Agricultural seeds are coated with metal compounds, but it's not just for making them “grow better” in a simplistic sense — it's part of a broader strategy to enhance germination, seedling vigor, and resistance to pests and disease. Here's a breakdown:
1. Micronutrient Coatings Seeds are often coated with metal-based micronutrients such as:
- Zinc (Zn)
- Manganese (Mn)
- Copper (Cu)
- Iron (Fe)
These help support early seedling development, especially in soils that are deficient in these elements. For example:
- Zinc is vital for enzyme function and hormone regulation.
- Manganese and copper help with photosynthesis and disease resistance.
2. Fungicidal and Bactericidal Treatments Some coatings include metal-based fungicides, such as:
- Copper sulfate
- Manganese ethylene-bis-dithiocarbamate (Maneb)
These are applied to reduce the risk of seed-borne and soil-borne diseases during germination.
3. Other Coating Components Besides metals, seed coatings may also include:
- Inoculants (beneficial bacteria like Rhizobium for legumes)
- Polymers and colorants (for handling, identification, and safety)
- Pesticides or insecticides (e.g., neonicotinoids—though controversial and restricted in many places)
4. Pelleting and Encrusting In high-tech seed treatments, coatings can make small seeds like lettuce or carrot easier to plant by increasing size and uniformity — this is where coating with minerals like lime or clay also comes in. |
