研究了盆栽和田间苜蓿的固氮作用,测定了在无氮介质中生长的7种紫花苜蓿和1种白三叶固氮过程的氮同位素分馏效应(β值),评估了不同生长季节的不同品种苜蓿茎叶和生长在不同条件下不同牧草茎叶的δ~(15)N值的变化,用~(15)N天然丰度法、~(15)N同位素稀释法和全氮差值法估算了苜蓿的％Ndfa(苜蓿植株全氮中来自空气氮所占的比例),并比较了各方法的精度。 Nitrogen fixation was studied in potted and field alfalfa. The nitrogen isotope fractionation (β value) of seven alfalfa cultivars and one white clover growing nitrogen-free medium was measured, and the effects of different varieties of alfalfa The δ ~ (15) N values ​​of stems, leaves and leaves of different forage cultivated under different conditions were estimated by ~ (15) N natural abundance method, ~ (15) N isotope dilution method and total nitrogen difference method The% Ndfa for alfalfa (proportion of total nitrogen in air from alfalfa plants) was compared and the accuracy of each method was compared.