播期和水氮互作对滴灌施肥春玉米生长和水氮利用的影响

  【目的】  河西地区石羊河流域的农业生产中水资源短缺，光热资源利用率和水肥利用效率低。通过调整播期协调光热资源与水肥供应，研究提高春玉米生长及水肥利用效率的可能性。  【方法】  大田滴灌试验于2018年在甘肃省中国农业大学石羊河流域农业与生态节水试验站进行。设置3个播种日期，即4月10日 (S₁)、4月20日 (S₂)、4月30日 (S₃)；2个灌水量水平，即80% ET_c (I₈₀)、100% ET_c (I₁₀₀) (ET_c为作物蒸发蒸腾量)；4个施氮量水平，即N 0、120、180、240 kg/hm2，分别表示为N₀、N₁₂₀、N₁₈₀、N₂₄₀。在玉米生长关键期，测定植株生长状况和水分利用指标，收获期测产。  【结果】  播期对春玉米各生育阶段的持续时间影响显著，生育期天数随着播期的推迟呈缩减趋势，合理播期应避免灌浆期的高温辐射和降雨量过多。除耗水量外，施氮量对其它各指标影响显著。叶面积指数、干物质积累量和产量均随灌水量增加而增加，随施氮量增加而上升，产量随播期的推迟而减少。S₁I₁₀₀N₁₈₀处理产量最大，为16830 kg/hm2，比S₂I₁₀₀N₂₄₀处理增产7.35%、节肥14.29%，比S₃I₁₀₀N₁₈₀处理增产12.55%。水分利用效率随施氮量增大而增加，随灌水量增大而升高。S₁I₁₀₀N₁₈₀处理水分利用效率为3.1 kg/m3，比S₁I₈₀N₂₄₀处理高12.32%。氮肥偏生产力随施氮量增大而减小，S₁I₁₀₀N₁₈₀处理氮肥偏生产力为93.5 kg/kg，比S₁I₁₀₀N₁₂₀处理降低4.9%，但增产42.65%。  【结论】  综合产量和节水节肥因素，在本试验条件下适时早播 (4月10日) 有助于充分发挥水肥资源的潜力。在早播和充分灌水条件下，施用较低的氮肥量 (N 180 kg/hm2) 即可获得最高的产量。

Effects of sowing date and water-nitrogen interaction on the growth and water and nitrogen utilization of spring maize under drip fertigation

  【Objectives】  The Shiyang River basin of Hexi region is short in water recourses and rich in light and heat resources, the utilization efficiency of water and fertilizer in agricultural production is generally low. We studied the possibility of coordinating the natural and water and nutrient resources through regulating the sowing date of maize.  【Methods】  A field experiment with complete block design was carried out in the Shiyang River Basin Agricultural and Ecological Water-Saving Experimental Station of China Agricultural University. The treatments were composed of three sowing dates, namely S₁: (2018–04–10), S₂ (2018–04–20), S₃ (2018–04–30), two irrigation rates, i.e. 80% ET_c (I₈₀), 100% ET_c (I₁₀₀) (ET_c was the crop evapotranspiration), and four nitrogen application levels, i.e. N₀, N₁₂₀ (120 kg/hm2), N₁₈₀ (180 kg/hm2), N₂₄₀ (240 kg/hm2). The nutrient uptake and water use efficiency of maize were measured at the key growing stages, and the yield was recorded at harvest.  【Results】  Sowing date had a significant effect on the duration of each growth stage of spring maize, and the number of growing days decreased with the delay of sowing date. Nitrogen application had a significant effect on indexes except water consumption. Leaf area index, dry matter accumulation and grain yield all increased with the increase of irrigation water and N application rate, and decreased with the delay of sowing date. The yield in treatment S₁I₁₀₀N₁₈₀ was the highest (16830 kg/hm2) and was 7.35% higher than that in S₂I₁₀₀N₂₄₀ (15678 kg/hm2) and 12.55% higher than that in S₃I₁₀₀N₁₈₀ (14954 kg/hm2). The water use efficiency (WUE) increased with the amount of N fertilizer and irrigation. The WUE in treatment S₁I₁₀₀N₁₈₀ was 3.1 kg/m3, which was 12.32% higher than that in S₁I₈₀N₂₄₀. The partial productivity of nitrogen fertilizer (PPNF) decreased with the increase of N fertilizer rate. The PPNF in treatment S₁I₁₀₀N₁₈₀ was 93.5 kg/kg, which was 4.9% lower than that in S₁I₁₀₀N₁₂₀, but the yield was increased by 42.65%.  【Conclusions】  Comprehensively considering the yield and water and fertilizer utilization efficiencies, early sowing (April 10) is good for full use of fertilizer and water resources. Under early sowing and fully irrigation, the highest yield of spring maize can be achieved at lower N rate of 180 kg/hm2. The combination has obvious fertilizer-saving effect in spring maize production under the tested conditions.