覆膜方式和滴灌带布设对春玉米根区土壤水氮均匀度及根冠生长及产量的影响

为探求不同覆膜方式及滴灌带布设对作物产量及收获系数的影响,设置不同滴灌带间距(A1:1 m;A2:0.5 m)与覆膜方式(M1:全覆盖;M2:半膜覆盖),通过2年田间试验研究其对根区土壤水氮分布均匀度(CU_w, CU_N)及春玉米根冠生长及产量的影响。结果表明:膜下滴灌条件下,根区土壤含水率与其分布均匀度具有一致性;高频滴灌施肥虽提高根区土壤NO₃^-含量却降低其分布均匀度,表现出不一致性。提高土壤水、氮分布均匀度未显著影响作物根长密度,但增加地上部叶面积,从而降低作物根冠面积比。相比滴灌带布设,覆膜方式对春玉米产量和收获系数的影响更为显著。低频灌溉条件下,全膜覆盖处理提高春玉米根区土壤水分和NO₃^-含量及均匀度,其作物产量较部分覆膜处理提高37.4%;而高频灌溉下,部分覆膜处理的作物产量较全膜覆盖处理提高7.7%。当根表面积与叶面积之比(RSA/LA)趋于4时,作物产量和收获系数最高,RSA/LA过高或过低均会降低作物产量和收获系数。综合考虑作物产量、收获系数和滴灌带成本,低频灌溉下建议选择A1M1处理,高频充分灌溉条件下建议选择A1M2处理。

The Combined Effects of Plastic Film Mulching and Lateral Layout on Soil Water and Nitrate Distribution Uniformity, Shoot-Root Growth, and Grain Yields of Mulched Drip Irrigated Spring Maize

A 2-year experiment was conducted to investigate the effects of different lateral spacing and mulching methods on soil moisture, soil NO₃^- concentration, soil water spatial distribution uniformity (CU_w), soil NO₃^- spatial distribution uniformity (CU_N), shoot-root growth, grain yield, and harvest index (HI) of spring maize in Hetao Irrigation District. The experiment included two lateral spacing (A1: 1 m; A2: 0.5 m) and two mulching methods (M1: fully mulched; M2: partially mulched). Results showed that soil moisture was consistent with CU_w in root zone, however, the increased soil NO₃^- concentration did not lead to an increased CU_N under high-frequency mulched drip fertilization. The improvement of soil water (and CU_w) and NO₃^- (and CU_N) did not significantly influence crop root length (or weight) density, but it increased leaf area, and finally reduced root-shoot ratio. Compared with laterals layout, mulching methods imposed more effects on crop yield and HI. Under low-frequency irrigation condition, compared with partial mulching, full mulching increased soil moisture and NO₃^- concentration in root zone and resulted in higher crop yields and HI; however, grain yields and HI in full mulching were lower than that in partial mulching under high frequency irrigation condition. In this study, grain yields and HI were the highest when the ratio of root surface area and leaf area (RSA/LA) was equal to 4, the too high or too low RSA/LA reduced crop yield and HI. Based on high grain yield, HI, and low costs of drip taps, A1M2 was recommended under high fertigation frequency, while A1M1 was recommended under low fertigation frequency.