Relation Between the Chlorophyll Content and Paleness of Gibberellic Acid-Treated Leaves

The rate of chlorophyll synthesis as a function of lime was examined in plants of Hordeum vitlgare L. cultivated in Knop solution containing 1 mg/1 GA₃. The action of concentration on the relations of chlorophyll components was investigated in GA₃ solutions of five different concentrations. The relations of total chlorophyll contents, including those of the a and b components, were determined from ethanol and aqueous acetone extract at various periods of treatment, at the same moment but with different concentrations of GA₃. A significant difference is noted between the chlorophyll contents of the GA₃ treated plants and those of the control. The chlorophyll contents of treated plants are decreasing. The difference increases with raising GA₃ concentration. The components were separated on thin layer with the partition method, and the spots were eluted. The density was measured with a spectrophotometer. Among the yellow components in the treated plants, the carotenes (α and β carotenes) increase as compared with the control plants. The total quantity of xanthophylls (lutein, zeaxanthine, lutein-5, 6-epoxide, violaxanthine and neoxanthine) almost equals the xanthophyll amount in the control plants; there is no significant difference. The paleness of leaves treated with GA₃ is provoked by the quantitative change of pigment components; the chlorophylls o and b decrease, the xanthophylls remain unchanged and the carotenes increase.