EFFECTS OF POTASSIUM ON THE NITROGENOUS CONSTITUENTS OF ANANAS COMOSUS (L.) MERR

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Abstract
High-potassium cultures (205 mg. per 1.) compared with low-K cultures (4 mg. per 1.), supplied with equal amts. of N either as nitrate or ammonium, modified the relative amounts of different nitrogenous fractions in the tissues of A. comosus. Nitrate N, as indicated by the nitrate content of the basal leaf and stem sections, was greater in the high-K cultures in the nitrate series. Ammonium N, generated possibly by deaminizing processes, occurred in traces in the plants of both series. Ammonium absorbed from nutrient solns. was readily converted to compounds of greater complexity in the roots, and it is doubtful that any passed from roots to stem unchanged. Soluble organic N, calculated as mg. per gram of fresh wt., was higher in the low-K cultures of both series. Protein N in the leaves, calculated as mg. per gram of tissue, was greater in the low-K cultures, but in the stem these values were reversed. Calculated as total protein N per organ or plant, the values were greater for the high-K cultures in both leaves and stem. The data indicate that the physiol. function of K in the conversion of soluble organic N fractions to protein N is more noticeable in the stem than in the highly differentiated tissues of fully expanded leaves. In the. leaves, protein N was higher in the low-K cultures. The higher content of protein N in the stems of the high-K cultures is attributed to the conditions in the peripheral and apical regions of the stem, which, composed mostly of meristematic tissues and possessing potential growth activity, require greater quantities of proteins for the regeneration of protoplasm than similar tissues of the low-K cultures which lack equally great growth potentialities.