菠菜不同生长阶段吸收硝态氮的动力学研究

通过对两种菠菜不同生长阶段的氮素吸收情况和硝态氮吸收的动力学分析 ,结果表明 ,两种菠菜吸收氮素的差异随生长时期而不同 ,宁夏圆叶菠菜比日本超能菠菜更具喜硝性 ,且越在生长的后期 ,该特性越显著。植株苗期对硝态氮的亲和力大小不能准确反应菠菜不同生长阶段的实际吸收情况 ,而应根据生长的不同时期求得相应的亲和力。吸收速率单位在生长前期采用单位时间单位根重的吸收量来表示 ,生长后期采用单位时间单位株重的吸收量来表示 ,求得的亲和力才能反映两种菠菜吸收硝态氮的实际差异。

Study on the kinetics of NO3-N absorption by two spinach varieties

Solution culture experiments indicated that the differences of nitrogen absorption between two spinach varieties were various at different growth stages.Ningxia spinach is more favorable to NO 3-N than Japanese spinach,especially in the late growth stage.A series of Km values were obtained graphically by Lineweaver-Burk methods based on the enzyme kinetic equation and by using different absorption velocity units.The results indicated that the differences of Km values calculated during the seedling growth stage of two spinach varieties were not be used to show the differences on NO 3-N absorption in the total growth stage.The difference of NO 3-N absorption abilities at one growth stage could be showed by Km values at the same period,but the Km value must be obtained according to selecting suitable absorption velocity unit.It was suggested that the absorption velocity unit should select the amounts of NO 3-N absorption per root weight per hour at the early growth stage,and that it should be the amounts of NO 3-N absorption per plant weight per hour at the late growth stage.