Starch Hydrolysis in Bean Leaves Following Spraying with Alpha Naphthalene Acetic Acid Emulsion

A 1 per cent naphthalene acetic acid-lanolin and water emulsion was sprayed on the upper surfaces of attached bean leaves. The digestion of starch and accumulation of sugars during a period of darkness or low light intensity and the rate of accumulation of sugar and starch during a period of illumination were studied by means of quantitative chemical determinations made at intervals following treatment. 2. The percentage of starch and dextrin in leaves sprayed with naphthalene acetic acid emulsion and placed in darkness decreased more rapidly than did that of control leaves. Noticeable differences, however, were not apparent for several hours after treatment. The percentage of sugar in leaves sprayed with the acid emulsion and placed in darkness increased during that period following treatment when starch digestion was most rapid, but later decreased as the starch reserve was depleted; finally reaching a value approximately equal to that of untreated leaves. 3. Leaves that had been depleted of sugars, starch, and dextrin by being kept in the dark and subsequently sprayed with naphthalene acetic acid emulsion and then placed in natural daylight accumulated less sugar, starch, and dextrin during the period of illumination than did comparable untreated leaves.