The use of organic and chemical fertilizers as amendments of properties of soil can be one of the strategies to reduce the adverse effects of drought stress. The effect of potassium sulfate, compost, and biochar on leaf dry matter, gaseous exchanges, instantaneous and intrinsic water use efficiency (WUEinst and WUEi, respectively) of grapevines (Vitis vinifera L.) cultivar ‘Bidaneh-Ghermez’ evaluated under two conditions: without water stress condition (field capacity (FC)) and irrigation in 40% FC. The experiment was conducted in a factorial of random complete blocks experiment design in the greenhouse. The results showed that the interaction effect of water stress and fertilizers’ treatments was significant for photosynthesis rate, stomatal conductance, and WUEinst. Drought stress significantly reduced photosynthesis rate, stomatal conductance, and transpiration of grapevines leaf. Fertilizers’ application compensated drought stress. WUEinst was higher in organic treatments compared with chemical treatment. WUEi for fertilizers’ treatment in drought stress conditions was higher than those in unstressed conditions. The highest K+ concentration of grapevines leaf 1.77 and 1.60% was observed in biochar treatment under both unstressed and stressed conditions. The dry matter of grapevines leaf had no significant differences for all experimental treatments under unstressed conditions and potassium sulfate and biochar under stressed conditions. The dry matter of grapevines leaf for compost treatment was significantly lower than the above-mentioned treatments. According to the results of this research, could be concluded that the application of fertilizers especially biochar can be considered to reduce drought stress of grapevines cultivar ‘Bidaneh-Ghermez’.