RESUMO
Aims: A study was carried out to find out the optimum sowing time with the validated CROPGRO-Cotton model using DSSAT v 4.7 seasonal analysis tool under rainfed situation at mandal level in Nagarkurnool district of Telangana state, India.Study Design: CROPGRO-Cotton model using DSSAT v 4.7 seasonal analysis tool.Place and Duration of Study: Nagarkurnool district, 2023.Methodology: Cotton production was affected with changing climate in several ways and its impact on rainfed agriculture was higher and influences the Indian economy. The prevailing weather conditions during different phenophases of the crop influences the seed cotton yield. There is a need to optimize the sowing time so that the timing of critical growth stages to minimize stresses and enhance resource utilization. The adjusting of sowing environment proved to be an adaptation management technique for realising higher seed cotton yield.A well calibrated and validated model was used for long term simulations using DSSAT seasonal analysis tool programme with Mallika Bt as test variety for 100 different scenarios (20 mandals × 5 sowing dates) using 32 years historical daily weather data from 1991 to 2022 starting sowing time from 1st June to 1st August at 15 days interval in twenty mandals of the district.Results: The simulation results showed, significantly higher seed cotton yield (1505 kg ha-1) was predicted with crop sown on 1st June followed by 1st July sown crop (1337 kg/ha) which was comparable with 16th June (1324 kg/ha) and significantly differed with delayed sowings of 16th July sown crop (1203 kg/ha) and 1st August sown crop (1192 kg/ha). Among the different mandals of the district, the model simulated higher seed cotton yield (2136-2530 kg/ha) in Amrabad mandal and lower yields in Thimmajipet mandal (596-997 kg/ha) under different sowing environments. Conclusion: Based on simulation scenarios, higher seed cotton yield can be obtained when crop sown between 1st June to 1st July in different mandals of the Nagarkurnool district of Telangana State. The mandals which have less yield potential and realising poor yields by the farmers can be advocated with location specific alternate best management practices to get the higher cotton yield.
RESUMO
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.