中文摘要：

采用田间试验在施氮量为0、60、120、180、240、360、360 kg/hm^27个水平下研究了不同水稻子粒产量、产量构成因子以及氮素吸收和利用的差异.结果表明,水稻品种4007的子粒产量在各个施氮水平下显著高于品种ELIO对氮肥的响应度高.施氮水平显著影响子粒产量构成因子.有效穗数与子粒产量存在显著正相关：ELIO和4007的相关系数（r）分别为0.839＊＊和0.933＊＊,表明有效穗数对水稻子粒产量起着非常重要的作用.本试验条件下,ELIO和4007获得最高产量所需的有效穗数分别为332、561个/m^2;两者的氮素吸收效率在各施氮素水平下差异很小,均随着施氮量的增加而增加,而氮素利用效率均随着施氮量的增加而下降.4007的氮素利用效率在各个施氮水平下显著高于ELIO,较高的氮素收获指数（NHI）是主要原因之一.水稻氮素利用效率与成熟期茎秆、叶片的氮含量显著负相关,说明开花期后植物将吸收的氮素从营养器官有效地转运到子粒中是氮素利用效率高的重要原因之一.

英文摘要：

It is of great importance to identify the effects of nitrogen （N） fertilizer on grain yield and N utilization in rice production in terms of N economy and N ecology. Field experiments were conducted to analyze the various traits of yield components and N uptake and utilization by different rice cuhivars under N application rates of 0, 60, 120, 180, 240, 300, 360 kg/ha. Two cuhivars, ELIO and 4007, with similar agronomic traits were cultivated in the southeast in China in 2003 and 2004. Grain yields of 4007, well responding to N application, were significantly higher than those of ELIO at all N application rates. Yield components were significantly affected by N treatments, among which panicles per square meter had highest correlations with grain yields （0.839＊ ＊ and 0.933 ＊ ＊ for ELIO and 4007, respectively）, suggesting the importance of number of panicles for obtaining high yields. Maximum grain yields were obtained at about 332 and 561 panicles per square meter for ELIO and 4007, respectively. N uptake by these two cuhivars was generally increased with increasing of N application rates, but N utilization efficiency for grain yield （NUE） decreased with increasing N application rates. NUE of 4007 was significantly higher than that of ELIO at all N application rates, mainly resulting from its higher NHI potential. NUE was negatively correlated with stem and leaf N concentration at maturity, suggesting that the effective nitrogen translocation from the vegetative tissues to the grains during the post-anthesis period was one of main causes resulting in a higher NUE. In addition, 4007 generally had higher partitioning parameters, such as agronomic N use efficiency, apparent recovery of applied N and partial factor productivity for applied N, than ELIO at all N application rates. Therefore, it was suggested that 4007 had advantages over ELIO under both N limited and sufficient conditions. It is feasible to optimize productivity and reduce the pollution risk for the environment in rice production sy