Seeds saved by farmers may be infected with microbes that can induce diseases on the seedling and the crop. This can affect seed germination and may be transmitted from seed to seedling to plant.
Seed treatment prevents and controls seed-, soil-, and air-borne diseases. It improves germination, vigor, and productivity.
The following methods are used to treat seeds:
Many varieties have a dormancy period where germination levels are low. Several treatments can be used to break dormancy and improve seed growth.
- Expose seeds to high temperatures (40−42°C) for 1−2 days prior to sowing.
- Seed priming - Soak seeds for 4−8 hrs and re-dry prior to sowing. Seeds must be sown within 1−2 days after priming.
- Pre-germination - Submerge seeds in water for 12−24 hrs or until small shoots appear at the end of the seed. In colder weather, seeds may need to be soaked for 36−48 hrs. Drain and dry the seed in bag for 24 hrs in a shady area where air can circulate around the bags. If bag temperatures exceed 42°C, some seeds will be damaged. Broadcast or drum seed before the roots exceed 5mm in length. When calculating the planting rate, allow for expansion of 10-30% in seed weight.
Pre-germinated seeds cannot be sown through a drill seeder.
This is for N fixation by rice seedlings.
Use 1 g of Azospirillum sp. inoculant (as a powder) per kg of seed and mix with primed wet seed just before sowing.
Fungicide seed treatment
This method is rarely used in Asia.
- Dissolve 3 g fungicide (e.g., Benlate + Mancozeb or Arazone red alone) per kg seed in 5 ml water inside a plastic bag or plastic bottle.
- Distribute fungicide slurry about the walls of the container.
- Place seed in container, seal, and shake to coat seed uniformly with fungicide slurry.
- Wear protective equipment and follow appropriate safety procedures.
||Cleaning out unfilled seed
||Good filled seed under water
||Sowing seed in seed bed
||Manually seed sorting