EFFECTS OF POTASSIUM DEFICIENCY AND EXCESS UPON CERTAIN CARBOHYDRATE AND NITROGENOUS CONSTITUENTS IN GUAYULE

Abstract

Guayule plants were grown with low, intermediate or high levels of K supply in each of 2 series of treatments differing in supply of Ca and Na. Certain carbohydrate and nitrogenous fractions were detd. in several parts of these plants. Carbohydrate fractions were also detd. in parts of plants grown with or without K. Leaves from low K plants were high in reducing sugars. Old stems and roots of low K plants were low in levulins. In all parts of low K plants, reducing sugars were high when expressed as % of total carbohydrates. Condensation of fructose in leaves of low K and intermediate K plants appears more closely related to the ratio K/soluble Ca in the leaf tissues than to K concn. in these tissues. The significance of these results is discussed in relation to results from other plants in which other polysaccharides are products of hexose condensation. A possible scheme for the role of K is suggested. Amide and alpha-amino N fractions were highest in leaves of plants having the lowest K concn. Insoluble and soluble organic N fractions were at least as high in low K plants as in plants containing adequate K. High K plants contained less organic N and more nitrate N in their leaves than did plants of other treatments. The altered proportion of individual organic acids in leaves of high K plants is considered in relation to limited nitrate reduction.