Stoichiometric homeostasis of N:P ratio drives species-specific symbiotic N fixation inhibition under N addition

Introduction Symbiotic N fixation inhibition induced by supply to legumes is potentially regulated the relative and P availability in soil. However, specific responses of different legume species changes N:P remain unclear, must be better understood optimize symbiotic inputs under enrichment. This study investigated mechanisms which soil influence eight species, quantify inter-specific differences, demonstrate how these differences can determined stoichiometric homeostasis ratios (H ). Methods Eight herbaceous were grown separately outdoor pots treated with either no fertilizer (control), (14 g m -2 ), (3.5 ) or both fertilizer. Plant nutrients, characteristics, root biomass, non-structural carbohydrates (NSC), rhizosphere chemistry, mobilization, nodulation measured. Results addition enhanced mobilization but drove a loss biomass NSC via exudation compound (organic acid), especially so treatments without addition. also 2-14% 14-36% decline per plant addition, as result decreasing NSC. The positively correlated intact plants nodules, regardless additions. Discussion indicates that induce limitations for growth, stimulate at expense carbohydrate concentrations, reducing legumes. Legume had less ratio, such Lespedeza daurica Medicago varia maintained greater extent