EFFECTS OF EXOGENOUS AMINO ACIDS ON THE FLOWER AND FROND PRODUCTION IN DUCKWEED, LEMNA GIBBA G3

1. Twenty usual amino acids examined were shown to be dividedinto two groups with respect to their actions on the flowerformation (A) and frond multiplication (B) in a long-day duckweed,L. gibba G3. Amino acids of the first group (e.g., arginine)inhibited A without preventing B, and those of the second group(e.g., lysine) inhibited both A and B. The inhibition of flowerformation was always the greatest when amino acid was appliedat the induction period. 2. The floral inhibition by arginine applied at the inductionperiod was partially or wholly reversed by the simultaneousaddition of other amino acid (especially lysine) or by one additionallong day. The inhibitions by lysine, however, were not reversedby arginine. 3. It was discussed that the terminal step(s) of photoperiodicinduction process might depend largely on the relative in vivoconcentrations of amino acids. (Received January 28, 1964; )