麦茬高度对机播夏玉米苗期生长及水分利用的影响

【目的】在冬小麦-夏玉米轮作免耕留茬种植体系内，麦茬高度对土壤蓄水保墒能力、夏玉米出苗及生长发育具有重要影响。本研究在冬小麦-夏玉米轮作地区，探求适宜机播夏玉米苗期生长及高产高效的冬小麦留茬高度，为实现农艺栽培措施和农业机械化的高效、有机结合提供理论依据。【方法】试验于2012-2014年在中国农业大学吴桥实验站进行，以郑单958为试验材料，在大田条件下设3个麦茬高度（15 cm、25 cm、35 cm），其余部分随机收粉碎覆盖还田，采用机械化精量播种。通过测定夏玉米出苗率、苗期农艺性状、干物质积累、田间耗水量、产量及构成因素和水分利用效率，比较分析小麦不同留茬高度对夏玉米播种出苗质量、苗期生长发育、产量及水分利用效率的影响。【结果】（1）35 cm麦茬处理能够显著降低播种到拔节期农田耗水量和全生育期农田耗水量，显著增加夏玉米出苗率并提高田间株高整齐度。（2）35 cm麦茬能够促进4叶展期株高和叶片的增长，但茎粗变细，差异均达到显著水平（P＜0.05）。（3）35 cm 麦茬处理下玉米拔节期的茎秆变粗，株高、叶面积指数和单株干物质积累均处于最高水平，其中干物重差异显著。（4）与15 cm和25 cm麦茬高度相比，35 cm麦茬处理下玉米的3年平均籽粒产量分别增加了10.59%和5.31%，产量增加主要是由单位面积粒数的增加引起；3年平均水分利用效率分别提高了21.55%和12.64%（P＜0.05），年际间水分利用效率也具有较大差异，降雨较多的年型，水分利用效率低。【结论】在3个麦茬高度下，35 cm麦茬处理蓄水保墒效果较好，有利于夏玉米苗期生长发育，在增加夏玉米产量和水分利用效率方面效果显著，符合免耕留茬区域农业机械化播种的发展趋势，应用前景广阔。

Effects of Wheat Stubble Height on Growth and Water Use Efficiency of Mechanized Sowing Summer Maize

【Objective】In winter wheat-summer maize rotation system, wheat stubble was retained in field after harvest and maize seeds were sowed directly without tillage. Standing stubble height affected light penetration and straw residue amounts, which might affect soil water humidity, maize emergence rate and crop development. This research aimed at finding out a proper standing stubble height to increase water use efficiency and emergence rate, and finally to improve grain yield of summer maize.【Method】Summer maize hybrid Zhengdan958 was used as experimental materials. A 3yr (2012-2014) field experiment was conducted in order to explore a proper stubble height at Wuqiao Experimental Station of China Agricultural University, Hebei Province. Three stubble height treatments were compared: 35, 25, and 15 cm. The emergence rate, crop growth parameters, dry matter accumulation, soil water consumption and water use efficiency of summer maize were measured in this research. 【Result】From sowing to jointing stage, the treatment with stubble height 35 cm significantly reduced soil water consumption amount, while emergence rate and plant height uniformity of summer maize were both increased significantly. Plant height and leaf area of 35 cm stubble were both greater while stems were thinner than under shorter stubble height treatments at 4-leaf stage. At jointing stage, plant height, stem diameter, leaf area and dry biomass of 35 cm stubble height were all the greatest among treatments. Summer maize yield of 35 cm stubble height was 10.59% and 5.31% higher than that of 25 and 15 cm. Increased grain yields were the result of the increase of kernels number per unit area. Moreover, water use efficiency was 21.55% and 12.64% greater than that of 25 and 15 cm, respectively. The water use efficiency showed large differences between annual precipitations. During the years with more rainfall, water use efficiency was low.【Conclusion】Wheat stubble height of 35 cm was helpful to maize seedling growth and strongly improved the grain yield and water use efficiency of summer maize.