Long-term response of rainfed sorghum to diverse growing environments and optimal sowing window at Coimbatore

Abstract

Rainfed sorghum production is profoundly vulnerable to climate variability. Sowing the crop at an appropriate time could be one of the most crucial climate-resilient options to improve the yield. The well-calibrated and validated CERES-Sorghum model was employed to study the rainfed sorghum response to varied environments over the long term (1983–2021) and to determine the optimum sowing window at Coimbatore, Tamil Nadu. The CERES-Sorghum model was used for automatic-planting with a different minimum threshold of 50,60,70 and 80 percent soil water content at 15 cm soil depth under various sowing windows from 1stSeptember to 13th October at a 7-day interval. The model results of automatic planting event indicated the best performance of 1st September sowing window at 50 percent soil water content over 39 years under semi-arid environment. The temperature rise of 1˚C exhibited no significant influence on sorghum grain yields at all sowing windows and a slight reduction in yield was observed at an elevated 2˚C temperature. A further rise in temperature reduced the yield drastically on September month sowings. Across the sowing window, first week sowing window (1st to 7th September) yield was higher under current climatic conditions. The yield of 1st September sowing window remained higher in the elevated temperature conditions as well as in both deficit and excess rainfall conditions than other sowings. In current and future climatic conditions, 1st September sowing window would be the best sowing time to mitigate climate risk in rainfed sorghum.