This study evaluated the morphological and biochemical responses of potato genotypes to polyethylene glycol (PEG)-induced osmotic stress conditions. Using different concentrations of PEG solution assessed the adaptive response of genotypes in stress conditions. All potato genotypes exhibited reduced root and shoot length, a smaller leaf size, and decreased levels of photosynthetic pigments (chlorophyll a and b and carotenoids) under PEG treatments. However, an increase was evident in key indicators of oxidative and osmotic stress such as malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and proline levels. Among the tested cultivars, Telman showed the highest sensitivity to PEG-induced stress, while the cultivar Ugur maintained relatively stable productivity and exhibited adaptive traits. Despite considerable initial growth, the cultivar Vagif displayed a weaker adaptive response under prolonged stress conditions. A significant negative correlation was notable among the proline, MDA, and pigment contents, while a positive correlation was between the stem diameter and pigment levels. Among the traits, the highest coefficients of variation revealed genotypic differences in stress responses. The results enunciated that PEG-induced osmotic stress affects the physiological traits differently across the genotypes, providing valuable insights for identifying drought-tolerant potato cultivars. The findings provide a sound base for future breeding programs aimed at developing drought-resistant potato cultivars.

Keywords: Potato (S. tuberosum L.), polyethylene glycol, malondialdehyde, proline, hydrogen peroxide, photosynthetic pigments, morphological and biochemical traits

Key findings: PEG-induced osmotic stress caused significant morphological and biochemical variations in potato (S. tuberosum L.) genotypes and revealed genotypic differences in drought response. The cultivar Ugur exhibited relatively stable adaptive traits, while the cultivar Telman was highly sensitive, and the genotype Vagif showed limited long-term tolerance. The results can provide a greater support in the selection of drought-tolerant potato genotypes