中文摘要：

选用低产氮低效型、高产氮中效型和高产氮高效型具有代表性的6个粳稻品种，在各基因型各自最适氮素水平下，研究了茎秆力学特性、物理特性和化学成分含量的差异及其与氮效率的关系。结果表明：（1）较之低产类型品种，高产类型品种茎秆基部N1节间变短、N6节间变长，株高有所增加；茎粗、茎壁厚、茎鞘干重均极显著增加；茎鞘的K、Si含量极显著增加，N含量显著降低。由于茎秆物理性状的改善及化学成分的差异导致茎秆综合抗折力明显提高，倒伏指数降低。（2）同为高生产力类型品种，因氮效率的差异茎秆形态生理特征表现不同。较之高产氮中效类型，高产氮高效类型水稻品种茎秆N4、N5节间变长；茎秆粗度略有降低，但茎壁厚增加，表现茎秆干重增加，充实度加强；茎鞘的K含量无明显变化，但Si含量显著降低，N含量也呈降低趋势。对于高产品种，适当增加N4、N5节间长度以改善叶片配置，适当降低茎粗而提高壁厚和充实度以保证茎秆抗折力和输导能力，适当降低茎鞘Si含量以促进氮素的转移，有利于进一步提高氮肥利用率。

英文摘要：

The morphological and physiological characteristics of low-yielding and low N-efficiency, high-yielding and medium N-efficiency, high-yielding and high N-efficiency of rice cultivars were investigated using six representative japonica varieties under their respective optimal N application levels. The results showed that compared with low-yielding varieties, high-yielding varieties showed shorter basal 1st internodes, longer basal 6th internodes, increased plant height, larger culm diameter and wall thickness, significantly higher dry weight of stem and sheath, obviously increased K and Si content in culm and sheath, and a higher ratio of Si to N. As a result of their improved stalk physical characteristics and the different chemical compositions, the comprehensive breaking resistance of the culm of high-yielding culfivars was improved evidently, and the lodging index reduced as well. The cultivars with different N-efficiencies displayed diverse culm morphological and physiological characteristics even though they were all in one high-yielding level. Comparing with medium N-efficiency genotypes, the high N-efficiency ones had longer 4th and 5th internode lengths, increased culm wall thickness, in spite of slightly decreased culm diameter, resulted in higher dry weight and strengthened plumpness status of culm, significantly decreased content of Si in stem and sheath, decreased N content, and remarkably unchanged K content. Given these results, for the purpose of further increasing the nitrogen fertilizer use efficiency of the high-yielding varieties, it would be favorable to properly increase 4th and 5th internode length, thus improv- ing top three leaves configuration, to appropriately reduce the culm diameter while increasing wall thickness and filling degree for the sake of stalk breaking resistance and transporting capability, and to properly reduce the content of Si in culm and sheath to facilitate the translocation of nitrogen.