氮锌配施对不同玉米品种灌浆期生理特性和籽粒氮锌含量的影响

提高粮食作物中可食部分的锌生物有效性是解决人体缺锌的重要措施。为研究氮锌肥料施用对玉米籽粒锌营养的影响,本研究以郑单958和谷神玉66为试验材料,在大田条件下研究3个氮水平(90、180 和225 kg N·hm^-2)和2个喷锌处理(0和4.5 kg·hm^-2 ZnSO₄·7H₂O)下玉米籽粒产量和氮锌含量以及灌浆期叶片生理特性的变化。结果表明,吐丝后,与施氮量90 kg·hm^-2处理相比,施氮量180和225 kg·hm^-2处理提高了吐丝后穗位叶SPAD值及硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、碳酸酐酶(CA)、超氧化物歧化酶(SOD)活性和灌浆后期PSⅡ综合性能指数(PI),降低了丙二醛(MDA)含量。施锌能提高吐丝后穗位叶CA、SOD、过氧化物酶(POD)、过氧化氢酶(CAT)活性和灌浆后期SPAD值和PI,降低MDA含量。2个品种相比,谷神玉66灌浆后期穗位叶SPAD值、叶片初始荧光(F_o)和最大荧光(F_m)较高,而灌浆前期穗位叶PI和吐丝后NR、CA、SOD以及POD活性则以郑单958较高。施氮量为90 kg·hm^-2时,玉米籽粒产量平均为8.55 t·hm^-2,随着施氮量增加,玉米籽粒产量显著提高。籽粒中氮含量以施氮量180 kg·hm^-2时最高,为14.85 g·kg^-1。施氮量90和180 kg·hm^-2时,籽粒锌含量平均为27.2 mg·kg^-1,显著高于施氮量225 kg·hm^-2处理。与不施锌相比,喷锌后玉米籽粒产量未有显著变化,籽粒中氮、锌含量分别增加了11.7%和18.0%。郑单958籽粒产量较谷神玉66提高了3.8%,籽粒氮锌含量则分别减少了11.9%和5.3%。综合来看,施氮量为180 kg N·hm^-2时,与喷施ZnSO₄·7H₂O 4.5 kg·hm^-2 配合施用能够增强玉米灌浆期叶片SPAD和荧光特性,提高氮锌代谢关键酶活性,增强氧自由基清除系统酶活性,减弱膜脂过氧化作用的伤害,促进籽粒中氮、锌的吸收和累积。本研究结果可为玉米生产中优化锌生物强化措施提供理论依据。

Effect of Nitrogen and Zinc Application on the Photosynthetic Characteristics in the Grain Filling Stage and Grain Nitrogen and Zinc Content of Different Maize Varieties

Improving the zinc(Zn) bioavailability of cereal edible part is an effective measure to solve Zn deficiency of human. A field experiment was conducted with ZD958 and GSY66 of maize hybrids. Three nitrogen rates(90, 180 and 225 kg N·hm^-2) and two foliar zinc application(0 and 4.5 kg·hm^-2 ZnSO₄·7H₂O) were set to analyse the variation of the maize grain yield, N and Zn concentration and photosynthetic characteristics of leaf in the grain filling stage of maize, to evaluate the effect of N and Zn fertilizer application on the Zn nutrition of maize grain. The results showed that, compared with N application of 90 kg·hm^-2, N rate with 180 and 225 kg·hm^-2 had the higher leaf SPAD, and NR, GS, SOD, POD and CAT activity after silking, PSⅡ comprehensive performance index(PI) in the later grain filling, and the lower content of MDA after silking. Foliar Zn increased leaf CA, SOD, POD and CAT activity after silking and SPAD, PI in the later grain filling and decreased content of MDA. Between two cultivars, higher leaf SPAD, Fo and Fm in the later grain filling was obtained in GSY66 and higher leaf PI in the early grain filling, NR, CA, SOD and POD activity after silking was found in ZD958. Grain yield was 8.55 t·hm^-2 with N application of 90 kg·hm^-2 and increased with N application increased. The N content with 180 kg·hm^-2 had the highest grain N concentration (14.85 g·kg^-1). Grain Zn concentration was higher in the N application of 90 and 180 kg·hm^-2, averagely 27.2 mg·kg^-1, compared with 225 rate kg·hm^-2. Compared with no Zn application, foliar Zn had no effect on the grain yield, but increased the N and Zn concentration of grain by 11.7% and 18.0%, respectively. Relative to GSY66, ZD958 had improved grain yield by 3.8% but decreased N and Zn concentration by 11.9% and 5.3%, respectively. These results suggested that N application with 180 kg·hm^-2 and foliar ZnSO₄·7H₂O with 4.5 kg·hm^-2 could enhance maize leaf SPAD and fluorescence parameter, and increase the enzyme activity of nitrogen and zinc metabolize and oxygen free radical scavenging system, thus to reduce the damage of membrance lipid peroxidation and promote the absorption and accumulation of N and Zn in the maize grain. The result could provide a theoretical guide for enhancing the Zn biofortification in the maize production.