Coordinated Regulation of Photosynthesis, Stomatal Traits, and Hormonal Dynamics in During Drought and Rehydration.

, a woody oilseed species endemic to China, often experiences growth constraints due to seasonal drought. This study investigates the coordinated regulation of photosynthetic traits, stomatal behavior, and hormone responses during drought-rehydration cycles in two cultivars with contrasting drought resistance: 'CL53' (tolerant) and 'CL40' (sensitive). Photosynthetic inhibition resulted from both stomatal and non-stomatal limitations, with cultivar-specific differences. After 28 days of drought, the net photosynthetic rate (P) declined by 26.6% in CL53 and 32.6% in CL40. A stable intercellular CO concentration (C) in CL53 indicated superior mesophyll integrity and antioxidant capacity. CL53 showed rapid P recovery and photosynthetic compensation post-rehydration, in contrast to CL40. Drought triggered extensive stomatal closure; >98% reopened upon rehydration, though the total stomatal pore area remained reduced. Abscisic acid (ABA) accumulation was greater in CL40, contributing to stomatal closure and P suppression. CL53 exhibited faster ABA degradation and gibberellin (GA) recovery, promoting photosynthetic restoration. ABA negatively correlated with P, transpiration rate (T), stomatal conductance (G), and C, but positively with stomatal limitation (L). Water use efficiency (WUE) displayed a parabolic response to ABA, differing by cultivar. This integrative analysis highlights a coordinated photosynthesis-stomata-hormone network underlying drought adaptation and informs selection strategies for drought-resilient cultivars and precision irrigation.