施氮量和种植密度一直以来是玉米获得高产的两大主要因素。目前，氮肥投入过量和种植密度低是我国玉米主产区普遍存在的主要生产问题，因此，合理增密和减氮是协同提高东北春玉米产量和氮肥高效利用的重要途径。为此，以国审玉米新品种辽单575为供试材料，采用随机试验设计，设3个种植密度（6.0、6.75和7.5万株/hm2），3个施氮量（135、180和225 kg/hm2）。结果表明，与D6.00相比，D6.75、D7.50条件下玉米群体干物质积累量显著升高，2017年提高了14.9%、17.6%，2018年提高了0.4%、11.3%。与N135相比，N180、N225的氮素积累量较高，分别提高了0.2%、0.9%（2017年）；9.3%、8.1%（2018年）。2年间玉米籽粒最高产量均在D6.75和N225处理下获得。2017年D6.75N225和2018年D6.75N180、D6.75N225处理的玉米产量显著高于其他处理，密度和氮肥的互作效应对玉米产量的影响显著，说明适量增密减氮是协同提高玉米产量的重要途径。2年间收获指数、氮收获指数和氮肥偏生产力最高值均在D6.75处理下获得。因此，推荐辽单575适宜的种植密度从常规的密度增加到6.75万株/hm2，施氮量第一年为225 kg/hm2，第二年减少为180 kg/hm2，可实现减氮增密增产的目标。
英文摘要:
Nitrogen rate and planting density have been the two main factors for high maize yield. At present, excessive nitrogen input and low planting density are the main problems in the main maize production areas in China. Therefore, reasonable increased density and nitrogen reduction are important ways to improve the yield and the efficient utilization of nitrogen fertilizer of spring maize in Northeast China. A new maize hybrids released in China, Liaodan575, was used as experiment materials. Three plant densities (60, 67.5 and 75 thousand plants per hectare) and three nitrogen rates (135, 180 and 225 kg/hm2) were designed by random experiment in 2017 and 2018. The results showed that compared with D6.00, D6.75 and D7.50 dry matter accumulation of maize significantly increased by 14.9% and 17.6% in 2017, 0.4% and 11.3% in 2018. Compared with N135, N180 and N225 nitrogen accumulation were higher, increased by 0.2% and 0.9% (in 2017), 9.3% and 8.1% (in 2018), respectively. During the 2017 and 2018, the highest maize yield was obtained under the treatment of D6.75 and N225. The maize yield of D6.75N225 in 2017 as well as D6.75N180 and D6.75N225 in 2018 was significantly higher than that of other treatments, and the interaction effect of planting density and nitrogen application amount significantly affected maize yield, indicated that increased plant density with reduced N rate properly was an important way to synergistic improve maize yield. The highest harvest index, nitrogen harvest index and nitrogen partial productivity were obtained under D6.75 treatment in 2017 and 2018. Therefore, it is recommended for Liaodan575 that suitable planting density should be increased from the conventional density to 67.5 thousand plants per hectare, and the amount of nitrogen application should be 225 kg/hm2 in the first year, and then to 180 kg/hm2 in the next year. It can achieve the goal of reducing nitrogen, increasing density and increasing maize yield.
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