The effects of nitrogen and phosphorus fertilization on nutrient resorption in female and male Populus cathayana

Nutrient resorption from senescing leaves (before abscission) prolongs nutrient residence time within plants and enhances nutrient recycling, playing a crucial role in plant survival and growth. While several studies have documented nutrient resorption responses to nitrogen or phosphorus fertilization, the combined nitrogen and phosphorus fertilization was limited, particularly in dioecious plants. This study investigated the effects of nitrogen and phosphorus fertilization, as well as combined nitrogen and phosphorus fertilization, on biomass accumulation and allocation, nutrient resorption, photosynthetic nitrogen and phosphorus use efficiencies, and leaf ecological traits in female and male Populus cathayana . Nitrogen and phosphorus fertilization enhanced biomass accumulation and photosynthetic capacity in both sexes, while reducing the root to shoot ratio and nitrogen (NRE) and phosphorus (PRE) resorption efficiencies. Furthermore, NRE of both sexes exhibited a negative correlation with total biomass but a positive correlation with root to shoot ratio. NRE in males was positively associated with leaf thickness, leaf mass per area, and leaf vein density, while PRE in female plants exhibited a positive correlation only with leaf vein density. Additionally, photosynthetic nitrogen‐use efficiency in female plants decreased with increasing leaf thickness, leaf mass per area, and leaf vein density. Whereas, photosynthetic phosphorus use efficiency in both sexes showed positive correlations with these leaf traits. These findings found that nutrient resorption may be regulated by biomass accumulation and allocation, leaf ecological traits, and photosynthetic nitrogen and phosphorus use, enhancing our understanding of the plant nutrient acquisition and utilization mechanism.