GROWTH AND CHEMICAL COMPOSITION OF ANANAS COMOSUS (L.) MERR., IN SOLUTION CULTURES WITH DIFFERENT IRON-MANGANESE RATIOS

Abstract

Most satisfactory growth was obtained with culture solutions containing 0.5 Fe and 5.0 Mn. Where ammonium nitrogen was supplied, concentrations of Mn in the tissues were only half as great as where nitrate nitrogen was given, due presumably to antagonism between Mn++ and NH4+. Iron concentrations, however, were greater in the tissues of the ammonium cultures. Certain amounts of iron and manganese in the leaf tissues were in combination with definite protein fractions, the amounts of protein increasing with iron but decreasing with manganese. The tissues of high-Mn cultures contained more Mg than those of low Mn cultures, but absorption of other nutrients was unaffected. The effect of the Fe/Mn ratio of the solution on the sugar, starch, and ascorbic acid content of the tissues was also investigated. It is suggested that Mn chlorosis may result from a replacement of Fe by Mn in the pyrrole ring of protoporphyrin 9, a precursor of chlorophyll.