Abstract: Alfalfa is an excellent legume with strong environmental adaptability. Leaf nutrient resorption is an important mechanism to improve nutrient use efficiency and enhance environmental adaptability. It directly affects the nutrient concentration, and consequently, the stoichiometric ratio of elements in alfalfa. Many studies have focused on the nutrient resorption and ecological stoichiometric characteristics of alfalfa, but few have focused on the relationship between nutrient resorption and stoichiometric ratios. To explore this relationship, we measured the concentrations of carbon, nitrogen, phosphorus, and potassium in the mature and senescent leaves of seven alfalfa cultivars. Then, the characters and the relationships between resorption (including resorption efficiency and resorption proficiency) and stoichiometry were analyzed. It was found that the average nitrogen, phosphorus, and potassium resorption efficiencies of alfalfa were 42.7%, 42.4%, and 52.1%, respectively, lower than those of global terrestrial plants (62.1%, 64.9%, and 70.1%, respectively). On the basis of the relationship between nutrient resorption and stoichiometric ratios, we concluded that the growth of alfalfa stands was limited by phosphorus in our study region. The leaf resorption efficiencies were positively correlated with the stoichiometric ratios in senescent leaves, but the opposite conditions were detected in the mature leaves. Thus, there is a close link between nutrient resorption and stoichiometric ratios, and this relationship is significantly affected by the growth status of the leaf (mature vs. senescent).

Key words: variety, ecological stoichiometry, alfalfa, nutrient resorption