| Abstrakt: |
A balance sheet showing changes in amounts of nitrogenous substances in oat leaves during starvation is presented for two different experiments. Determinations of protein, peptides, residual amino acids, glutamine, asparagine, arginine, ammonia, nitrate, purines, betaine and choline, and basic-nitrogen have been made, all expressed in terms of their nitrogen contents. Up to onset of browning of the leaves, amounts of these substances account for 95-100 p.c. of the total-N. No change in amounts of nitrate-N, betaine and choline-N and purine-N could be detected during the starvation period; the major changes involving redistribution of nitrogen of protein, peptides, amino acids, amides and ammonia. With onset of browning loss of total-N occurred from the leaves and the substances estimated accounted for only 75-80 p.c. of the total-N present in the leaves. Malic and citric acids increased in amount during starvation and the evidence suggests that part of these acids was derived from nitrogenous sources (probably amides) but that no simple relationship exists between amides and acids. [ABSTRACT FROM AUTHOR] |
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