Repeated and Prolonged Drought Exposure Reveals Contrasting Hydraulic Management Strategies Used by Tolerant and Sensitive Genotypes of Sorghum bicolor

Abstract

Climate change-induced variations in temperature and precipitation negatively impact plant growth and development. To ensure future food quality and availability, a critical need exists to identify phenotypic and physiological responses that confer drought tolerance in agronomically important crop plants. In this study, two Sorghum bicolor accessions that differ in their pre-flowering responses to drought were exposed to cycles of drying and rewatering. Morphological, physiological, and histological traits were measured across juvenile and adult developmental stages. Our results suggest that induction of stomatal closure works to prevent hydraulic damage under drought conditions, particularly when morphological and histological adjustments are unable to compensate for this hydraulic risk. These findings demonstrate that morphology, histology, and physiology may work independently over developmental time to achieve a shared goal of regulating transpirational water loss to mitigate the risk of xylem embolism.