International Journal of Environment and Climate Change

Wheat (Triticum aestivum L.) is a major winter cereal in India, and its productivity in warm, arid regions such as middle Gujarat is increasingly threatened by rising temperatures. In Gujarat, the crop area has expanded from 1.2–1.4 to 1.25 million hectares in recent years, producing 4.02 million tonnes—about 40.2 lakh tonnes. Climate change, characterised by long-term shifts in temperature and weather patterns, has emerged as a major challenge to crop production. This study assessed the projected impacts of climate change on wheat thermal duration using observed and RegCM4-4 downscaled climate data (CCCma-CanESM2) under RCP 4.5 and RCP 8.5 for the period 2025–2100. Accumulated growing degree days (AGDD), crop duration, and spatial variability were analysed across four districts (Anand, Ahmedabad, Kheda, Vadodara) for three sowing dates (1, 15, and 30 November). The statistical significance of trends was tested using the non-parametric Mann–Kendall test. Spatial interpolation of AGDD for each sowing date and variety was performed using the Inverse Distance Weighted (IDW) method in QGIS 3.38. Results indicated a consistent reduction in crop duration across all scenarios and sowing dates, with greater declines under RCP 8.5 (2–7 days shorter) compared to RCP 4.5. Early sowing (1 November) maintained the longest growth period, while late sowing (30 November) was most affected due to accelerated maturity from terminal heat. Anand recorded the largest reductions, followed by Ahmedabad, Kheda, and Vadodara. The most pronounced reductions were observed in Anand and Ahmedabad, where crop duration shortened by 6–8 days between the two emission scenarios. In contrast, Kheda and Vadodara showed smaller contractions of about 2–5 days. These findings highlight the need for adaptive strategies, including advancing sowing dates and selecting varieties with higher thermal requirements, to sustain wheat productivity under future warming in middle Gujarat.