A synergistic effect of 2-ethyl-l-isopropoxycarbonyl-3-(4-tolylcarbamoyl) isourea with gibberellic acid on growth of rice seedlings

2-Ethyl-1-isopropoxycarbonyl-3-(4-tolylcarbamoyl)isourea [EITIU]stimulated both shoot and root growth of rice seedlings. Gibberellicacid [GA]-induced shoot elongation was further stimulated byEITIU, and the combined application of both compounds was shownto be distinctly synergistic. A similar synergistic action wasobserved in the growth of rice mesocotyls in the dark. The inhibitionof root growth caused by GA was overcome by combination withEITIU. The growth-stimulating activity of EITIU was not observedin lettuce hypocotyls. ¹ This paper is Part I in the series "Plant growth-regulatingactivities of isourea derivatives and related compounds." (Received February 7, 1976; )