The contribution of the morpho-physiological parameters of leaves and tubers of 22 potato varieties ( Solanum tuberosum L.) to the formation of yield under conditions of insufficient soil moisture and high air temperatures is studied. Discriminant analysis found that the stomata size (12%), chlorophyll content (10%), number of tubers (29%), and average tuber weight (21%) determined the gradation of plants by yield. The specific surface density of leaves (38%), the content of chlorophyll (13%) and carotenoids (13%), and the leaf area (12%) made the greatest contribution to discrimination in relation to ecological plasticity. It is concluded that the number of stomata per unit area of the leaf, the specific surface density of the leaf, and the content of photosynthetic pigments are the key characteristics that contribute to both the high yield and the adaptive capacity of potatoes.