EFFECTS OF IRON ON CERTAIN NITROGENOUS FRACTIONS OF ANANAS COMOSUS (L.) MERR

Abstract

The plants grown in the ammonium series contained greater amts. of total N than those in the nitrate N series. The leaves and stem but not the roots of the plants of the plus-iron cultures in the ammonium-N series contained slightly greater amts. of total N than of the minus-iron cultures. The differences in total N between the plus- and minus-iron cultures were greater in the nitrate-than ammonium-N series and they were in favor of the former cultures. The amide- and amino-N content of the tissues was greater in the ammonium- than in the nitrate-N series. In the former series the plus-iron cultures contained more amide- and amino-N than the minus-iron cultures. In the nitrate-N series, the plus-iron cultures contained more peptide- and proteose-peptone-N than the minus-iron cultures. These results indicate that the primary products of ammonium assimilation were amide- and amino-N compounds and suggest that protein synthesis in plants supplied with ammonium-N was via these compounds. In the plants supplied with nitrate, protein synthesis from inorganic N compounds was apparently different than with ammonium. Statistically significant differences were obtained in the amts. of organic-N, peptide-N, basic-N and proteose-peptone-N between the plus- and minus-iron cultures of the nitrate-N series which were in favor of the plus-iron cultures, whereas in the ammonium-N series such differences were obtained in the organic-N and protein-N fractions. In the ammonium-N series, basic N was the only fraction highly significant in favor of the minus-iron cultures.