Various methods can be adopted for seed preservation, depending on the environmental conditions required for seed storage. Seeds can be stored in the following ways:
1. Seed Storage Without Temperature and Humidity Control: This method involves storing seeds in buckets, sacks, balls, tins, or clay pots. It is effective during dry and cold seasons but may not be suitable for vegetable seeds. Fumigation or the use of insecticides is necessary to control pests. Seeds are dried in the sun and stored in the mentioned containers. Examples of seeds that can be stored using this method include pumpkin, squash, red cabbage, eggplant, and tomato. For commercial storage, seeds can be stored in clean, pest-free chat sacks or suitable seed storage warehouses.
2. Storage of Seeds at Room Temperature with Humidity Control: Dry seeds are stored in airtight containers, which is effective during wet seasons. Air-permeable tin, aluminum, glass, or plastic containers can be used. Alternatively, thick polythene bags or varnished/bitumen-coated earthen pots can also be utilized. Containers should be sealed to prevent air movement.
3. Seed Storage in Non-Humidity Controlled Freezers: These freezers are typically kept above 80% humidity and are used for storing agricultural products like potatoes and onions. Seed potatoes should be pre-cooled at 16-18°C for 24-48 hours before placing them in the freezer. The freezer temperature should gradually decrease to 4°C, with a relative humidity of 88-90%. The freezer door should be opened every three days to allow fresh air in and prevent oxygen deficiency, which can cause physiological disorders in the seeds. It’s recommended to turn the seed bags at least twice a week during storage.
4. Seed Storage in Moisture-Controlled Cold Storage: This type of cold storage is used for storing horticultural fruit seeds. The temperature of the freezer is typically kept at 10°C, and the relative humidity should not exceed 50%. Seeds stored in these conditions can remain alive and fresh for 3-8 years. However, setting up and operating such cold storage facilities can be expensive.