Inactivation of 2,4-D by Riboflavin in Light

(1 ALSTON AND BAKER (2) have established that riboflavin is a pho' toreceptor in the destruction of auxin by visible light by in vivo and in vitro experiments. Carrol (1) showed that riboflavin also reduced the activity of 2,4-dichlorophenoxyacetic acid (2,4-D). He believed that the reduction in activity occurred only in the presence of living plant material. The present studies using corn seedlings confirm the reduction in 2,4-D toxicity by riboflavin when the seedlings and substrate were illuminated. In addition, the inactivation of 2,4-D by riboflavin by light in vitro was also shown.