Performance of Bt and non-Bt cotton (Gossypium hirsutum) genotypes under cotton-wheat (Triticum aestivum) system*

Abstract

A field experiment was conducted during 2002-03 to test the performance of Bt and non-Bt cotton hybrids 'MECM 915' and 'MECI-I 162' under cotton-wheat system. Highest germination was observed in 'Om Shankar' (99.4%). Vegetative growth was higher in non-Bt than the Bt types due to high number of monopods (5-6 per plant) while sympodes (fruiting branch) were relatively higher (about 50 per cent) in Bt hybrids. 'MECH 9 15' Bt was early for days to 50 per cent flowering (57 days) and boll bursting (92 days) and maturity (1 11 days), as compared to 'MECH 162' (60,99 and 209 days, respectively). Seed-cotton yield was highest (2.25 tonnesiha) in 'MECH 915' Bt than 'MECH 162' (1.9 1 tonnes/ ha) and local hirsutum hybrid and variety (1.56 to 4.76 tonneslha). Late sowing of wheat reduced biomass, leaf area and yield of wheat (9 to 13 %) and system productivity (16 96). WEY was highest (12.1 1 tomes/ha) with 'MECN 915' Bt (cotton) - TPBW 343' (wheat) system.