This document discusses seed drying methods and factors that affect the drying process. It describes drying as the evaporation of moisture from seed surfaces through movement to the surface from within. The drying temperature depends on the initial seed moisture content, with lower temperatures used for higher moisture contents. Methods mentioned include solar drying, shade drying, forced air drying, vacuum drying, and batch or continuous flow drying using heated air. Factors noted as influencing drying include the initial moisture content, humidity, temperature, air flow, seed properties, and drying system design.

1. SEED DRYING

2. DRYING
Drying is the process of evaporation of moisture from seed
surface.
It is the movement of moisture to surface from or within the
seed.
Seed drying is carried out various types of driers based on
the requirement.

3. Hence drying temperature is decided as below
Greater the seed moisture content lesser should be the
drying temperature and vice versa.
10% MC and below 1100 F (43.30 C)
10-18 % MC 1000 F (42.20 C)
18-30 % MC 900 F (32.20 F)

4. Drying methods
Solar or sun drying
Natural shade drying
Forced air drying
Vacuum drying or dehumidified drying
Hot air drying
Batch / Bin drying
Continuous flow drying
Multi-pass drying and tempering

5. Forced natural air drying:
Generally ordinary seed godowns are provided with two types of ventilators
for free movement of air circulation.
In modern godowns, provisions are to be made for forcible circulation of air
with the help of an electronic blower.
The outside air which is comparatively dry is circulated in the godown and
thereby the seed get dried up in this process.
This is possible only in dry months.

6. Forced heated air drying:
In this method, the outside air is heated with the help of burner heater and
circulated into the godown for drying.
This principle is employed in several types of the modern dryers.

7. Mechanical drying or artificial drying:
This involves the use of heated or unheated air or others which are
forced through a drier holding the seeds.
Mechanical drying:
Quick drying
Large quantity drying
Equipment used : Dryers

8. DIFFERENT TYPES OF DRIERS
a) Batch bin dryers (or) Metal bin dryers
i) Rectangular metal bin dryers
ii) Circular metal bin dryers
b) Continuous flow dryers
i) L.S.U. dryers (Louisiana State University)
ii) Non mixing column dryers

10. Batch Bin dryer

11. Continuous flow dryer

12. Column Batch-Dryer

13. Factors affecting seed drying
Initial seed moisture content
Relative humidity of the air
Temperature
Air flow rate
Seed size
Seed depth
Permeability of seed to moisture migration
Amount of trash in the seed lot
Design of drying system

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