Seed coating

seeds coated with blue green and red seed coatings

What is seed coating?

In a nutshell; seed coating is spraying a synthetic polymer on a seed resulting in a thin cover. The coating sticks to the seed and prevents loss of nutrients, plant hormones and also prevents fungicides. Some of the newest seed coatings are temperature dependent and water resistant. This coating is generally used to control the timing of germination and seedling emergence.  A seed coating is actually a form of enhancement.

Nowadays, more and more enhancements are added to the seed. Therefore, it needs a strong and reliable coating to keep it all in. Seed coatings can be used for:

  • Delaying germination;
  • Enhancing optimal crossing of genes of hybrid seeds;
  • Speeding up plant cycles;
  • Increasing storing time;
  • Protect seeds from environmental stress;
  • Keeping precious nutrients locked in;
  • Product identification (available in many different colours!).
Seed coating on different types of seeds in many colours

Seed coating is available in many different colours

Seed coating in India

According to a September 2014 report on seed coatings from Markets and Markets, the existing seed coatings market is valued at $993.84 million and is projected to reach $1.4 billion by 2019, growing at a compound annual growth rate of 7.5 percent from 2014 to 2019.

The seed coating sector in India has shown a significant growth in recent years, supported by several drivers such as the growing production of seeds, expanding seed portfolio and growing threat from weather. The industry is represented by major international and local players such as Incotec, Littles Oriental Balm and Pharmaceuticals Ltd, Centor India, Mahendra Overseas, Sampatti Industries and others.

Seed coating technology

seed coating taking place in a special machine

Coating seeds

There are multiple types of seed coating techniques involving different seed coating materials. These are the most common types in the seed coating process:

  • Pelleting; seeds get coated with inert materials to change their size and shape for improved plantability. The size and density of the seed is modified to enable precise metering during mechanical planting.

  • Priming; a consideration for seeds that are sensitive to high heat, seeds that require light for germination, and for growers who want more vigorous, uniform stands.

  • Encrusting; the technique of adding a small amount of material to a seed to enable accurate mechanical seed metering. Growers who are primarily concerned with reducing double or multiples rather than consistent seed spacing often choose to encrust their seeds.

  • Film coating;  the method of encapsulating a seed with a very thin layer of synthetic polymer or similar material. Film coating is ideal for seed species that do not require pelleting for precision planting.

Seed coating polymers

Polymers and polymer colorants dominated the seed coating materials market of India in financial year 2016. Polymer coating is an essential part of the seed industry in India.

In film coating, the chemicals are applied in a polymer that is sprayed on the seeds as they fall though a specialized seed coating machine. The polymer is rapidly dried, so that the seeds emerge with a complete, dry polymeric coating. This coating does not rub off the seeds, greatly reducing worker exposure and waste. In addition, colors can be added to the polymers to code different varieties or seed lots. Large-scale units capable of treating large quantities of seeds have been developed, making it feasible to treat high-volume agronomic crops by this method as well.

Some novel applications have also been developed using the film coating method. For example, artificial polymers have been developed that exhibit temperature-sensitive permeability to water. These polymers are permeable to water at warm temperatures, but not at cool temperatures. Seeds coated with these polymers will not imbibe water – that is, absorb water and swell – if the temperature is below the set point of the polymer, potentially protecting the seed from chilling injury or germinating in an unfavorable environment.

The coatings are also being used to delay germination after planting, such as for timing the emergence of parental lines at different times to ensure synchronous flowering for hybrid seed production. A starch-based biopolymer is also being used in film coating to slow water uptake and alleviate chilling injury.

Seed coating companies India

It’s possible to buy seed coating polymers from players like Incotec, Littles Oriental Balm and Pharmaceutical Ltd. However, smaller players like Mahendra Overseas and Sampatti Industries and Suboneyo Chemicals are also emerging in the market by supplying large quantities of materials to small/medium sized companies in the country.

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