Structural and functional alterations in radish plants induced by the phenylurea cytokinin 4-PU-30

Single treatment of expanding radish leaves with N₁-(2-chloro-4-pyridyl)-N₂-phenylurea (4-PU-30) lead to the stimulation of root cambial tissue activity and root growth. Leaf thickness, the volume of chlorophyll (Chl) containing cells per unit leaf area, starch content in the chloroplasts, and the Chl content increased simultaneously. These alterations were associated with increased leaf net photosynthetic rate and stomatal conductance in treated plants. This study was supported by the Bulgarian National Foundation for Scientific Researches (Contract B-413). 4-PU-30 was kindily provided by Prof. K. Shudo, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan. We wish also to thank Dr. T. Tsonev for valuable advises.