Effect of Low Nitrogen and Sulfur Supply on Their Accumulation in the Cotton Plant

Abstract

1. Nitrogen and sulfur accumulation in the leaves, chloroplast fragments, and bark of cotton plants grown at deficient levels of the two elements were compared with those of plants grown at nondeficient levels of supply. The two deficiencies were alike in effecting lower concentrations of soluble S, protein N, and protein S, and higher concentrations of amino and amide N in the leaves. Chloroplastic protein N and protein S, and also chlorophyll, were reduced by both N and S deficiency. The proportion of the leaf's protein S in the chloroplasts was lower under N deficiency and higher with S deficiency than in the controls. Under conditions of S deficiency, nitrates and soluble organic N accumulated excessively in the leaves, in contrast to reduced accumulation of soluble sulfate and organic sulfur in the leaves of N-deficient plants. 2. Leaf color of N-deficient plants graded from yellowish-green in the bottom to green in the upper leaves, while the converse characterized S-deficient plants. From data on c...