SEED DRYING

Drying of seed lots, i.e., lowering down the seed moisture content to safe moisture limits, is very important in order to maintain seed viability and vigour, which may otherwise deteriorate fast due to mould growth, heating and increased micro-organism activity.  The other advantages of seed drying are:

1. Permits early harvest;
2. Permits long-term storage;
3. Permits more efficient use of land and man power;
4. Permits use of plant stalks as green fodder; and
5. Permits seeds men to sell a better quality product

Methods of Seed Drying

The drying of seeds is done by the following methods:

1. Sun drying
2. Forced air drying

Sun Drying:

In the absence of forced air drying facilities, the moisture content of seeds have to be reduced in the field before harvest, and later by sun drying on the threshing floor.  The system involves harvesting of crops when they are fully dried in the field, leaving the harvested produce in field for a couple of days to sun dry and later spreading the threshed and winnowed produce in thin layers on threshing floors to sun dry.  The main advantage of sun drying is that it requires no additional expenditure, or special requirement.  The disadvantages are delayed harvest, risks of weather damage and increased likelihood of mechanical admixtures.

If sun drying is to be done, the following precautions should be taken to insure seed quality:

1. Do not spread the produce on wet, dirty and Kacha threshing floors.
2. Only one crop variety, and produce from one plot, should be handled on a threshing floor, in order to maintain lot identity and to avoid mechanical admixtures

Forced air drying

In this system air (natural or heated) is forced into 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 of the air.  This is the most fundamental principle of forced air seed drying.