CULTIVAR EFFECTS ON RADISH SENSITIVITY/ RESISTANCE TO CHRONIC ETHYLENE EXPOSURE

摘要

The Radish Assimilation in Spaceflight Testbed Atmospheres (RASTA) experiment is being developed to determine the effects of volatile organic compounds on growth and development in microgravity. Three cultivars of Raphanus sativus L; Sora, Cherry Belle and Cherry Bomb Hybrid II, were evaluated for resistance to ethylene effects. Radish will be used as an indicator species to determine effects of biogenic and anthogenic volatile compounds within the International Space Station on plant growth. Radishes were selected as a candidate crop because of their short stature (<15 cm), rapid growth cycle (14-24 days) and sensory characteristics (color, flavor and texture). The radish cultivars were exposed to ethylene concentrations of 0, 250 and 750 ppb for 21 days, which corresponded to control, maximal, and phytotoxic concentrations in Cherry Belle radish (Eraso et al., 2002). Sequential harvests at 7, 14 and 21 DAP were made and growth analysis performed. All three cultivars exhibited characteristic symptoms of ethylene exposure, such as stern swelling, height reduction, and severe leaf epinasty at both 250 and 750 ppb concentrations of ethylene. Cherry Belle was more sensitive to ethylene exposure than cultivars Sora and Cherry Bomb, which were more resistant than Cherry Belle at a concentration of 250 ppb. Ethylene affected harvest index of Sora at both 250 and 750 ppb concentrations more than either Cherry Belle or Cherry Bomb. Additional evaluations are required to determine the sensitivity and resistance of biologically active volatile organic compounds found in spacecraft for these cultivars.