Effects of nitrogen and phosphorus supply on growth rate, leaf stoichiometry, and nutrient resorption of Arabidopsis thaliana

Nitrogen (N) and phosphorus (P) availabilities affect plant growth and the balance of elements, yet how these plant traits respond to N and P supply remains unclear. We explored the effects of N and P supply on the growth rate, leaf N and P concentration, and nutrient resorption of Arabidopsis thaliana in a greenhouse fertilization experiment. Relative growth rate increased with mature green-leaf N:P ratio (N:P-gr) when N-limited, but decreased with N:P-gr when P-limited, suggesting that the growth rate hypothesis might be related to the type of nutrient limitation. In N-limited A. thaliana, addition of P did not significantly affect the leaf N concentration. However, in P-limited A. thaliana, addition of N decreased the leaf P concentration. Addition of N increased P resorption efficiency, and addition of P stimulated N resorption efficiency. Consistent with the predictions of the relative resorption hypothesis, the difference in the proportionate resorption of N vs. P declined with increasing N:P-gr. Our results suggest that N and P jointly regulate growth rate, leaf stoichiometry, and nutrient resorption of A. thaliana, and highlight that the interacting effects of nutrients should be considered when predicting future responses of plant functional traits to global change.