局部根系水分胁迫下不同形态氮素营养对水稻幼苗生长的影响

为区分水稻根系与地上部对水分胁迫的生理响应，采用分根营养液培养及聚乙二醇（PEG6000）模拟水分胁迫的方法，研究了局部根系在水分胁迫下不同形态氮素营养(NH4+、NO3- 、NH4+与NO3-等体积混合) 对水稻幼苗水分与氮素吸收利用的影响。结果表明： 1）全根水分胁迫显著抑制了单供NO3- N营养条件下水稻的生长，而对单供NH4+ N营养条件下水稻生长的影响较小。局部根系水分胁迫对3种供氮形态营养下水稻总生物量没有明显影响，但对单供NO3- N营养水稻根系的生物量、根系总长、根体积、平均直径以及根表面积的影响最大，均以未受水分胁迫的一侧根系生物量明显高于另一侧（受水分胁迫）。2）水分胁迫促进根系对NO3- N的消耗。3）全根水分胁迫严重抑制了单供NO3- N营养水稻的光合速率，但对单供NH4+ N营养水稻的影响较小。不论局部根系水分胁迫还是全根水分胁迫对3种供氮形态的生理水分利用率均无显著影响。4）全根水分胁迫显著降低了单供NO3- N营养水稻的光合氮素利用率。

Effects of Different Nitrogen Forms on Rice Seedlings Growth with Partial Roots Exposed to Water Stress

In order to distinguish the different physiological response of the roots and shoots of rice to water stress,the effects of different nitrogen forms on the growth of rice seedlings were studied by using a split-root system and simulated water stress(by adding 100 g/L PEG6000) with three nitrogen forms(NH_4~+,NO_3~-and mixture of NH_4~+ and NO_3~-) supply.The results showed that: 1) The growth of NO_3~--N supplied rice plants were significantly inhibited by water stress,however,no pronounced differences were found under NH_4~+-N supply.The biomass of rice was not affected by partial-root water stress in the three nitrogen forms,but rice root parameters with sole nitrate supply decreased significantly under water stress compared to those without water stress.2) Water stress stimulated the absorption of NO_3~--N.3)The photosynthesis was inhibited by water stress under NO_3~--N supply,but no effects were noted under NH_4~+-N supply;the physiological water use efficiency was not affected by either total or partial-root water stress under three nitrogen forms.4)Under the total water stress,photosynthetic nitrogen use efficiency was decreased under NO_3~--N supply.