ASCORBIC ACID AND DRY MATTER ACCUMULATION IN TURNIP AND BROCCOLI LEAF DISCS AFTER INFILTRATION WITH INORGANIC SALTS, ORGANIC ACIDS, AND SOME ENZYME INHIBITORS

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Abstract
Infiltration with solns. of inorganic salts influences ascorbic acid accumulation in illuminated leaf discs of turnips and broccoli. This accumulation is depressed by ammonium salts in general. Chlorides and sulfates of NH4, K, and Ca depress ascorbic acid accumulation more than do nitrates. K+, Ca++, and NH4+ represent a series in which K+ influences the process little, NH4+ reduces the rate of accumulation rather greatly, and Ca++ effects an intermediate response. If inorganic salts are supplied in solns. which are more or less physiologically balanced, similar relationships between ions are observed. H2PO4" supplied as the single anion source in the presence of a balance of Ca++, Mg++, K+, and NH4+ caused a marked decrease in the rate of ascorbic acid accumulation. Citrate and acetate (pH 5) depressed this process markedly at low concns. (0.005-0.01 [image]). Malonate and tartrate also depressed ascorbic acid accumulation, whereas succinate and L-malate had little or no effect at similar concns. 8-Hydroxyquinoline reduced both ascorbic acid accumulation and net photosynthesis, each to about the same extent. Most of these salts, both inorganic and organic, influence ascorbic acid accumulation somewhat more than the accumulation of dry matter, if they have any effect at all. Nevertheless, a close correlation was observed between the changes in ascorbic acid and dry matter (r = +0.83, n = 156). It is suggested that ascorbic acid contributes to the cation-anion balance in leaf tissue.