局部根系水分胁迫下氮素形态对水稻幼苗生理特性和根系生长的影响

Effects of N Forms on Physiological Characteristics and Root Growth of Rice Seedling in Condition of Partial Root Water Stress

为了探讨局部根系水分胁迫下不同形态氮素对水稻幼苗氮素吸收、生理特性和根系生长的影响,以水稻品种金优402为材料,设置非胁迫、局部根系胁迫、全根胁迫3种水分条件和全硝、铵硝比为50/50、全铵3个氮素形态,采用PEG模拟水分胁迫的室内分根营养液培养方法,研究其氮素吸收和累积、光合速率、蒸腾速率、气孔导度及根长、根表面积、根体积的变化规律。结果表明,在局部根系水分胁迫下,两侧根系同时供应NH_4^+-N和NO_3^--N最有利于水稻氮素的吸收和累积,两侧根系均单一供应NO_3^--N的水稻氮素吸收和累积量最少;与未受胁迫处理的水稻相比,局部根系胁迫下两侧根系同时供应NH_4^+-N和NO_3^--N的水稻光合速率受影响较小,而气孔导度和蒸腾速率则明显下降。不同氮形态处理间,两侧根系同时供应NH_4^+-N和NO_3^--N的水稻光合速率和气孔导度均为最大,单一供应NO_3^--N的最小。在所有处理中,局部根系水分胁迫下两侧根系同时供应NH_4^+-N和NO_3^--N的水稻WUE最高。在局部根系水分胁迫下,两侧同时供应NH_4^+-N和NO_3^--N的水稻根长、根表面积、根体积绝大多数大于其他2种氮素形态,且受胁迫一侧和不受胁迫一侧根系相差较小。除左右根室均单一供应NO_3^--N的水稻外,局部根系胁迫处理的根长、根表面积、根体积均大于非胁迫处理。研究结果表明,局部根系水分胁迫和氮素形态耦合可以提高水稻幼苗的水、氮素吸收。

To study the response of rice Jinyou 402 seedling to nitrogen forms under partial root drying condition,a hydroponic experiment simulated by PEG was conducted using the method of nutrient solution culture.The trials had three water conditions: non-water stress,partial root drying,and all root water stress,and three nitrogen forms: NH4^+-N/NO3^--N of 0/100,50/50,100/0).Nitrogen absorption and accumulation,photosynthetic rate,transpiration rate,stomatal conductance,root length,root surface area and root volume of rice were determined.The results showed that under partial root drying condition,supplying both NH4^+-N and NO3^--N were most beneficial to nitrogen absorption and accumulation of rice seedling;The nitrogen absorption and accumulation were the minimum when NO3^--N was supplied in two sides of root;The photosynthetic rate of rice,supplied with NH4^+-N and NO3^--N,were not affected obviously,but the transpiration rate and stomatal conductance declined significantly under partial root drying condition,compared to the rice with no water stress.The photosynthetic rate and stomatal conductance of rice supplied with NH4^+-N and NO3^--N in two sides of root were the highest among different nitrogen forms,and the lowest supplied with single NO3^--N.WUE of rice supplied with NH4^+-N and NO3^--N was the biggest under the condition of partial root water stress.In condition of partial root drying,root length,root surface area,and root volume of most rices supplied with NH4^+-N and NO3^--N were all greater than those of rice supplied with single NH4^+-N or NO3^--N,and there were no significant difference between two sides of root.Furthermore,root length,root surface area,and root volume of rice subjected to partial root water stress environment were all greater than those with no water stress treatments,except for rice supplied with only NO3^--N in two sides of root.This research proved that the interaction of partial root drying with nitrogen forms could promoted the water and nitrogen absorption of rice seedlings.