Potato crop regularly faces water deficit and heat stresses which affect its yield and quality. Water deficit and heat waves can cause up to 60% and 30% of yield loss respectively. These stresses induce changes in the photosynthesis efficiency due, for instance, to stomatal closure or photosystem degradation. Drought stress, in our case, a period of water shortage coupled with a heat waves causes a decrease in An , Gsw and an increase in WUE . Lady Claire, the variety with the highest potential An, remain the variety with the highest An and Jule the variety with the lowest potential An, takes longer to recover during rehydration. The increase in WUE is particularly due to a decrease in Gsw more severe for Kennebec