氮肥减施对夏玉米花后生理特性的影响

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个杂交种为试材,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 kg/hm2(正常施氮量)共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。结果表明,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、子粒氮浓度、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。减氮1/3和1/6处理穗位叶SPAD值无变化,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叶片SPAD、PI为最高,ZD958、XY335和ZD309的NR和GS活性高于其他品种。

Effects of Reducing Nitrogen Applications on the Physiological Characteristics after Anthesis of Summer Maize

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 kg/ha(normal N rate) were setup. The grain yield, the transformation of N after anthesis, chlorophyll fluorescence characteristics and NR and GS activity of leaf in the grain filling stage were compared. 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 was 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 SPAD and PI of the leaf after anthesis were AY311. NR and GS activities of leaf in ZD958, XY335 and ZD309 were significantly higher than the other three genotypes.