Studies on performance of Bt cotton genotypes and evaluation of refuge crops cropping systems

Abstract

Two field experiments were conducted at Main Agricultural Research Station, newlineUniversity of Agricultural Sciences, Dharwad during the years 2003-04 and 2004-05, to newlineassess the performance of Bt transgenic genotypes and to identify the suitable refuge newlinecrops/cropping systems in Bt cotton cultivation. The experiment entitled Performance of Bt newlinetransgenic genotypes was laid out in randomized complete block design with eight cotton newlinegenotypes (MECH-12 Bt, MECH-162 Bt, MECH-184 Bt, RCH-2 Bt, RCH-20 Bt, RCH-144 Bt, newlineDHH-11 and Sahana) as treatments with three replications. Another experiment entitled newline Studies on management of Bt cotton through refuge crops / cropping systems was laid out newlinein randomized complete block design with six cropping systems (100% Bt cotton, 80% Bt newlinecotton, Bt cotton + 20% non Bt cotton, 80% Bt cotton + 20% marigold-chickpea, 80% Bt newlinecotton + 20% Okra-chickpea, 80% Bt cotton + 20% chilli and 80% Bt cotton + 20% newlinepigeonpea) as treatments with four replications in replacement series. newlineAmong the different Bt and non-Bt cotton genotypes, RCH-20 Bt recorded newlinesignificantly higher seed cotton yield than RCH-144 Bt, MECH-162 Bt, DHH-11 and Sahana. newlineThe extent of increase in RCH-20 Bt was 8.0, 13.0, 26.0, 31.0, 48.0, 92.0 and 151 per cent newlineover MECH-184 Bt, RCH-2 Bt, MECH-12 Bt, RCH-144 Bt, MECH-162 Bt, DHH-11 and newlineSahana, respectively. newlineAmong the different refuge crops/cropping systems on 20 per cent refuge cropped newlinearea, Bt cotton refuge cropped with chilli (518 kg/0.2 ha), relay cropping of marigold newlinechickpea (495 kg/0.2 ha) and bhendi-chickpea (474 kg/0.2 ha) cropping systems recorded newlinesignificantly higher Bt cotton equivalent yield than Bt cotton refuge cropped with non-Bt cotton newline(310 kg/0.2 ha) and pigeonpea (171 kg/0.2 ha). Effect of refuge crops/cropping systems on newlinetotal yield of the system was significant. Bt cotton refuge cropped with bhendi-chickpea (1637 newlinekg/ha), marigold-chickpea (1612 kg/ha) cropping systems and chilli (1526 kg/ha) recorded newlinesignificantly higher total seed cotton yield than Bt cotton refug