不同水稻基因型苗期NO_3^-吸收动力学特征及其受吸收液中NH_4^+的影响

Kinetics of Nitrate Uptake by Different Rice Genotypes and the Effects of Ammonium on Nitrate Uptake at the Seedling Stage

采用水培方法研究了 12个水稻品种和 2个旱稻品种在苗期 (2 0d)的NO3 -吸收动力学特性及添加吸收液中NH4+ 对NO3 -吸收的影响。结果表明 ,NO3 -吸收的最大速率 (Vmax)为 :旱稻 >水稻 ,籼稻 >粳稻 ,杂交稻 >常规稻。NH4+ 对NO3 -吸收Vmax的影响在基因型间有较大差异 :籼稻受影响小于粳稻 ,杂交稻小于常规稻 ,旱稻基本不受影响。NH4+ 对个别籼稻和旱稻品种的NO3 -吸收甚至有促进作用。NH4+ 对所有供试水稻基因型NO3 -吸收的Km 值影响均很小 ,说明NH4+ 对NO3 -吸收的影响可能主要在于影响细胞膜上NO3 -载体的运转速率而非吸收位点与NO3

Solution culture experiments were carried out to study the kinetics of NO 3 - uptake by different rice genotypes, including 12 varieties of wetland rice and 2 varieties of upland rice, and the effects of NH 4 + on NO 3 - uptake were assessed. The results indicated that at the seedling stage (20 days) upland rice had higher maximum rate (V max) of NO 3 - uptake than wetland rice, Indica showed higher V max than Japonica, and Hybrid rice presented higher V max than common rice. The effects of NH 4 + on V max of NO 3 - uptake differed greatly among the rice genotypes: Indica rice was less influenced than Japonica rice; Hybrid rice was less restrained than common rice; upland rice was hardly inhibited; certain varieties of Indica rice and upland rice even were stimulated with the existence of NH 4 +. On account of the slight influence of NH 4 + on the values of K m of all tested genotypes, it seems that the effects of NH 4 + on NO 3 - uptake are mainly due to the influence on the transporting rate of nitrate carriers located at the cell membrane, but not due to the influence on the affinity of the uptake sites for NO 3 -.