不同氮效率小麦品种苗期根系的NO_3^-、NH_4^+吸收动力学特征

Kinetics of Nitrate and Ammonium Uptake by Different Wheat Genotypes at Seedling Stage

为了给氮素高效利用品种的选育提供依据,采用水培方法研究了3个不同氮效率小麦品种(秦麦11、扬麦9号、扬9817)苗期根系NO3-、NH4+吸收动力学特性的差异及培养液中添加NH4+对根系NO3-吸收的影响。结果表明,3个不同氮效率小麦品种苗期根系对NO3-和NH4+吸收的最大速率(Vmax)和亲和力(1/Km)有显著差异,表现趋势均为:秦麦11>扬麦9号>扬9817。氮高效品种苗期根系对NO3-、NH4+的吸收显示出了较为明显的优势,而且对NH4+的吸收动力学参数均大于对NO3-吸收的参数。NH4+的存在明显抑制了根系对NO3-的吸收,主要表现为对NO3-吸收速率(Vmax)的影响,而不是对亲和力值(1/Km)的影响。表明根系氮素吸收动力学特征的测定可以作为确定高产优质小麦最适施氮量的参考依据,同时亦可作为小麦育种高世代材料选育氮高效吸收小麦品种的方法之一。

Solution culture experiments were carried out to study the kinetics parameters of NO3^- and NH4^＋ uptake by three different wheat genotypes with different N efficiency, and the effects of NH4^＋ on NO3^- uptake were assessed. The results indicated that the kinetics parameters of NO3^- and NH4^＋ uptake by three different wheat genotypes were significantly different at 0.05 level . The order of maximum absorption rate （Vmax） and affinity （1/Km） among different varieties was Qinmai 11〉Yangmai 9〉Yang 9817. The varieties with higher N efficiency were superior to those with lower N at seedling stage, and the kinetics parameters of NH4^＋ uptake were greater than those of NO3^- uptake. The kinetics parameters of NO3^- uptake were inhibited by the existence of NH4^＋ , it might mainly reduced the Vmax of NO3^-. So, kinetics parameters of N uptake of different wheat genotypes could be used not only as a reference for confirming appropriate N quantity which could get high yield and good quality, but also as a method of selecting wheat variety with high N efficiency.