Starch Hydrolysis in Bean Leaves as Affected by Application of Growth- Regulating Substances

Lanolin emulsions containing various growth-regulating chemicals were sprayed on attached bean leaves and the plants were subsequently placed in darkness, together with controls. Quantitative analysis of the starch and dextrin content of the leaves showed that application of sprays containing indoleacetic, naphthaleneacetic, indolebutyric, indolepropionic, and naphthoxyacetic acids resulted in marked increase in the rate of starch digestion. Phenylacetic acid resulted in only a slight increase, while naphthalene acetamide had no noticeable effect. 2. Treatment of relatively old and mature leaves with these various chemicals either failed to stimulate, or inhibited to some extent, the hydrolysis of starch during a 12-hour period of darkness following treatment. 3. Application of these growth-regulating chemicals did not result in a noticeable increase in the rate of starch digestion in leaves kept at 62⚬-64⚬ or at 90⚬-92⚬, but was effective at 74⚬-76⚬ F. 4. The sugar content of leaves kept in darkness increased appreciably for a period of time following treatment with indoleacetic acid, a response previously observed in leaves treated with naphthaleneacetic acid.