ASSIMILATION AND TRANSPORT OF NITRATE, NITRITE, AND AMMONIA ABSORBED BY NODULATED SOYBEAN PLANTS

概要

論文の詳細を見る
Nodulated soybean plants were treated with a culture solution containing ^<15>NO_3^-, ^<15>NO_2^-, or ^<15>NH_4^+, and the fates of these N sources were compared in the roots, nodules, stems, and leaves. The absorption rates of N and their partitioning patterns in the shoots were very similar for ^<15>NO_3^- and ^<15>NH_4^+. Either N source was rapidly transported to the stems and leaves, and readily incorporated into proteins. However, ^<15>NO_2^- absorption was only half as high as that of ^<15>NO_3^- or ^<15>NH_4^+. In addition, the N originating from ^<15>NO_2^- was transported very slowly to the shoot organs, and accumulated in the roots especially in the form of glutamine and proteins. It was observed that the ^<15>NH_4^+ or ^<15>NO_2^- applied was rapidly translocated into the nodules without a lag-phase. However when ^<15>NO_3^- was added, a time-lag was observed in the incorporation of ^<15>N into the nodules. The oxidation of nitrite to nitrate was assumed to have taken place in the nodules, and the activity was also detected in the isolated bacteroid suspension. ^<15>NO_3^- administration resulted in the accumulation of ureides and asparagine in the nodules. On the other hand in the ^<15>NH_4^+ or ^<15>NO_2^- treatment, the accumulation of ureides and asparagine was observed in the stems. The ureide content in the leaves was markedly increased by the ammonium treatment.
社団法人日本土壌肥料学会の論文