New pathways and the associated uncertainties for increasing maize water use efficiency under global warming

摘要

ABSTRACT The DSSAT4.7-CERES model was employed to simulate plant-water nexus conditions in the future of Mazandaran province in Iran, using ensemble outputs of various GCMs and emission scenarios with LARS-WG 5.5 in the time period 2010–2100. The results showed during the 21st century, maize water requirement is expected to be reduced by 3.3–14.1. Under climate change scenarios, both negative and positive changes in crop yield are projected, between −37.4 and 36.1, which consequently results in a 5.1–27.2 reduction in water use efficiency (WUE) in the future periods. Deficit irrigation (DI) with 25 reduction in irrigation water depth (DI75) lead to a moderate reduction of 4.3–5.5 in WUE, but WUE was highly reduced under DI55. While early planting may reduce WUEs by 0.4–17, late planting almost resulted in improved WUE, especially under DI75. Less frequent irrigation significantly reduces actual evapotranspiration, which consequently resulted in improved WUE by 0.57– 42.47. In conclusion, the integrated assessment reveals that DI75, with an irrigation interval of 5 days, together with a 20 days delay in cropping date of maize in Mazandaran province, may be considered as an effective adaptation solution, when considering both food and water security.