Abstract:To find out the distribution characteristics of major phenolic acids and coumarins in 18 alfalfa (Medicago sativa L.) varieties from different testing fields, the contents of these substances in plant and rhizosphere soil were determined by HPLC method. The coumarins and major phenolic acids in plant and rhizosphere soil were extracted using ASE 350 accelerated solvent extractor, and the extracts were stored at 2℃. After filtered through 0.45 μm organic filtration membrane, the autotoxins contents in the extracts were determined by HPLC. Results showed that the contents of coumarin, ferulic acid, chlorogenic acid and caffeic acid in 18 alfalfa varieties varied with plant varieties. Among these substances, the contents of coumarin and chlorogenic acid were dramatically higher than those of ferulic acid and caffeic acid. The differences of single autotoxin content among varieties were significant (P<0.05), and total contents of coumarin, ferulic acid, chlorogenic acid and caffeic acid varied with plant varieties as well. In addition, the average contents of phenolic acids and coumarins from Huining testing field were 4.01% higher than these from Wuwei testing field. In conclusion, the total contents of coumarin, ferulic acid, chlorogenic acid and caffeic acid were significantly different among various alfalfa varieties (P<0.05), and the total contents of these substances in alfalfa plant were remarkably different from those in rhizosphere soils.