Impacts of regulated deficit irrigation on yield, quality and water use efficiency of Arabica coffee under different shading levels in dry and hot regions of southwest China

The yield and quality of Arabica coffee (Coffea arabica) cannot be guaranteed due to irrational irrigation and light management in dry and hot regions of southwest China. The objective of this study was to obtain rational irrigation and shading mode for efficient light and water use, suitable yield and high nutritional quality of Arabica coffee. Taking full irrigation (FI) as the control, the effects of deficit irrigation (DI) (DI75 and DI50, 75 and 50% of full irrigation amount, respectively) on photosynthesis, yield, nutritional quality and water use efficiency (WUE) were investigated under four shading levels (Sh0 no shading, Sh30, Sh45 and Sh60, 30, 45 and 60% shading, respectively) using the field experiments, and a comprehensive benefit assessment model of yield, nutritional quality and WUE was established under different irrigation and shading treatments. Results indicated that DI75 increased leaf apparent radiation use efficiency and the contents of crude fat and chlorogenic acid in dry bean if compared to FI. In comparison with Sh0, Sh30 enhanced dry bean yield, WUE and the contents of total sugar and chlorogenic acid in dry bean. Compared with FISh0 (CK), DI75Sh30 raised dry bean yield, WUE, and the contents of total sugar, protein, crude fat and chlorogenic acid, but reduced the caffeine content. Principal component analysis showed that DI75Sh30 had optimal comprehensive nutritional quality, and TOPSIS method indicated that DI75Sh30 had the optimal comprehensive benefit, showing that our results can provide scientific basis for rational irrigation and light management of Arabica coffee in dry and hot regions.