The Effect of Gibberellic Acid on Enzyme Activity and Oxygen Uptake in Bean Plants (Phaseolus Vulgaris)

Gibberellic acid, a tetracyclic dihydroxylactonic acid, C1H2206, produces marked shoot elongation in many plants (2, 3, 11, 12, 13). Unlike other auxins, its stimulation of growth of intact plants often results in substantial increases in height, and in fresh and dry weights (2). Brian (2) noted that the ash, nitrogen, phosphorus, potassium, total soluble carbohydrates, and carbon increased in the shoots and decreased in the roots of gibberellic acid treated wheat and pea plants. For the entire plant there was a net increase in these constituents. In rice seedlings Yabuta et al (13) found no difference in the ash, reducing sugar, total nitrogen, or total weight, but the treated plants contained less chlorophyll and total sugfar. Wittwer et al (11) recently demonstrated that gibberellin will induce parthenocarpic fruit development in the tomato and earlier flowering in several crops. Kato (5) has reported significant increases in oxygen and water uptake of pea stem sections treated with gibberellin. Little information has been reported on the effect of gibberellic acid on plant metabolism; therefore, certain enzyme systems and rates of oxygen uptake of intact bean plants treated with gibberellic acid were studied. Bean seeds var. Blue Lake (Stock no. 42335, Roger Bros. Seed Co., Inc., Idaho Falls, Idaho) were sown in quartz sand in a greenhouse. After 8 days