Diagnosis of the rainfall-wheat yield relationship in the current and future climate change conditions in Eastern Algeria

Future projections indicate that rain-fed agriculture in North Africa is among the most vulnerable in the world in the context of future climate change. This article aims to diagnose the relationship between rainfall and wheat yield in both current and future climatic situations in a semi arid agro-climatic conditions represented by the region of Bordj Bou Arreridj. For the current situation, we used 15 years (1995–2009) of recorded rainfall and durum wheat yield series. Future rainfall projections (2071–2100) were generated by the MED-CORDEX climate model version CCLM4-8-19 under RCP 6.0 scenario. Simulated data over the observed period and that of the future on the maximum evapotranspiration (ETM) of durum wheat and the water deficit (WD) accumulated over the cycle as well as future yields are obtained using a simple agro meteorological crop simulation model, previously validated. In both current and future situations, precipitations, ETM, WD and yields data are first analyzed, then yields are related by regression to three components of rainfall: annual rainfall, cumulative rainfall over the crop cycle (November–June) and cumulative rainfall during spring (March–May). In the observed climate, annual precipitation averages 382.3 ± 96.3 mm, cumulative rainfall over the crop cycle (November–June) averages 278.3 mm and cumulative rainfall during spring is 101.9 mm. These last decrease to 303.7 ± 99.4, 232.3 and 83.3 mm in the future situation. Observed yields (1995–2009) averages1.9 ± 0.64 q/ha in the observed situation and decrease to 15.5 ± 0.54 q/ha in future climate. ETM are low and WD values are high in the current climate, with a worsening of the situation in the future climate, particularly during spring. The correlation between yields and précitations is always positive in both weather conditions, but the best R2 are 0.65 and 0.82 and concern spring rains. In semi-arid regions, cumulative rainfall towards the end of the growing season is currently impacting the grain yield of durum wheat and will become more decisive in the context of future climate change