中文摘要：

采用大田试验，以长江中下游地区有代表性的50个早熟晚粳品种为供试材料，设置7个氮肥水平（0、 150.0、 187.5、 225.0、 262.5、 300.0、 337.5 kg/hm2），得出各品种在这7个氮肥水平下出现的群体最高生产力，将该最高生产力定义为氮肥群体最高生产力。根据各品种的氮肥群体最高生产力从高到低将50个品种分为4个产量水平，对不同产量水平品种间各器官的干物质和氮素积累转运、 分配等特性进行系统地比较研究。结果表明，抽穗期叶片的氮素含量和氮素积累量以及成熟期叶片和穗的干物质与氮素积累量随产量水平递减逐渐降低; 拔节至抽穗阶段茎鞘的干物质积累率以及叶片的干物质和氮素积累速率也随产量水平递减逐渐降低; 抽穗至成熟阶段产量大于10.50 t/hm2的水稻品种，茎鞘和叶片的干物质和氮素转运贡献率比其他产量水平低，但穗部干物质和氮素增加量却比其他产量水平高。在满足氮肥群体最高生产力的施肥条件下，拔节至抽穗阶段叶片的干物质、 氮素积累速率和产量呈极显著正相关（r=0.635, r=0.539），抽穗至成熟阶段叶片的干物质转运量与产量呈显著负相关（r=-0.360），而叶片的氮素转运量与产量呈显著正相关（r=0.333）。产量大于10.50 t/hm2的水稻品种叶片的干物质和氮素积累与转运比其他产量水平品种在抽穗后表现出明显的优势，穗部物质积累与氮素积累量较高。抽穗后在保持茎鞘适宜的物质和氮素积累量的基础上，提高叶片的物质和氮素积累，进一步加大穗部的物质和氮素积累，是获得高产的保障。

英文摘要：

A field experiment was carried out to investigate the productivity of rice under the nitrogen fertilization. There were 50 early-maturing late Japonica rice cultivars which are adopted in the region of Yangtze River, and seven nitrogen levels, 0, 150.0, 187.5, 225.0, 262.5, 300.0, and 337.5 kg/ha. The highest productivity of rice cultivar under the seven nitrogen levels was defined as the highest population productivity of N fertilization （HPPN）. Then according to HPPN, rice cultivars are classified into four types, top type, high type, middle type and low type. On this basis, the accumulation and translocation of dry matter and N of the four types of rice cultivars were studied. The main results show that the N concentrations and accumulation of leaves are decreased as the decrease of the productivity level at the heading. Also the dry matter and N accumulations of leaves and panicles at the maturity are decreased as the decrease of the productivity level at the maturity. From elongation to heading, the rate of dry matter and N accumulation of stems-sheaths/leaves are decreased as the decrease of the productivity level at the maturity. From the heading to maturity, the dry matter/N TCRV （translocation conversation rate of vegetative organ） of stems-sheaths/leaves of the top level are smaller than those of the other three levels, while the increase of dry matter/N accumulation in panicle are bigger. There are significant positive correlations between dry matter/N accumulation rate and HPPN from the elongation to heading（r=0.635, r=0.539）. From the heading to maturity, there is a significant negative correlation between dry matter translocation of leaves and HPPN （r=-0.360）, while there is a significant positive correlation between N accumulation of leaf and HPPN （r=0.333）. The rice cultivars which yield are more than 10.50 t/hm2 have obvious advantages than other cultivars in nutrition of dry matter and N of leaves after the heading of rice. Therefore, appropriate dry matter and N accumulation