Effect of different soil moisture regimes on plant growth and water use efficiency of Sunflower: experimental study and modeling

Background Climate change and increasing demand in non-agricultural sectors profoundly affect the availability and quality of water resources for irrigated agriculture. The FAO AquaCrop simulation model provides a sound theoretical framework to investigate crop yield response to environmental stress. This model has successfully simulated crop growth and yield as influenced by varying soil moisture environments for crops. Integrating crop models that simulate the effects of water on crop yield with targeted experimentation can facilitate the development of irrigation strategies for high yield procurement and improving farm level water management and water use efficiency (WUE) under climatic condition of District Hyderabad, Sindh, Pakistan. Results This study was based on completely randomized block design with three treatments including T 1 (30% soil moisture depletion), T 2 (50% soil moisture depletion) and T 3 (70% soil moisture depletion) with three replicates. In order to determine the crop water requirements under desired treatments, the gypsum blocks were used for computing the daily soil moisture depletion. The result shows that total volume of water applied to crop under T 1, T 2 and T 3 was 9689, 5200 and 2045 m 3 ha −1 , respectively. As a result, the grain yield under T 1, T 2 and T 3 was 13.2, 12.1 and 14.3 t ha −1 , respectively. These results advocate that total yield of crop under T 1 and T 2 was less as compared to T 3. The T 3 gave higher yield and WUE compared than other treatments. On the other hand, results revealed that the simulated sunflower yields showed a good agreement with their measured under T 3. The simulated grain yield was 15.5 t ha −1 , while the measured yield varied from 12.1 to 14.3 t ha −1 . This study suggested that WUE under T 3 was more as compared to T 1 and T 2. The results showed that the T 3 gave the highest crop yield in relation to WUE and optimize yield of sunflower crop under water scarcity. Conclusion The Aquacrop model could very well predict crop yield and WUE at T 3 under experiential region for sunflower production.