ORGANIC ACIDS OF THE COTTON PLANT

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Abstract
The leaves of cotton plants frequently contain 20% of organic acid on the dry wt. basis. Successively lower concn. are found in the petioles, flowers, stems, roots, young bolls, seed kernels, and lint. Of the total organic acid malic tends to constitute 30-40%. Drought increases malic and decreases citric acid without change in the total acid. This transformation is reversible and apparently proceeds through some intermediate acid or acids included in the unidentified group. When grown on nitrate N the excess of inorganic bases over inorganic anions increased by 76 m.eq. per 100 g. relative to plants on ammonium N. The organic acids increased by 53 m,eq. and maintained the pH value of 5-5.6 characteristic of cotton leaves. Comparisons of the disappearance of the carbohydrates and inorganic acids from excised and attached leaves during 5 days in the dark indicate that carbohydrates are translocated and respired to 4 times as great an extent as are the organic acids. Other results indicate little or no respiration of organic acids until labile carbohydrates are nearly exhausted. Consistent correlations were not found between variations in the concn. of the organic acids and the sugars, starch, or soluble and insoluble N.