Productivity of Bt Cotton under Different Levels of Irrigation and Nitrogen in Alfisols

Aims: To determine the optimum irrigation schedule and nitrogen level for Bt cotton in alfisols in Southern Telangana.Study Design: Split plot design.Place and Duration of Study: ARI, Rajendranagar, Hyderabad during kharif 2014.Methodology: The experiment was laid out with three irrigation schedules (I1- 0.8 IW/CPE, I2 - 0.4 IW/CPE and I3 - Rainfed) as main plots and four nitrogen levels (N1- 0 kg ha-1, N2 - 75 kg ha-1, N3 - 150 kg ha-1 and N4 - 225 kg ha-1) as sub plot treatments replicated thrice. Treatments imposed as per the schedule and data recorded on yield, yield attributes, nitrogen uptake by adopting standard proceduresResults: Irrigation at 0.8 IW/CPE recorded significantly higher plant height (79 cm), drymatter at first picking (195 g plant-1), bolls plant-1 (16), seed cotton yield (1435 kg ha-1), lint yield (541 kg ha-1), stalk yield (2057 kg ha-1) and nitrogen uptake (63 kg ha-1) and was not differed significantly with 0.4 IW/CPE and these were significantly superior to rainfed cotton. Among nitrogen levels, significantly higher plant height (90 cm), drymatter at first picking (214 g plant-1) stage, days to reach boll development (90) stage, bolls plant-1 (15), boll weight (5.3 g), seed index (9.9 g), seed cotton yield (1435 kg ha-1), lint yield (547 kg ha -1) and stalk yield (2214 kg ha -1) were found with application of nitrogen at 225 kg ha-1 was comparable with 150 kg N ha-1 and were significantly superior over lower levels of nitrogen application. The substantial increase in yield and yield attributes might be due to favorable effect on growth attributes like plant height, increased bolls plant-1, drymatter accumulation plant-1 and its subsequent translocation towards sink improved the seed cotton yield.Conclusion: It can be concluded that, higher seed cotton yield can be obtained with the irrigation scheduled at 0.4 IW/CPE and application of nitrogen at 150 kg ha-1 in Bt cotton grown in alfisols.