Sexual Dimorphism in Nitrogen Allocation Patterns of Fraxinus velutina Torr. Across Developmental Stages

This study investigates the effects of gender and developmental stage on photosynthetic nitrogen allocation in 10-year-old Fraxinus velutina Torr. focusing on photosynthetic nitrogen and leaf nitrogen. The results reveal significant differences in photosynthetic nitrogen allocation patterns between genders and developmental stages (p < 0.05 for gender, p < 0.01 for developmental stages). Male trees generally exhibit higher photosynthetic nitrogen use efficiency (PNUE) and photosynthetic rate (Pphot) than female trees. However, female trees allocate more nitrogen to photosynthetic processes (Rubisco and bioenergetics) during fruit expansion to compensate for reproductive costs. This study highlights that gender and developmental stage influence leaf nitrogen partitioning and PNUE, with distinct nitrogen requirements for males and females across developmental stages.