ASSIMILATION AND TRANSPORT OF NITROGENOUS COMPOUNDS ORIGINATED FROM ^<15>N_2 FIXATION AND ^<15>NO_3 ABSORPTION

概要

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Nodulated leguminous plants utilize both combined nitrogen absorbed by roots and gaseous nitrogen fixed by root nodules. In order to elucidate the physiological role of N_2 fixation compared with NO_3 absorption, the assimilation and transport of nitrogenous compounds from these nitrogen sources were studied. One part of soybean plants was administered with labeled nitrogen gas and unlabeled nitrate, and another part with unlabeled nitrogen gas and labeled nitrate. After feeding of labeled compounds to roots, ammonia, nitrate, amino acids, amides and allantoin in nodules, roots and stems were separated, and ^<15>N content of them were determined optically using JASCO NIA-1 ^<15>N-analyzer. In nodules supplied with ^<15>N_2,high ^<15>N contents were found in glutamate, alanine, serine, γ-amino-butyrate, but in roots supplied with ^<15>NO_3,asparagine showed the highest ^<15>N content after 8 hr ^<15>N feeding. In stems, allantoin showed the highest ^<15>N content in the case of ^<15>N_2 treatment, and the ratio (^<15>N from ^<15>N_2/^<15>N from ^<15>NO_3) of allantoin showed 10-50 fold higher than the ratios of other compounds, suggesting that allantoin was actively synthesized in nodules.
一般社団法人日本土壌肥料学会の論文