EXPOSURE WITH FAR-RED RADIATION FOR CONTROL OF EDEMA INJURY ON YALE IVY GERANIUM

Oedema, a physiological disorder, affects several cultivars of ivy ger anium [Pelargonium peltatum (L.) L 'Her. ex Ait) when grown in greenho uses. This study investigated the regulation of oedema on this crop us ing far-red radiation because these wavelengths inhibited the injury o n Solanaceous sp. Plants were exposed to far-red radiation from Sylvan ia #232 far-red lamps on abaxial and adaxial surfaces of leaves. A far -red photon flux of 15 to 20 mumol.m-2.s-1(700-800 nm) was not effecti ve in preventing oedema injury. A far-red abaxial treatment during the light period tended to reduce the amount of injury that developed whe n photosynthetic photon flux was low (130-170 mumol.ml-2.s-1), but thi s inhibition of the injury was absent with higher photon flux. The res ults from these studies indicate the use of supplemental far-red radia tion treatments in greenhouses would not be justified because adequate and consistent control of the injury on ivy geraniums was not achieve d.