Seeds of wheat, cabbage, basil and radish were successfully encapsulated in calcium alginate according to a protocol allowing the gelation of the polymer from the surface of seeds outward (inside-outside). A careful choice of type of alginate coupled with heat treatment of the sodium alginate solution allowed production of encapsulated seeds that gave soil emergence percentages not different from untreated seeds in basil, cabbage and radish. Encapsulated wheat seeds never showed emergence percentages similar to untreated seeds. Alginates resulting in the best performances were Sigma 3500 (basil), Sigma 250 (cabbage), Carlo Erba FU (radish and wheat). Seeds were immersed in a CaCl2.2HO 2M solution for 30' at room temperature. After drying, treated seeds were immersed for 20' in a stirred 1% (w/v) sodium alginate water solution previously heat treated at 120degreesC for 15'. Encapsulated seeds were then immersed in distilled water on a magnetic stirrer for 20'. Coated seeds (pellets) were dried for 24 hours under airflow at 30degreesC on a single layer of Myracloth(R). Addition of bran and chitin at 12.5 gl(-1) to the pellets did not alter seedling emergence, whereas addition of these co-formulants at 25 gl(-1) prevented pellet growth around basil seeds. Storage of pelletted cabbage and basil seeds at room temperature did not significantly modify germination percentage after 30, 60 and 90 days. Suggested protocol deploys an unusual method (inside-outside gelation) to encapsulate seeds in alginate beads. This method is technically simple since dry CaCl2 treated seeds are dropped in a sodium alginate solution and it allows the production of dry coated seeds easy to store and to sow.
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