Breeding Resilience: Using Physiological Traits to Select Heat-Tolerant Potato

Heat stress is a major limiting factor in potato (Solanum tuberosum L.) production, negatively impacting physiological processes and yield. Understanding genotypic responses to high temperatures is crucial for breeding heat-tolerant cultivars. This study aimed to identify the physiological and yield traits associated with thermal tolerance in potato genotypes. Fifteen potato genotypes from the EMBRAPA breeding program were evaluated. Plants were grown under controlled conditions for 30 days, followed by a 14-day heat stress period (supraoptimal temperature, 24 to 34^oC). Gas exchange and chlorophyll fluorescence variables were measured on the final stress day. Plants then returned to control temperature until harvest at 75 days, when yield traits were assessed. Data were standardized (z-score) and analyzed using hierarchical clustering and Principal Component Analysis (PCA). Results showed wide physiological divergence, indicating distinct adaptive strategies. Cultivar Granola and the advanced clone C1750-15-95 excelled with high photosynthetic efficiency and productivity. Clones C2514-05-06 and MB51-02 displayed strong photoprotective capacity, while cultivars Achirana and Pukara prioritized reproductive investment. PCA explained 66.1% of the total variance, highlighting photosynthetic efficiency and yield as primary discriminators. Genotypes that maintained balanced carbon assimilation, photochemical efficiency, and energy dissipation showed greater thermal resilience, providing promising physiological indicators for breeding heat-tolerant potato cultivars.