Abstarct: Two field experiments as randomized complete block design with three replications in Karaj and Shahriyar were conducted to study the ecophysiological and phytochemical responses of Chinese lantern to biostimulants under low irrigation conditions. Treatments were split-plot arrangement of 3 irrigation levels [complete irrigation (control); 75% (moderate stress) and 50% irrigation (intense stress)] in main plots, and foliar application of 5 amino acids [control, tryptophan, glycine, tyrosine and arginine (1 mg/L)] in sub-plots. The results of the analysis of variance indicated that in some cases the effect of few factors, and in other cases the effect of all factors were significant on all measured traits. Tyrosine and arginine intensified the activity of peroxidase enzyme under intense stress conditions of Shahriar, as compared to control; this was not true for proline. Under intense stress conditions of Karaj, the foliar application effect on proline was increasing when compared with control. Under 50% irrigation conditions of Shahriar, tyrosine, arginine, and glycine increased the lycopene amount to a level higher than control. This was not true under Karaj conditions, which indicates that the effect of these amino acids is undermined by climatic and edaphic conditions. The increasing effect of tyrosine on total dry weight was significant only under 50% irrigation conditions; the effect of other amino acids was positive under all irrigation levels. Under stressed- and non-stressed-conditions, tryptophan could promote the economic yield to a level higher than control; accordingly, application of this amino acid is recommendable.