Seed drying

• Is important to maintain seed viability and vigor which deteriorate fast due to mold growth, heating, and increased microorganisms.
• At the maturity stage, the moisture content of the seed is quite high (up to 45%) and is reduced to a safe level whether it has to be stored for a short or long period.
• For short-term storage (up to 9 months) the seed should be dried to a moisture content of 8-10%. For storage up to 3 years, it has to be dried to 6-8%.
• Drying air temperatures higher than 430C is injurious to seed quality.

Advantages of seed drying

– Permits early harvest.

– Permits long-term storage.

– Permits efficient use of land and manpower.

– Permits use of plant stalks as green fodder.

– Permits to sell a better-quality product.

Methods of seed drying

1. Sun drying:

• This method involves reducing the moisture level of crops before harvest, after harvest, and after the threshing of seeds on the threshing floor in a couple of days.
• Requires no additional expenditure; some diseases of seeds can also be controlled by the sun rays known as heliotherapy.
• Delayed harvests, risk of weather damage,e and increased likelihood of mechanical admixture.

2. Forced air drying:

• Natural or heated air is forced onto the seeds.
• The air passing through damp seeds picks up water. The evaporation cools the air and the seed.
• The heat necessary for evaporating the water comes from the temperature drop in the air.

Methods of forced air drying

a) Natural air drying: Natural air used.

b) Drying with supplemental heat: small quantities of heat to raise the temperature by about 10-200C to reduce RH.

c) Heated air drying: Air is heated considerably as much as 1100F.