Genotypic variation in sweet potato under drought: physiological, biochemical, and morphological insights
Abstract
Abstract Sweet potato is widely cultivated in tropical and subtropical regions due to its nutritional value and agronomic versatility. Although often regarded as drought-tolerant, the crop is vulnerable to water deficit, which negatively affects yield and storage root quality. Assessing and understanding how sweet potato genotypes respond to water deficit is essential for identifying drought-tolerant candidates and supporting breeding programs aimed at improving resilience in drought-prone environments. This study aimed to evaluate the physiological, biochemical, and morphological responses of sweet potato genotypes under water deficit, with the goal of identifying drought-tolerant genotypes and better understanding their responses to water deficit. A completely randomized design was adopted in a 2×20 factorial scheme with four replications. The first factor consisted of two irrigation regimes (20% and 100% of pot capacity), and the second of 20 sweet potato genotypes. Parameters related to chlorophyll fluorescence, biomass accumulation, water potential, gas exchange, biochemical markers, and secondary metabolites were evaluated. Results revealed considerable genotypic variability in response to water deficit. Drought stress affected physiological traits associated with photosynthetic performance and oxidative metabolism, although the intensity of responses varied among genotypes. Principal component analysis highlighted contrasting adaptive strategies involving physiological regulation, antioxidant responses, and root growth adjustments under drought conditions. Genotypes ‘Luiza’, ‘Canadense’, ‘CIP-420717’, ‘Maria Isabel’, and ‘CIP-440186’ exhibited superior performance and represent promising sources for drought-tolerance breeding in sweet potato. Their superior performance was associated with higher water use efficiency, maintenance of photosynthetic traits, and lower oxidative damage under drought conditions.