Different responses of biomass allocation and leaf traits of Dodonaea viscosa to concentrations of nitrogen and phosphorus

Aims The adjustment of leaf traits and biomass allocation is an important way for plants to adapt to environmental changes. Revealing the responses of biomass allocation and leaf traits of Dodonaea viscosa seedlings to nitrogen and phosphorus concentrations, is crucial to understand the adaptation strategies of D. viscosa under the changes of nitrogen and phosphorus.Methods Seedlings of D. viscosa were planted under nitrogen concentrations (3, 5, 15, 30 mmol·L^-1) and phosphorus concentrations (0.25, 0.5, 1, 2 mmol·L^-1) by sand culture. Plant height, base diameter, biomass allocation, leaf traits and their correlations were quantified.Important findings The results showed that high nitrogen concentration (30 mmol·L^-1) increased the height, diameter, leaf nitrogen concentration, and biomass accumulation of D. viscosa, and there were no significant differences of the traits under other concentrations (3, 5, 15 mmol·L ^-1). Compared with the high nitrogen level, other treatments significantly reduced the biomass accumulation and leaf nitrogen concentration, and significantly increased the root:shoot biomass ratio and nitrogen utilization efficiency. With the increase of phosphorus concentration, the biomass of D. viscosa increased significantly. Low phosphorus concentrations (0.25, 0.5 mmol·L^-1) significantly constrained the growth of D. viscosa, and the root:shoot biomass ratio and phosphorus utilization efficiency did not change significantly. Low phosphorus conditions increased the specific leaf area and the leaf:stem biomass ratio, and decreased leaf dry matter content significantly. Under the nitrogen treatment, leaf nitrogen concentration was negatively correlated with the root:shoot biomass ratio, while under phosphorus treatment, leaf nitrogen concentration was positively correlated with specific leaf area. Height, diameter and total biomass of D. viscosa were negatively correlated with the root:shoot biomass ratio, and positively correlated with leaf nitrogen concentration under the condition of nitrogen treatment, indicating that the adjustment of root:shoot biomass ratio and leaf nitrogen concentration played an important role in adapting to nitrogen limitation. However, under the condition of phosphorus treatment, height, diameter and total biomass were negatively correlated with specific leaf area, and positively correlated with leaf dry matter content, indicating that the adjustment of leaf structural traits was of great significance in adapting to changes of phosphorus. Our findings suggest that the biomass allocation, leaf traits and their relationships responded differently to changes in nitrogen and phosphorus, and the effects of nitrogen or phosphorus on plant traits should be discriminated in the future.