Effect of salicylic acid on organic osmolite accumulation and antioxidant activity of Nitraria shoberi L. under drought stress conditions

Abstract: Salicylic acid is a phytohormone with phenolic nature which has been proved its role in increasing plant resistance to biotic and abiotic stress in several studies. This study was performed in order to investigation of interaction between 0, 0.5 and 1.5 mM concentrations of salicylic acid, as a seed pretreatment and different levels of drought stress (100, 75, 50 and 25 percent of field capacity) on the proline and soluble carbohydrates accumulation and the catalase and peroxidase activity in Nitraria shoberi. Data analysed after 21 days of drought stress exerting on 45-old days seedlings showed that the carbohydrate content increased significantly about 50% and proline as much as 123% in moderate stress by high concentration of SA. But with the increase in water stress levels, was reduced the rate of this effects, insofar as the severe drought, SA could not to make a significant positive difference with the control samples. These results might be due to activation of metabolic consumption of these substances to form new cell constituents, as a mechanism to stimulate growth and or triggering other mechanisms of resistance by SA and no need to overproduction of this the substance. On the other hand SA causes 66% inhibition in the catalase activity and 50% stimulation in peroxidase activity. This event can lead to an increase of H2O2, which it involved in resistant as a signal molecule and also used for peroxidase activity as a precursor of lignin production and development of resistance in drought condition.