氮高效水稻实现减氮、增产和高氮肥利用率的途径与原因分析OA

To investigate the differences in grain yield,nitrogen(N)uptake and utilization,and root traits between two rice varieties differing in nitrogen use efficien-cy(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 3.15×105 hills 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.