Seed Dormancy and Germination in Alfalfa (Medicago falcata L.)

Background: Medicago falcata L. (M. falcata L.) is widely distributed in Xinjiang and Inner Mongolia, which is a significant source of resistance genes. Its seeds have a high level of physical dormancy (PD). The current study aimed to study the dormancy characteristics, water absorption characteristics and methods for releasing hard seeds of M. falcata L., to reveal the the relationship between seed coat structure and water absorption and to understand the dormancy characteristics, which can provide theoretical basis for seed dormancy and seed biology research. Methods: Seed germination rate (GR), absorption, germination inhibitor activity and initial site of water entry into seeds were measured to investigate the causes of seed dormancy. Treatments to break dormancy included: (1) sandpaper sanding, (2) ultrasonic treatment for 30 min after sandpaper sanding, (3) 98% sulfuric acid immersion (5,10, 20, 40, 60 and 120 min) and (4) hot water immersion at different temperatures (50, 60, 70, 80 and 90 degrees C) for 10 min, 20 min and 30 min. Result: The results showed that the hard rate of untreated seeds was 99.33% and the hard rate after the seed coat was scratched was 1.33%. Based on the inhibitory activity test of M. falcata L. seeds, high concentration seed extract has an inhibitory effect on the growth of other seeds. The toludine staining test showed that the hilum and microscope are the initial and main parts for seed water absorption. The germination rate of seeds after soaking in 98% sulfuric acid for 40 minutes and ultrasonic treatment with sandpaper for 30 minutes is higher than 94%, which is an effective method to relieve the PY of M. falcata L. seeds.