Effects of regulated deficit irrigation on yield and water productivity of chili pepper (Capsicum annuum L.) in the arid environment of Northwest China

Due to the scarcity of water resources in Northwest China, the use of deficit irrigation scheduling is beneficial for sustainable agricultural development. Therefore, a 2-year field experiment was performed to investigate the effects of regulated deficit irrigation (RDI) on the yield and water productivity (WP) of drip-irrigated chili pepper plants in a typical arid environment of Northwest China. The results indicate that RDI strategies reduced actual crop evapotranspiration by 2-27%. Crop coefficients for chili pepper averaged 0.85, 1.09 and 0.84 for the development, middle and late stages, respectively. The highest yield occurred under full irrigation. The largest yield reduction (13-20%) was recorded when water deficit occurred during the middle stage. Fifty percent water deficit reduced yields more than 25% water deficit did. The highest irrigation water productivity and WP were achieved when water deficit occurred during the late stage. RDI may improve fruit quality by increasing the content of total soluble solids of the fresh fruit. In conclusion, full irrigation is recommended first for achieving the highest yield, and a water deficit of 25-50% during the late stage is also recommended if considering economic benefits and WP in the study region.