Autotoxicity Effects of Aqueous Extracts of Different Aged Alfalfa on Seeds Germination

Alfalfa(Medicago sativa L.) plants of different aged stands were collected from Qingyang and Dingxi,Gansu Province on the Loess Plateau.The effects of aqueous extracts from different plant parts on alfalfa seed germination were investigated using filter paper method.The results showed that the aqueous extracts from alfalfa plant had inhibitive effects on seed germination and seedling growth,and extract from alfalfa flowers had the strongest inhibitory effect.Aqueous extract from Qingyang 4-6 year stand had the strongest inhibitory effect to hypocotyl length in comparison with the aqueous extract from Qingyang 10 year stand.Radical length was relatively more sensitive than hypocotyl length to autotoxic alleochemicals.Hypocotyl and radical elongation of alfalfa were inhibited more by alfalfa extracted solution than the germination.For 4-6 year stand alfalfa,rotation should be adopted to overcome the autotoxicity effects.