Oedema, a physiological disorder, affects several cultivars of ivy geranium [Pelargonium peltatum (L.) L `Hér. ex Ait) when grown in greenhouses. This study investigated the regulation of oedema on this crop using far-red radiation because these wavelengths inhibited the injury on Solanaceous sp. Plants were exposed to far-red radiation from Sylvania #232 far-red lamps on abaxial and adaxial surfaces of leaves. A far-red photon flux of 15 to 20 μmol·m-2·s-1 (700-S00 nm) was not effective in preventing oedema injury. A far-red abaxial treatment during the light period tended to reduce the amount of injury that developed when photosynthetic photon flux was low (130-170 μmol·m-2·s-1), but this inhibition of the injury was absent with higher photon flux. The results from these studies indicate the use of supplemental far-red radiation treatments in greenhouses would not be justified because adequate and consistent control of the injury on ivy geraniums was not achieved.
If the inline PDF is not rendering correctly, you can download the PDF file here.
Present address: Dept. of Horticulture, Michigan State Univ., East Lansing, MI 48824.