EFFECTS OF NITRIC-OXIDE AND OZONE ON SPRING WHEAT (TRITICUM-AESTIVUM)

The hypothesis that stress ethylene production could determine plant s ensitivity to ozone was tested with spring wheat (Triticum aestivum). The mechanism includes formation of radicals which induce peroxidative chain reactions. NO in the low ppb range could induce additional ethy lene production. NO was added to three ozone levels in order to invest igate its potential in enhancing ozone toxicity. Using malondialdehyde , ethane emission and activity of ascorbate peroxidase as indicators o f peroxidation reactions, no indications for the postulated interactio n was found. NO at low ozone concentrations induced effects on yield a nd physiological parameters similar to those of increased ozone concen trations, but this was not due to additional ethylene production. At h igher ozone concentrations no adverse effect of NO addition could he d etected.