Assessment of cotton germplasm against CLCuD at different locations and determination of inheritance patterns for resistance

Leaf curl virus disease of cotton is major hindrance in cotton production in Pakistan for last many years. To counter leaf curl disease an experiment was designed to screen out new local and exotic germplasm from different institutes of the country and neighboring countries like Turkey and India to find out the tolerance level of 71 cotton genotypes. The genotypes were sown in the month of June using randomized complete block design and sick plot technique at two locations i.e., Faisalabad and Vehari (hot spots). The variety FH-118 was used as spreader line in this experiment. The lines naming FH-490, FH-444, FH458, VH-363 and varieties like FH-142, NIAB-878, FH-Lalazar, VH-327 provided very good results at both locations under virus infested conditions with better yield and low infection of virus. The screening criterion was based on virus tolerance and performance of genotypes with respect to superior boll numbers, sympodial branches and boll weight along with plant height and fibre quality. For the assessment of inheritance pattern of CLCuD resistance, nine selected parents including 6 females and 3 male testers were crossed using a line × tester mating system followed by line × tester analysis to further evaluate the combining ability of different crosses. The ability of parents to combine well for CLCuD % revealed that FH-490 (-9.69) followed by FH-444 (-9.23) showed negative and highly significant estimates among lines while among testers, FH-142 (- 9.66) remained highly significant and negative. Specifically, the negative and highly desirable estimates were provided by the cross combination namely FH-490 × VH-327 (-8.95), FH-458 × FH-142 (-7.81), VH-363 × FH-Lalazar (-6.90), MNH1016 × VH-327 (-5.09), FH-490 × FH-142 (-4.17). Dominance variance was higher than additive variance for most of the characters studied including CLCuD tolerance. The results concluded that the identified parents and crosses obtained can further be manipulated for future breeding aimed at CLCuD tolerance in Pakistan and all over the world.