中文摘要：

采用控制条件下的水培试验方法，研究了不同铵硝配比（SH^＋4／N03^-3分别为100／0、75／25、50／50和25／75）营养条件对8种不同氮素利用效率水稻苗期生长的影响。结果表明：在增硝营养条件下，不同水稻品种对硝态氮（N03^-3）的反应不同。与纯铵营养条件相比，铵硝混合的营养条件对大多数氮高效水稻品种的生长都有显著促进作用，而对氮低效品种的生长没有显著影响。试验重点研究了增硝营养对氮高效水稻品种南光、云粳38和氮低效水稻品种ELIO生长能影响。结果发现，对于南光和云粳38，增硝营养可以使水稻的分蘖数和光合速率分别增加35％和24％，从而促进水稚生长和氮吸收，提高氮素利用率；而增硝营养对ELIO的生长并无显著影响。不同基因型水稻在增硝营养下氮积累量增幅不同主要是由于其生物量增幅不同造成的，而整株氮素含量增幅差异不大；N03^-3的存在可增加干物质在水稻根系能积累，增加根系体积，促进水稻根系的生长。

英文摘要：

As the rice plant is increasingly cultivated in the soil intermittently irrigated or even in aerobic soil in which nitrate nutrition of rice is more important than ever before, there are many evidences of enhanced effect by nitrate （ N03^-3 ） on rice crop although it prefers the ammonium （ SH^＋4 ） nutrition to nitrate. Solution culture experiment were carried out to study the effects of different ratios of SH^＋4/N03^-3 （ SH^＋4/N03^-3 as 100/0, 75/25, 50/50 and 25/75 ） on the biological characteristics of eight genotypes of rice with different nitrogen （N） efficiency at the seedling stage. The results obtained were as follows. Different rice genotypes had different responses to N03^-3 Among the eight rice genotypes, the improvement of growth by N03^-3 to the rice genotypes with higher N use efficiency was greater than that with lower N use efficiency. Furthermore, we compared the growth of Nanguang （higher N efficiency）, Yunjing 38 （higher N efficiency） and ELIO （lower N efficiency） at the ratio of SH^＋4/N03^-3 as 75/25 and 100/0. The tillers and photosynthetic rate in the leaves of Nanguang and Yunjing 38 were averagely increased by 35% and 24%, respectively, while those of ELIO had no significant difference, between the treatments of 75/25 and 100/0. It was not the N content but the increased dry matter that partial replacement of SH^＋4 by N03^-3 contributed to N accumulation in rice plants. N03^-3 could improve the accumulation of dry matter in the roots of Nanguang and Yunjing 38 and increase the volume of roots of Nanguang, Yunjing 38 and ELIO.