Impact of Exogenous Ascorbic Acid on Antioxidant Activity and some Physiological Traits of Common Bean Subjected to Salinity Stress

The role of ascorbic acid as a key molecule antioxidant involves in biotic and abiotic stress has already been well described. Recent study indicates that it also participates in the detoxification of generated reactive oxygen species due to abiotic stresses. Thus, In order to study effects of salt stress and ascorbic acid on anti oxidant enzyme activity, chlorophyll content, lipid peroxidation and abscisic acid accumulation of bean an experiment was conducted. The exogenous application of ascorbic acid in nutrition solution of bean plants indicated chat later is involve in reduction of antioxidant enzyme activity and increase of resistance to salt stress. We observed that antioxidant enzyme activity increased due to salt stress and ascorbic acid via eliminating of reactive oxygen species decreased activities. Moreover, abscisic acid and lipid peroxidation were affected of salt stress. Increase of ascorbic acid concentration at 100 mM NaCl treatment prevented of lipid peroxidation and decreased generation of malondialdehyde as final product of peroxidation of membrane lipids. However, at high level of salinity. ascorbic acid did not significant effect on reduction of lipid peroxidation. Whereas, chlorophyll content decreased by reactive oxygen species. Ascorbic acid increased chlorophyll content at all of stressed and non-stressed treatments. Abscisic acid assay showed chat, accumulation of this hormone increased under salt stress treatments and raise of ascorbic acid concentration in nutrition solution of stressed plants prevented of abscisic acid accumulation, Our data provide strong support to the hypothesis that exogenous of ascorbic acid reduces the harmful effects of salinity and increases resistance to salinity in bean plant.