以黄淮海地区主栽玉米品种郑单958(ZD958)、先玉335(XY335)、郑单309(ZD309)、奥玉3111(AY3111)、浚单20(XD20)和迪卡653(DK653)等6个杂交种为试验材料，设0、120(较正常施氮量减少1/2)、160(减氮1/3)、200(减氮1/6)和240(正常施氮量) kg N/hm2等5个施氮水平，在大田条件下研究氮肥减施对夏玉米产量、花后氮素转运、叶片叶绿素荧光和硝酸还原酶NR、谷氨酰胺合成酶GS活性的影响。施氮后玉米产量平均提高20.2%，与正常氮处理相比，减氮1/3和1/6的产量、籽粒氮浓度、收获指数和氮收获指数NHI无显著变化，ZD309和XY335产量和NHI高于其他品种。随施氮量增加，ZD958、XY335和ZD309叶转运量显著增加，茎转运效率无显著变化。与正常氮相比，减氮1/3和1/6穗位叶SPAD无变化，叶绿素最大荧光Fm、综合性能指数PI、NR活性明显增加，各基因型分别以AY3111和XD20叶片SPAD、PI为最高和最低，ZD958、XY335和ZD309的NR和GS活性高于其他品种。在本试验条件下，氮肥减施1/6-1/3，能够保证玉米生育后期氮素供应，维持叶绿素含量、光合速率和氮素代谢酶活性，协调各器官对氮素的吸收和分配，达到高产高效。
英文摘要:
Six major summer maize cultivars, including ZD958, XY335, ZD309, AY3111, XD20 and DK653, were selected as experimental materials, and five N application of 0, 120(reducing 1/2 of normal N rate), 160(reducing 1/3), 200(reducing 1/6) and 240(normal N rate) kg N/hm2 were setup. We compared the grain yield, transformation of N after anthesis, chlorophyll fluorescence characteristics and NR and GS activity of leaf in the grain filling stage. Compared with no nitrogen application, the grain yield with adding N fertilization was increased by 20.0%, but no significant differences were obtained in grain yield, N concentration, HI and NHI among normal N rate, reducing N 1/3 and 1/6. ZD309 and XY335 showed higher yield and NHI than other genotypes. The transformation amount of leaf in ZD958, XY335 and ZD309 were increased with the increase of N application level, but N remobilization efficiency of stem under the adding N treatments had no significant difference among the six cultivars. Higher chlorophyll Fm, PI and NR activity, and similar SPAD of leaf in the grain filling stage were found under the reducing 1/3 and 1/6 normal N, compared with normal N rate treatment. The maximum and minimize SPAD and PI of leaf after anthesis were AY311 and XD20, respectively. NR and GS activity of leaf in ZD958, XY335 and ZD309 were significantly higher than other three genotypes. We initially consider that reducing normal N rate of 1/6-1/3 could supply adequate N and maintain the chlorophyll content, photosynthetic rate and enzymatic activity of N metabolism of leaf, harmonize the absorption and distribution of N in different organs in the later growth stage of summer maize, therefore resulting in higher-yielding and N utilization efficiency in the maize productions.
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