Phytohormones and light regulation of the growth habit in peanuts (Arachis hypogaea L.)

Diageotropic side branches in runner type peanuts assume anorthotropic position when grown in the dark but return to aplagiotropic postition when transferred back to light. The effectof light on the trailing habit of lateral branches depends onthe quality and intensity of the light taking place under blue+farred light, but not under blue alone. Light intensity below 28Kergs.cm^–2.sec^–1 changed the growth of the runner'slaterals from trailing to erect. Inhibitors of both GA and auxinactivity were higher in the laterals of runners than in thoseof the erects. Along with the change in the trailing habit bylow light intensity, a decrease in inhibitor level was observed.Gibberellin-like activity was smaller in both extracts and diffusatesof the growing tip of lateral branches than in the main axis.An inhibitor found only in lateral branches of runner type plantscould be detected in erect plants in the presence of auxin.The predominant factor controlling differences in the growthhabit of side branches of the erect and runner types is thepresence of an inhibitor; while, within each type, levels ofgibberellin seem to account for the different growth habit ofthe axis and laterals. (Received January 23, 1973; )