population. The last two weeks of August and first two weeks of September were found to be the most favourable for the development of jassid nymph and adult population. Hair density on vein and lamina of upper leaves, the length of hair on midrib and vein of upper leaves, midrib of middle leaves and midrib and vein of bottom leaves, gossypol glands on midrib, vein and lamina of upper, middle and bottom leaves and thickness of leaf lamina on midrib and bottom leaves played a significant and negative role towards resistance for jassid adult population. The length of hair on midrib, vein of middle leaves, gossypol glands on lamina of middle leaf was resulted to significant and negative correlation with jassid nymph population while all the other morphological traits showed non-significant correlation to jassid population.