Potassium Deficiency and Excess in Guayule. Ii. Cation-Anion Balance in the Leaves

Abstract

In many plants the potassium contained in the tissues is almost completely water soluble (3,15,16, 18, 19,32) It is generally supposed that much of the potassium present in plants is in the form of salts of organic acids and that these acids and their salts constitute principal components of the buffer systems. A relationship between the total organic acids and the excess of cations over inorganic anions in tobacco leaves of different ages and base composition was shown by PUCHER, VICKERY, and WAKEMAN (22). PIERCE and APPLEMAN (21) grew several species of plants in the same nutrient medium and showed a general correlation between the excess of cations and the total organic acids. In these correlations, however, were ineluded both soluble and insoluble constituents, and variations in insoluble oxalate and calcium contributed much to the variations in the total bases and organic acids. ULRICH (33) has shown that the total organic acid content of sap expressed from barley roots may be varied by unequal absorption of cations and anions from the solution. An absorption of cations in excess of anions results in an in-

Effects of Potassium Deficiency and Excess Upon Certain Carbohydrate and Nitrogenous Constituents in Guayule

“…When guayule leaves from the intermediate potassium treatments are used as a basis for comparison, high potassium leaves were relatively high in citric acid (9). Malic acid did not accumulate in high potassium leaves.…”

“…These workers have also shown that of the total free reducing sugars, the amounts of free nion-fructose sugars are always greater than the amounits of free fructose in spite of the fact that the chief reserve carbohydrates in guayule are polymers of fructose, levulins and inulin. The coniditions of the present experiment were not conducive to large accumulations of inulin, or higher polymer levulins, insofar as the experiment consisted of a phase of rapid growth.So far as the writers are aware, no detailed study has been made of the nitrogenous fractions in guayule.Effects of potassium supply upon growth responses and mineral contents of guayule plants and upon cation and inorganic and organic aniion contents of the leaves have been reported (8,9). In this paper are considered carbohydrate and nitrogenous fractions in tissues of the same plants.…”

“…Effects of potassium supply upon growth responses and mineral contents of guayule plants and upon cation and inorganic and organic aniion contents of the leaves have been reported (8,9). In this paper are considered carbohydrate and nitrogenous fractions in tissues of the same plants.…”

Organic Acid Metabolism and Ion Absorption in Roots

“…It is possible that some anion other than an organic acid radical is involved. For example, Cooil (5) has shown that bicarbonate in guayule leaves can function in cation balancing. In any event, this would not explain the disproportionate increase of malate over total organic acid.…”

“…Since roots may absorb cations and anions at unequal rates from single salt solutions, they must therefore have at their disposal mechanisms for maintaining cation-anion equivalency. In recent years, the role of organic acid metabolism in relation to the mainteilance of cation-anion balance have been investigated by Pucher, Vickery and Wakeman (15), Ulrich (17), Overstreet, Broyer, Isaacs and Delwiche (11), Pierce and Appleman (13), Burstrom (2), Cooil (5), and others.…”