Growth and gravireaction of maize roots treated with a phytotropin.

Effects of the phytotropin 1-(2'-carboxyphenyl)-3-phenylpropane-1,3-dione (CPD) on growth and gravireaction of intact roots and apical root segments of Zea mays L. cv LG-11 were analysed. It is concluded that the compound acts through sites of action in the extension zone and/or the root cap. The nature of the effects is consistent with the proposal that phytotropins may inhibit the gravitropic response by interfering in some way with the movement or action of the growth substance(s) emanating from the root cap.