Response of Bt cotton (Gossypium hirsutum L.) to varied nitrogen levels in Southern Telangana

Abstract

Field experiments were conducted during kharif 2014 and 2015 at Agricultural Research Institute, Rajendranagar to determine the optimum nitrogen level for Bt cotton in alfisols in Southern Telangana. Significantly more number of days (31, 47 and 94) was taken to attain square initiation, flowering and boll development stage, respectively and higher drymatter production (9.2, 129, 182 and 239 g plant-1) was registered at square initiation stage, flowering, boll development and first picking stages, respectively with application of nitrogen at 225 kg ha-1. Higher earliness index (0.78) was registered when no nitrogen applied over 150 and 225 kg ha-1 with earliness index values of 0.75 and 0.74, respectively. Significantly higher seed cotton yield (1714 kg ha-1) was obtained with 225 kg N ha-1 and was followed by 150 kg N ha-1 (1704 kg ha-1). However, which were comparable with each other and significantly superior over no nitrogen and 75 kg N ha-1 application. The rate of increase in seed cotton yield with application of 75, 150 and 225 kg ha-1 over no nitrogen application was 54%, 74% and 75%, respectively. It can be concluded that, higher seed cotton yield with higher B:C ratio can be obtained with application of nitrogen at 150 kg ha-1 in Bt cotton in alfisols of South Telangana Zone.