Studies in the Metabolism of Crassulacean Plants; The Effect upon the Composition of Bryophyllum calycinum of the Form in which Nitrogen is Supplied

Abstract

In general, the experimental procedure used to determiine the availability of nitrate or ammonium ions to plants has involved culture solutions that provide but one of the two ions. In experiments of this sort in recent years, care has been taken to maintain the pH of the solution within a range found appropriate for absorption by plants. The work in this field by Dr. J. W. SHIVE and his associates at the New Jersey Agricultural Experiment Station has been outstanding; TIEDJENS and ROBBINS (11), for example, have shown that tomato and soybean plants grown at pH 7.9 in ammonium salt culture solution, or at pH 4.0 in nitrate solution, were almost equally well developed.The effect upon the detailed chemical composition of tomato plants grown under the two conditions has been studied in this laboratory by CLARK (2), who observed that the organic acid content of leaves and stalks was greatly depressed in plants grown in ammonium salt solution as compared with those grown in nitrate solution. Protein and several soluble nitrogenlous components were, on the other hand, increased in the plants grown on amiimonium salts, the production of glutamine in particular being enormously stimulated. Detailed comparison of the effects of the two different nutrient conditions was made difficult, however, by the fact that the plants grown with ammonium salts were much smaller than those grown with nitrate, although both were setting fruit at the time of harvest.In order to follow more closely the effect upon tissue composition of nitrate versus ammonium salt nutrition, it is desirable to grow the plants in a series of culture solutions of similar over-all composition, but with the relative proportion of nitrate to ammonium ions varied in regular steps from all-nitrate nitrogen to all-ammonium nitrogen. Such an experiment 205www.plantphysiol.org on May 7, 2018 -Published by Downloaded from

Ascorbic Acid and Dry Matter Accumulation in Turnip and Broccoli Leaf Discs After Infiltration With Inorganic Salts, Organic Acids, and Some Enzyme Inhibitors

“…In a comparison between K+ and NH4+ a similar situation occurs, except that in this case organic anions must be reduced in amount to balance the NH4+ metabolized by the cells. The relative effects of ammonium and nitrate ions upon ascorbic acid accumulation are likewise similar to those observed with other organic acids in higher plant tissues (5,17,27). Ammonium ions result in smaller amounts of the various organic acids in the tissues than do nitrates.…”

Studies in the Metabolism of Crassulacean Plants: The Diurnal Variation in Organic Acid and Starch Content of Bryophyllum calycinum

“…The identification in this laboratory of isocitric acid as one of the major organic acid components of Bryophyllum calycinum leaves (9,12), and also independently at the same time by Nordall (8) in two other species of Crassulaceae, has solved the problem of the nature of the so-called crassulacean malic acid and throws light upon WOLF'S statements regarding the unknown optically active organic acid of Bryophyllum leaves. Moreover, the development in recent years of analytical techniques for the common plant organic acids as well as the advances that have been made in the theoretical approach to the understanding of carbohydrate metabolism in living tissues suggested that a reinvestigation of one of the oldest problems in plant biochemistry might be rewarding.…”

Physiological Studies on Acid Metabolism in Green Plants

“…Under experimentally imposed conditions, acid accumulation may continue for longer than a summer's night. Malic acid is often predominant among the acids which accumulate; but not inconsiderable amounts of other acids, for example, citric and isocitric acids in Bryophyllum (Pucher, Leavenworth, Ginter & Vickery, 19476, c), may be found at the end of a dark period.…”