Abstract: Ridge and furrow planting of rainfall harvesting (RFPRH) is a cultivation technique by covering ridges with plastic films and planting crops in furrows. RFPRH has been extending in the semi-arid areas of Loess Plateau in Northwest China because it can alleviate drought stress by collecting rainfalls from the ridges and promote water use efficiency (WUE) and crop yield. To investigate the optimal quantity of rainfall in RFPRH system, we studied the effects of RFPRH, taking traditional cultivation as the control, on soil water storage, photosynthetic indexes, fluorescence parameters and chlorophyll relative content (SPAD) in functional leaves, and grain yield of summer corn (Zea mays L.) under three simulated rainfall treatments. The rainfall was given 12 times (at 5–15 d interval) in corn growth duration with the total amount of 230, 340, and 440 mm, respectively. In the RFPRH system, the net photosynthetic rate (P_n), stomatal conductance (G_s) and chlorophyll fluorescence parameters (F_m, F_v, F_v/F_m, F_v/F, and qP) were significantly (P<0.05) higher than those in control, and the SPAD value increased by 17.7% and 13.9% in 230 and 340 mm rainfall treatments, respectively. Compared to the control, the instantaneous WUE in leaves increased by 26.9% and 10.1%, and the grain yield by 75.4% and 36.7% under 230 and 340 mm rainfall treatments, respectively. The F_m, F_v/F_m, F_v/F_o, qP, and SPAD value at jointing stage and G_s at heading stage increased significantly (P<0.05), but P_n decreased sharply at heading and booting stages under 440 mm rainfall treatment in RFPRH system. The WUE of the whole growth duration of RFPRH was lower by 13.2% than that of control. The results indicate that the RFPRH system can promote Pn and leaf WUE of corn in arid years, and 440 mm may be the upper limit of rainfall during the whole growth period in the RFPRH system.

Key words: Rainfall simulation, Ridge and furrow planting for rainfall harvesting (RFPRH), Photosynthetic characteristics, Summer corn