Trends in Temperature and Rainfall Variability and Their Relationship with Rice and Wheat Yields across Agro-Climatic Zones of Uttar Pradesh, India (1993–2023)

Abstract

Climate variability, particularly changes in temperature and rainfall, can substantially influence the productivity of major food crops such as rice and wheat. Understanding long-term climate–yield relationships across the diverse agro-climatic zones of Uttar Pradesh is important for assessing spatial differences in crop responses to changing climatic conditions. This study examined long-term variability and trends in temperature and rainfall and their relationships with rice and wheat yields across nine agro-climatic zones of Uttar Pradesh, India. Annual climatic data for 1993–2023 and crop-yield data for 1998–2023 were analysed using descriptive statistics, the Mann–Kendall trend test, Sen’s slope, and Pearson correlation analysis. Maximum temperature generally showed weak, statistically non-significant decreasing trends, whereas minimum temperature displayed mostly weak and non-significant increasing tendencies. Rainfall exhibited substantially greater variability than temperature, with pronounced seasonal differences among districts, although long-term rainfall trends were also statistically non-significant. Correlation analysis showed that maximum temperature was negatively associated with rice and wheat yields across the agro-climatic zones, with the strongest negative relationships observed in Jhansi and Mathura. Rainfall was positively associated with crop yields in most districts, with particularly strong rice-yield correlations in Pilibhit, Jaunpur, and Basti. Minimum temperature generally showed weak positive and non-significant relationships with crop yield, while wind speed had only a minor influence. The findings demonstrate clear spatial variation in climate–yield relationships across Uttar Pradesh, with moisture-related influences more evident in the eastern and Terai areas and stronger temperature-related constraints in the semi-arid districts. These results provide a zone-wise assessment of long-term climatic variability and crop-yield responses across the state.