半干旱区沟垄集雨对玉米光合特性及产量的影响

在中国西北黄土高原半干旱区, 沟垄集雨种植(RFPRH)系统被逐步推行, 以改善农田水分状况, 提高作物水分利用效率(WUE), 达到高产稳产的目的。为了探索该种植方式的适宜降雨量, 在人工模拟不同降雨量下, 以传统平作为对照, 研究了沟垄集雨种植对夏玉米土壤水分含量、功能叶片的光合参数、荧光参数和叶绿素相对含量(SPAD)以及籽粒产量的影响。结果表明, 在230 mm和340 mm降雨量下, 集雨处理的净光合速率(P_n)、气孔导度(G_s)、最大荧光(F_m)、可变荧光(F_v)、PS II最大光化学量子产量(F_v/F_m)、PS II的潜在活性(F_v/F_o)和光化学猝灭系数(qP)均较对照显著增加; 叶绿素相对含量(SPAD)分别提高17.7%和13.9%, 叶片瞬时水分利用效率提高26.9%和10.1%, 籽粒产量增加75.4%和36.7%。在440 mm降雨量条件下, 集雨处理的F_m、F_v/F_m、F_v/F_o、qP和SPAD值在拔节期显著增加, G_s在抽雄期显著增加, P_n在抽雄期和孕穗期显著下降, 水分利用效率在全生育期比对照平均低13.2%, 其他各生育时期光合生理特性及籽粒产量与对照相比差异不明显。说明沟垄集雨种植在偏旱的年份, 可显著提高玉米光合效率和叶片水分利用效率, 其全生育期适宜雨量上限可能是440 mm。

Effects of Ridge and Furrow Planting for Rainfall Harvesting on Photosynthetic Characteristics and Yield in Corn in Semi-Arid Regions

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.