Combined Effects of Potassium Supply and Growth Substances on Plant Development

Abstract

Effects at different levels of K nutrition of indoleacetic acid and of [alpha] naphthalene acetamide, applied individually in a series of concs. in the nutrient soln. to red kidney beans (Phaseolus vulgaris) grown in sand culture in the greenhouse, were studied by dry wt. detns. Differences were statistically analyzed for significance. With indoleacetic acid, increased dry wt. of total plant was obtained at concs. of 10-7, 10-8, and 109 but only when the K level was high relative to growth. There appeared no replacement of K by indoleacetic acid. No evidence was secured indicating earlier flowering or increased number of leaves owing to treatment by either growth substance. Naphthalene acetamide responses were similar at all K levels. Dry wt. of roots increased 34-58% at the 10-8 conc. of this growth substance, but only decreases in dry wt. of tops were obtained.