以氮素利用效率差异大的两个水稻品种（氮高效品种南光和氮低效品种Elio）作为试验材料，设计高低两个供氮水平，在温室砂培条件下研究了不同氮效率水稻高效吸收利用氮素的根系生物学特性及生理机制。结果表明，在两个供氮水平下，氮高效水稻南光的产量均显著大于氮低效水稻，增幅在50%以上。随着供氮水平的提高，两个水稻品种植株的总吸氮量和干物质量随之增加，氮高效水稻南光的生育后期吸氮量和地上部及根系的生物量显著高于氮低效水稻Elio；氮高效水稻品种南光根系形态参数对氮素营养的响应度高于氮低效品种Elio，高氮处理下，南光较低氮处理分别增加127%（总根长）和114%（根系表面积），而Elio仅增加92%（总根长）和82%（根系表面积），而且Elio在齐穗期后根系形态参数水平下降显著；南光的根系伤流强度在拔节期较氮低效水稻Elio高出11%（1mmol L-1）和32%（5mmol L-1），灌浆期南光较Elio高出12%（1mmol L-1）和12%（5mmol L-1），差异均显著。由本试验结果可推断根系形态及根系活力的差异是造成水稻氮效率差异的重要原因之一。
Sand culture was conducted to study the root morphologic characteristics and physiological indices in two rice cultivars with different N use efficiency (NUE), Nanguang with high NUE and Elio with low NUE, under two N rates (1 and 5mmol L-1). The results obtained were listed as follows. Compared to Elio, grain yields of Nanguang were more than 50% under two N rates. Nitrogen and biomass accumulation in rice cultivars increased with increasing N application rates But nitrogen and biomass accumulation of Nanguang were much greater than these of Elio at the latter growth stages.The root morphologic characteristics in high NUE rice cultivar (Nanguang) had more sensitive responses to high N application rates than the low NUE rice cultivar (Elio). Compared to N application rate of 1mmol L-1, root lengths were 127% greater in Nanguang and 92% greater in Elio under N rate of 5mmol L-1; and root surface areas were 114% greater in Nanguang and 82% greater in Elio. Root morphological characteristics of Elio with low NUE rice cultivar, decreased more rapidly than Nanguang after the heading stage. Root bleeding rates of Elio were lower than that of Nanguang at different growth stages. Compared to Elio, root bleeding rate of Nanguang were 11%（1mmol L-1）and 32%（5mmol L-1）greater at jointing stage and 17%（1mmol L-1）and 18%（5mmol L-1）greater at heading stage. It was concluded that efficient N use of rice cultivar depended to a great extent on greater root morphological characteristics and stronger root physiological activity.