Biological scarification: Biological method for increasing the germination of seeds of Alfalfa (Medicago sativa L.)

Alfalfa (Medicago sativa L.) is one of the most common commercial crops and the world's main source of fodder production. However, fields that are sown with Alfalfa often remain 1/4 empty since only 30 - 40% of sown seeds germinate, resulting in sparse crops and considerably reduced green mass yield. Alfalfa cultivation does not reach its full potential due to its hard seed coat that prevents germination. Mechanical scarification helps to break the integrity of the hard seed coat and thereby increases their germination, but this method often damages the embryo. This study aims to increase the germination of Alfalfa seeds using a new biological method: biological scarification. A strain of aerobic cellulolytic bacteria 21N2 was isolated and selected from cellulose-containing substrates. Its main characteristics of strain were studied. Identification of the strain using the molecular genetic method was carried out and it was found that the strain belongs to the genus Bacillus. The strain Bacillus sp. 21N2 has high cellulase activity, fixed atmospheric nitrogen, and synthesized B vitamins. Inoculated seeds with bacteria increased their germination by 28 - 34%. The strain has high PGP-activity (plant growth promotion activity), increasing stem length by 3.2 - 3.6 times, root length by 2.0 - 2.7 times. The bacteria changed the hard coat of seeds: the fibrillary structure was destroyed, microcracks were formed, and a pronounced layering of the coat appeared. Degradation of the integrity of the hard coat makes it more accessible to seed germination. Therefore, biological scarification contributes to the transport of water and nutrients to the seed germ, which stimulates seedling growth.