不同氮效率玉米品种灌浆期氮素转运特性对氮素形态的响应
大田条件下开展2年定位试验，研究不同氮效率玉米品种登海605（DH）和鲁单981（LD）的产量、氮素吸收和氮素利用效率对氮素形态的响应及其生理机制。结果表明，在2015年和2016年，与LD相比，DH的平均产量分别提高17.2%和20.3%，成熟期植株氮素积累量提高8.5%和10.3%，氮素利用效率提高6.7%和8.5%，氮肥偏生产力提高17.2%和20.3%，而且不受年份（除植株氮素积累量）、氮素形态及其交互作用的影响。两品种子粒氮浓度第一年无显著差异，第二年LD显著高于DH并且不受氮素形态影响。从吐丝后35天到成熟期，DH相对绿叶面积缓慢下降，保绿度为73%，而品种LD相对绿叶面积迅速下降，保绿度仅为48%。品种DH在子粒灌浆期内具有较高的SOD尤其是CAT保护酶的活性，在吐丝后40天具有较低MDA含量，并且DH的NR活性尤其是可溶性蛋白含量在吐丝后均高于LD，表现出较强的氮素吸收和同化能力。从吐丝期到成熟期，两年的花后吸氮量均表现为DH显著高于LD，平均比LD高38.8 kg/hm2 和30.8 kg/hm2。 相反，LD的营养器官氮转移量比DH分别高25.8 kg/hm2 和21.8 kg/hm2，氮素转移效率比DH高10.1～12.1个百分点。结果表明正常施氮条件下，品种LD为低产氮低效品种，品种DH为高产氮高效品种，主要表现为花后具有较高的抗氧化能力，延缓叶片衰老，维持花后较高的氮代谢酶活性，保证花后较强的氮素吸收和同化能力，获得高产同时引起子粒氮浓度下降。
英文摘要:
Two-year filed experiment was conducted to investigate the effects of different N forms on the grain yield, shoot N accumulation and N utilization efficiency of maize cultivar Denghai605 (DH) and Ludeng981 (LD) with contrasting N efficiencies and the related physiological mechanisms. Results showed that in 2015 and 2016, compared with LD, the average yield of DH was increased by 17.2% and 20.3%, the shoot N accumulation at maturity increased by 8.5% and 10.3, N use efficiency increased by 6.7% and 8.5%, and the yield per unit fertilizer N increased by 17.2% and 20.3%, respectively. The years, N forms and their interactions had no significant effects on the above parameters with an exception of a significant effect of the year on the shoot N accumulation at maturity. The grain N concentration was not significantly different between the two cultivars in the first year, but the grain N concentration of LD was significantly higher than that of DH in the second year, which was not affected by different N forms. From 35 days after silking to maturity, relative green leaf area of DH reduced slowly with being 73% of stay-green degree while that of LD decreased quickly with being only 48% of stay-green degree. During the grain-filling period, DH had higher key antioxidant enzymes such as SOD, especially the CAT activities while with lower MDA content at 40 DAS. Meanwhile, compared with LD, DH had slightly higher NR activity and significantly higher soluble protein content in ear leaves, showing a higher ability for N uptake and assimilation. From anthesis to maturity, the amounts of post-silking N uptake of DH in two years were 38.8 kg/hm2 and 30.8 kg/hm2 higher than LD, respectively. On the contrary, the amounts of vegetative N remobilization and N remobilization efficiency of LD were 25.8 kg/hm2 and 21.8 kg/hm2 and 10.1～12.1 percentage points higher than DH, respectively. These results suggested that at normal N application rate (220 kg N/hm2), LD with both lower yield and N efficiency, DH with both higher yield and N efficiency, showed higher antioxidative ability to delay senescence, to maintain higher activities of key enzymes related with N metabolism, to improve N uptake and assimilation, and finally to gain higher yield but to decrease grain N concentration.
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