Study of the Atriplex halimus response to drought and salinity stress in the seedling stage

                      In order to study effect of the various levels of drought and salinity stress (0, -4, -8, -12, -16 bar) on morphological, physiological and biochemical traits of Atriplex halimus in seedling stage under hydroponic culture, two separated experiments were conducted as completely randomized design in three replications in hydroecology laboratory of Gonbad Kavous University in 2013. Results showed that drought and salinity stresses had a significant effect on traits of root and stem length, root and stem dry weight, chlorophyll a, b and total as well as total phenols of A. halimus. According to the results, root lengh and stem dry weight of A. halimus significantly were increased under -4 bar of drought stress as compared to control. In return, these traits in higher concentrations of drought stress significantly decreased. Concentration of -4 bar of salinity also had a stimulation effect on the stem dry weight of A. halimus. In return, content of chlorophyll a, b and total pigments of A. halimus were decreased in all experimental treatments of drought and salinity stress. The highest decrease effect was obtained in the treatment of -16 bar. Total phenols content of A. halimus was increased with an increase of concentrations of drought and salinity stresses. This study showed that despite increase in total phenols under studied stresses and its role as non-enzymatic antioxidant, total chlorophyll and morphological traits in various concentrations also showed a decreasing trend. This indicates high drought and salinity stress as well as unsufficient of phenolic compounds in response to stress.