Modification of 2,4-dichlorophenoxyacetic Acid movement in bean petioles by light.

There have been several reports of light effe-cts on the movement of growth-regulating substances in plants. Shen-Miller and Gordon (6) found that phototropically active blue light decreased the basipetal movement of IAA in Zca coleoptile sections. Similarly, Thornton and Thimann (7) *observed that blue light induced a transient decrease in the basipetal movement of IAA in Avena coleoptile tissues, but that red and far-red 'light were without effect. Naqvi and Gordon (5) found that white light significantly decreased the basipetal transport of IAA in Zea coleoptiles. During a class experiment at the University of East Anglia, England, Professor M. B. Wilkins found that light appeared to reduce the acropetal movement of radioactive 2,4-D in intact bean petioles. This in,vestigation was undertaken to determine whether light affects the movement of 2,4-D in green petiole sections of Phaseolhs nmultifloruis.