【摘要】 为探究2个氮效率不同的水稻品种在减氮条件下对产量、氮素吸收利用及根系性状的响应差异，本研究开展了每穴苗数、氮肥施用量、氮肥与密度互作、施氮比例等4个试验，分析氮高效水稻高产的技术路径及其配套生产技术。结果表明，1)在不施肥及各种中低氮施用水平下，氮高效水稻均比氮低效水稻具有显著的高产潜力，平均增产25.28%。在减氮25%情况下，水稻产量比江苏省近五年平均产量高16.63%;1 hm~2 3.15×10~5穴、每穴三苗、前后肥6∶4处理的产量最高，高产的原因是其每穗粒数、千粒重及结实率比氮低效水稻均具有明显的优势。2)氮高效水稻叶面积系数、库容量和生物产量均显著高于氮低效水稻。3)各施氮处理下，氮高效水稻抽穗期和成熟期吸氮量、氮肥利用率对比氮低效水稻具有明显的优势。4)氮高效水稻每株不定根数、单株不定根总长、单株不定根总粗度、单株根干重、总吸收面积、活跃吸收面积和根系活力等指标均显著高于氮低效水稻。综上，就产量和氮肥利用率而言，氮高效水稻具有明显的优势。在适宜密度的条件下，减氮25%时水稻产量明显高于江苏省近五年平均产量水平。根量发达、根系活力强、源库性状优化、物质生产量大、吸氮能力强是氮高效水稻高产高效的主要原因。更多还原

【Abstract】 To investigate the differences in grain yield,nitrogen(N) uptake and utilization,and root traits between two rice varieties differing in nitrogen use efficiency(NUE) under reduced-N conditions,four experiments were conducted.The experiments examined the effects of the number of seedlings per hill,N application rate,the interaction between N application and planting density,and the ratio of basal to topdressing N application to identify the technical pathways and supporting cultivation practices for achieving high yield in N-efficient rice variety.Results indicated that the N-efficient rice variety demonstrated significantly higher yield potential than the N-inefficient rice variety under both zero-N and various medium-to-low N application levels,with an average yield increase of 25.28%.Under 25% N reduction condition,its grain yield exceeded the five-year average yield in Jiangsu province by 16.63%.The treatment of 3.15×105hills per hectare,three seedlings per hill,and a 6:4 basal to topdressing ratio achieved the highest yield,mainly due to higher grains per panicle,1 000-grain weight,and seed setting rate.The N-efficient rice variety also exhibited significantly higher leaf area index(LAI),sink capacity,and biological yield.Across all N treatments,the N-efficient rice variety exhibited clear advantages in N accumulation and NUE at heading stage and maturation stage.The N-efficient rice variety also displayed significantly superior root traits compared with N-inefficient rice variety,including a greater number of adventitious roots per plant,longer total root length,thicker roots,higher root dry weight,larger total and active root absorption areas.In conclusion,the N-efficient rice variety showed clear advantages in both grain yield and nitrogen use efficiency.Under an appropriate planting density,a 25% reduction in N application still resulted in a yield significantly higher than the provincial average over the past five years.The high yield and efficiency of the N-efficient rice is primarily attributed to its well-developed root system,strong root activity,optimized source-sink characteristics,high biomass production,and strong nitrogen uptake capacity.更多还原