Projected long-term climate change impacts on rainfed durum wheat production and sustainable adaptation strategies

The impact of climate change on durum wheat (Triticum durum) production is a great concern for future food security in Tunisia. However, whether the current rainfed wheat system can adapt to future climate change is still unclear. Thus, a field and modelling study was conducted using the AquaCrop model and a set of simulated climate data from the Med-CORDEX initiative to analyse the effects of climate change on the environment, production, and water productivity (WP) of wheat under two representative concentration pathways (RCP 4.5 and RCP 8.5) during 2040-2050 and 2080-2090, as well as to determine the best sowing date. Results showed that in comparison with the base line period (BL) the average temperature increased by +4 °C, precipitation decreased −37%, crop cycle duration declined by ∼5 d/decade, reference evapotranspiration diminished to reach 511 mm, irrigation requirements rose to 736 mm, years requiring irrigation increasing from 3 (BL) to 9 and yield gap augmented to reach 55% by the end of the 21st century. Under the RCP 8.5 scenario, optimum sowing dates shifted from mid-September to mid-November for BL to mid-December by the end of the 21st century. Despite delaying the sowing date, the harvest losses remain important (yield gap of 45-55% under the RCP 8.5 scenario), requiring further adaptation strategies. The present study recommends developing a proper mitigation planning policy to ensure the country's resilience and sustainability of durum wheat production.