增密减氮提高夏玉米产量和氮素利用效率

  【目的】  适宜密植是获得高产的关键栽培因子，氮肥高效施用是农业绿色可持续发展的重要环节。探讨不同密度和施氮量组合对夏玉米产量及氮素吸收利用的影响，以期为夏玉米的高产高效栽培提供理论与技术支撑。  【方法】  本研究以‘江玉877’为供试品种，在江苏省宿迁市、盐城市和扬州市3个试验点进行试验，设置60000株/hm2 (D1)、82500株/hm2 (D2) 2个种植密度及不施氮 (N0)、常规肥N 300 kg/hm2 (N1)、常规肥N 225 kg/hm2 (N2)、缓释肥一次性基施N 225 kg/hm2 (N3) 4个施氮方式。研究夏玉米产量、干物质及氮素积累与分配、氮素利用率对不同密度和施氮方式组合的响应。  【结果】  不同种植密度条件下，4个施氮方式对夏玉米产量及氮素吸收利用具有显著影响。相同施氮量下，2个种植密度单株籽粒产量表现为D2 < D1，但群体产量表现为D2 > D1。D1种植密度下，N1和N3的平均群体产量比N2分别提高11.3%和10.9%，D2种植密度下比N2分别提高7.4%和9.0%，且相同密度条件下N1和N3的群体产量差异不显著。宿迁点D2N3的群体产量 (9214 kg/hm2) 在所有处理中最高。群体氮素积累量和转运量D2高于D1。D1种植密度下，N3和N1处理的群体干物质和氮素积累总量差异不显著，均显著高于N2处理；D2种植密度下N3处理的群体干物质积累总量显著高于N1处理，群体氮素积累总量差异不显著。各施氮处理的玉米收益在D2种植密度下均显著高于D1种植密度下，D2N3组合在所有处理中收益最高。  【结论】  综合3个试验点产量与氮素吸收利用的结果，在82500 株/hm2种植密度下结合缓释肥N 225 kg/hm2一次性基施，可协同提高江苏省夏玉米产量和氮素利用率，同时降低生产成本，提高玉米种植收益。

Increasing planting density and decreasing nitrogen rate increase yield and nitrogen use efficiency of summer maize

  【Objectives】  Efficient and reasonable application of nitrogen (N) is vital for high yield and green development of agriculture. Suitable plant density and N application rate in summer maize production were studied to provide theorical and technical support of high-productivity and high-efficiency cultivation in summer maize.  【Methods】  Field experiments were conducted in Suqian, Yancheng, and Yangzhou, Jiangsu Province, using maize cultivar of Jiangyu 877 as the tested material. The treatments including two planting densities of 60000 plants/hm2 (D1) and 82500 plants/hm2 (D2), and four N modes of zero N (N0), N 300 kg/hm2 of conventional urea (N1), N 225 kg/hm2 of conventional urea (N2), and N 225 kg/hm2 of slow-release fertilizer (N3). The yield, accumulation and distribution of dry matter and N, and N use efficiency in response to interactions of plant densities and N modes were investigated.  【Results】  Planting densities and N rates significantly affect the yield and N absorption and utilization of summer maize. At the same N rate, single plant yield was higher at D1 than that at D2, while the population yield was higher at D2. In comparison with N2, the average population yields of N1 and N3 were increased by 11.3% and 10.9% under D1, and by 7.4% and 9.0% under D2, respectively. The population yields of N1 and N3 were similar under D1 and D2. The population yield of D2N3 in Suqian achieved 9214 kg/hm2, which was the highest among all treatments. The N accumulation and translocation for population were higher at D2 than those at D1. The total accumulation of dry matter and N of N3 at D1 were similar to those of N1, and both were higher than those of N2. At D2, the total dry matter accumulation in N3 was higher than that in N1, but N accumulation of N3 was similar to that of N1. The profit of different N treatments under D2 was higher than that under D1, and D2N3 got the highest profit among all the treatments.   【Conclusions】  Based on the yield and nitrogen absorption and utilization in the three sites, plant density of 82500 plants/hm2 with slow-released fertilizer of N 225 kg/hm2 can improve the grain yield and N use efficiency, reduce the production cost, and increase profit of summer maize in Jiangsu Province.