Abstract
Genetically engineered cotton genotypes, Gossypium hirsutum L., (Bt-121, Bt-196, Bt-313, Bt-333, Bt-496, Bt703, Bt-802, Bt-1524, Bt-3701, Bt-W1) were evaluated for their resistance against whitefly, Bemisia tabaci
(Genn.), during the cropping seasons 2008 and 2009. In 2008, Bt-496 showed highest susceptibility to B. tabaci
(4.52 population/leaf) followed by Bt-121(3.55 population/leaf) and Bt-3701 (3.19 population/leaf) while all the
remaining varieties were statistically at par having minimum population per leaf ranging from 1.97 to 2.75. In
2009, Bt-496 showed highest susceptibility to B. tabaci (4.97 population/leaf) followed by Bt-333 (4.25
population/leaf) while all the remaining varieties were statistically at par having population ranging from 2.09 to
3.59 per leaf except Bt-703 which showed highest resistance to B. tabaci (1.41/leaf). Four physico-morphic
characters of the leaves viz., gossypol glands, hair density, hair length and lamina thickness were also studied of
the subjected cotton genotypes. In 2008, lamina thickness and gossypol glands were positively correlated with
mean B. tabaci population/leaf (r = 0.66; r = 0.67 respectively) whereas in 2009, hair length and gossypol glands
showed negative and positive correlations respectively (r = -0.65; r = 0.78). Minimum temperature and wind speed
were negatively correlated while sunshine had a positive impact on B. tabaci population.
