<div>Background: Alfalfa crops are subject to intercalation when grown continuously on the same field, and autotoxicity appears to be another factor in this thinning. Alfalfa fields are often thinned out and have lower yields during consecutive production, and autotoxicity is increasingly found to be a major reason. Hence, Therefore, understanding the seed germination and seedling growth and physiological mechanisms of the alfalfa under continuous cropping system becomes important for sustainable the use of alfalfa grassland.&nbsp; 
 
Methods: The leaves, stem, root and rhizosphere soil of alfalfa (Medicago sativa L. cv ZhongMu No.1) were collected to determine the seedling growth germination index (GI) and vigor index(VI), physiological characters malondialdehyde (MDA), proline, Soluble sugar (SS), Soluble protein (SP), Superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). 
 
Result: The germination rate, germination potential, germination index (GI) and vigor index decreased with the increasing extract contents, particularly in leaf extracts. In the extract of plant and soil, the concentration of malondialdehyde altered indistinctly, while the contents of osmo-regulatory substances and the activities of anti-oxidative enzymes generally decreased. Furthermore, the extract increased the seedling length of alfalfa and GI was negatively correlated with seedling growth characteristics.</div>

Effects of Continuous Cropping on Seed Germination and Seedling Growth, Physiological Characters of Alfalfa