中文摘要：

以沿黄常规粳稻品种郑稻19和郑稻20为材料,设置8个氮肥施用水平,即整个生育期不施用氮肥和整个生育期施氮肥（折合纯氮）180、210、240、270、300、330、360 kg/hm2,分析不同氮肥水平对其产量及根系形态、生理特性的影响,以期为水稻的高产高效栽培提供理论依据。结果表明,郑稻19和郑稻20的地上部干质量随生育进程的推进增加,而根系体积、根干质量、根系氧化力、根系吲哚乙酸含量、根系玉米素＋玉米素核苷含量、根系总吸收表面积和活跃吸收表面积则均随生育进程的推进先增加后降低。2个水稻品种的根系体积、根干质量、地上部干质量和根系总吸收表面积在分蘖中期、穗分化始期、抽穗期和成熟期均随施氮量的增加而增加;根系氧化力、吲哚乙酸含量、玉米素＋玉米素核苷含量和活跃吸收表面积在分蘖中期和穗分化始期均随施氮量的增加而增加,而在抽穗期和成熟期均随施氮量的增加先增加后降低,在施氮量为270 kg/hm2时最高。郑稻19和郑稻20的产量均随施氮量的增加先显著增加后显著降低,在施氮量为270 kg/hm2时最高,分别为9.35 t/hm2和8.79 t/hm2,显著高于其他施氮量处理;氮肥农学利用率总体上均随施氮量的增加先显著增加后显著降低,在施氮量为270 kg/hm2时最高,分别为17.0 kg/kg和14.9 kg/kg,显著高于其他处理;氮肥偏生产力则均随施氮量增加而显著降低。综上,在施氮量为270 kg/hm2时,郑稻19和郑稻20的根系形态、生理特性最佳,产量和氮肥农学利用率最高,且品种间比较,郑稻19优于郑稻20。

英文摘要：

A field experiment was conducted to reveal the effects of nitrogen（ N） application rate（0,180,210,240,270,300,330,360 kg/ha） on grain yield and root morphological and physiological characteristics of conventional japonica rice varieties Zhengdao 19 and Zhengdao 20 in region along the Yellow River. The aim of this experiment was to provide the theoretical basis for high-yield and highefficiency cultivation of rice. The results showed that shoot dry weight of Zhengdao 19 and Zhengdao 20 increased with the growth process,the root volume,dry weight,oxidation activity,indole-3-acetic acid（IAA） content,zeatin ＋ zeatin riboside（Z ＋ ZR） content,total absorption area and active absorption area increased first and then decreased with the growth process. The root volume,root dry weight,shoot dry weight and total root absorption area of two rice varieties increased with the increase of N application rate at the middle tillering stage,panicle initiation stage,heading stage and maturity stage; root oxidation activity,IAA content,Z ＋ ZR content and active absorption area increased with the increase of N application rate at the mid-tillering stage and panicle initiation stage,while increased first and then decreased with the increase of N application rate at the heading stage and maturity stage,which all were the highest when the N application rate was 270 kg/ha. The yield of Zhengdao 19 and Zhengdao 20 increased first and then decreased significantly with the increase of N application rate from 0 to 360 kg/ha,the highest yields of Zhengdao 19 and Zhengdao 20 were 9. 35 t/ha and 8. 79 t/ha when the N application rate was 270 kg/ha respectively,which was significantly higher than those of other nitrogen treatments.The agronomic N use efficiency increased first and then decreased significantly with the increase of N application rate,the highest values of Zhengdao 19 and Zhengdao 20 were 17. 0 kg/kg and 14. 9 kg/kg when the N application rate was 270 kg/ha respectively,which was significantly higher than those