Abstract: A population of chromosome segment substitution lines (CSSLs), derived from the cross between an indica variety IR24 and a japonica variety Asominori was used to mearure the total content of nitrogen in flag leaf at different stages with seven-day intervals. Based on the rice genetic linkage map of 118 molecular RFLP markers, QTLs for the developmental behavior of total nitrogen content in flag leaf were determined dynamically using composite interval mapping method at five different stages. Seven QTLs in total, underlying nitrogen content in flag leaf were detected at the whole stages. However, only two QTLs were detected at the final stage. By comparing the sum of QTL additive effects for parents with that for extreme ideal individuals, it was found that the alleles of positive or negative gene effects were dispersed in various individuals. The result also indicates that two sets of genes might be involved in the changing process of total nitrogen content in flag leaf. The total nitrogen content in flag leaf at earlier stage is determined by one set of genes which could be used for photosynthesis improvement, while at later stage it is controlled by the other set of genes which could be applied for delaying the senescence of flag leaf.

Key words: rice, flag leaf, nitrogen content, photosynthesis, quantitative trait locus

摘要： 以籼稻品种IR24 和粳稻品种Asominori 及其染色体片段置换系（CSSLs）群体为遗传研究材料, 在抽穗后5个不同时期分别测定剑叶全氮含量，并结合水稻RFLP分子标记连锁图谱,对水稻剑叶全氮含量性状进行QTL的动态定位，探讨了控制剑叶全氮含量基因在水稻发育过程中的时序表达方式。在抽穗后各时期共检测到7个QTL, 位于第2和第11染色体上的2个QTL（QN2、QN11）增效基因来自粳稻品种Asominori，其他QTL的增效基因来自籼稻IR24；抽穗后2周内检测到2个QTL，即QN3和QN8b, 其加性效应值较大, 解释表型变异的贡献率较高；后期检测到的QTL加性效应和贡献率较低，位于第2染色体上R3393的QN2位点的基因在抽穗后第3周内表达, 位于第8染色体上G1149的QN8位点的基因在抽穗后第4周内表达，位于第11染色体上G1465的QN11位点的基因在抽穗后４周和５周持续表达。控制剑叶全氮含量的基因在抽穗后早期表达较为活跃，可以应用于改良水稻品种的剑叶光合功能；在测定末期检测到的控制剑叶全氮含量的QTL，则可以用于延缓叶片早衰的育种改良。

关键词: 水稻, 剑叶, 全氮含量, 光合作用, 数量性状基因座位