This experiment was performed to investigate the effect of foliar application of amino acids on improving biochemical properties and yield evaluation of the effect of drought stress on pistachio, cv. Shahpsand in Damghan city during 2019 and 2020. Statistical analysis was conducted as a factorial split-plot based on a randomized complete block design (RCBD) with three replications. The main factor was irrigation intervals (35, 55, and 75 days) and sub-factors were including asparagine and

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... ine amino acids at three levels (0, 150 and 300 mg L-1). The results showed that the irrigation interval had a significant effect on catalase, peroxidase, polyphenol oxidase, sodium, chlorine, potassium, proline, protein, relative water content (RWC), and yield at the level of 1% probability and the maximum content of catalase, peroxidase, polyphenol oxidase, chlorine, proline, and RWC were observed at 75 days irrigation interval but the highest yield and potassium were obtained at 35 days irrigation interval. Mineral concentrations of sodium (Na) and chloride (Cl), in leaves increased with increasing irrigation cycle however, the Potassium (K) concentration in leaves decreased. The highest Na concentrations and Cl were observed in 75 days, and the lowest was in 35days. The correlation coefficient between catalase and peroxidase was positive and the correlation between sodium and potassium was Negative, but the correlation between chlorine and protein was negative. Foliar application of amino acids increased plant yield and resistance to drought stress.