Trends Analysis of Reference Evapotranspiration and Crop Water Productivity of Last 3 Decades in Different Agroclimatic Zones of Punjab by Using Cropwat 8.0 model

This study investigated long-term variability in grain yield and crop water productivity (CWP) for six major crops in Punjab, India, over three decades and three key locations. Results showed significant spatial variability such as Ludhiana consistently achieved high yields for rice, wheat and barley, while Amritsar recorded higher yields for maize, mustard and sugarcane. Analysis of water use efficiency revealed that CWP generally improved in later decades, a trend often associated with adjusted sowing and transplanting dates. An inverse relationship between crop evapotranspiration (ETc) and CWP was observed for most crops and locations which suggests that higher water use corresponded with lower water productivity. Exceptions included rice in Ludhiana, where CWP increased with ETc, and maize in Amritsar and Ludhiana which exhibited a positive correlation. The findings indicate that historical yield gains have primarily driven improvements in water productivity, which emphasizes the imperative for location and crop-specific management strategies like optimized sowing dates to enhance water-use efficiency.