Phosphorus Metabolism of Trifolium Hirtum All. As Affected by 2,4-Dichlorophenoxyacetic Acid and Gibberellic Acid

It has been suggested by several investigators (3, 13, 17) that an important site of action of 2,4-dichlorophenoxyacetic acid (2,4-D) might lie in phosphorus metabolism. In early studies of phosphorus in 2,4D-treated and untreated bean plants (12), inorganic phosphorus was observed to be generally higher in treated plants. In experiments with sunflower plants (2) an increase in relative weight of inorganic phosphorus and a decrease in other fractions were observed when aerial parts were sprayed with 2,4-D. Wlhere 2,4-D was applied to the soil there was a decrease in weight of acid soluble phosphorus, including inorganic phosphorus, and a simultaneous increase in nucleo-proteins. In the leaves of young cranberry bean plants treated with 2,4-D (14), acid soluble, alcohol soluble and nucleic acid phosphorus were lowered somewhat in the leaves, but nucleic acid phosphorus was doubled in the stems. In studies of phosphorus uptake by bean plants (6). leaves of plants gr6wn in solution culture containing p32 after 2,4-D treatment picked up less phosphorus than the controls. Marked differences were shown between leaves and stems in regard to phosphorus uptake and distribution. Studies of the effect of gibberellic acid on plant metabolism have been scanty (15), and its effect on phosphorus metabolism has not been reported. It has been demonstrated (18), however, that phosphatase activity is increased in the leaves and stems of bean plants by gibberellic acid treatment. Total carbohydrates have been observed to increase in stems and petioles of gibberellic acid-treated cotton plants (5), but the highest rate used in the study was inhibitory to growth. The growth promoting levels of gibberellic acid caused much more change in the petioles and stems than in the leaves. This paper presents the results of a study of the effect of 2,4-D and gibberellic acid on certain aspects of phosphorus metabolism in young rose clover plants. It will be shown that both 2,4-D and gibberellic acid cause rapid and marked changes in the proportions of phosphorylated constituents in the plants and that