Seed Production / Seed Selection Techniques

SEED PRODUCTION TECHNIQUES AT FARMER LEVEL

Objectives of the topic:

1. What is a good seed?
2. Why should we use good seed?
3. Why we should produce our seed? Can we produce our seed?
4. What are the characters of a good seed?
5. Methods to protect genetic purity?
6. Techniques of good seed production?
7. Why farmers can’t use their seed and at what situations?
8. Differences between straight variety and hybrid?

What is a good seed?

Seeds which have genetic purity and physical purity

1. Genetic purity:

The seed should produce same variety of crop from where it was collected. New plant should resemble the parent plant in all aspects. Hybrid seeds never resemble their parents. Genetic purity in hybrids means presence of similar characters in progeny. Different crops have different parameters of genetic purity.

Advantages of having genetic purity:
1. Will give good crop yield/productivity
2. All seeds are similar and posses same quality
3. Seeds will provide standard yields
4. Never loses unique nature

Physical purity:
Physical purity refers to seeds free from mixing of other crop seeds, disease free seeds and free from inert materials. To produce good quality seeds we should use good source seed. Farmers can produce good source seeds in their fields with few precautionary measures. These seeds can get from agricultural research stations.

Seed certification:
Seeds released by agricultural research institutions are known as notified varieties. Any
government/private organization can release their varieties after testing by these institutes. This type of seeds can get certification through seed certification agency. But all this process is not necessary according to regulations. This can be done on voluntary basis only.

Techniques to conserve genetic purity:
1. Using good source seed 2.Maintaining isolation distance 3.Rouging

1. Using good quality source seed:
Good quality source seed refers to those seeds collected from their fields or breeder
seeds/foundation seeds released by research institutes.

1. Source seeds:
A. Breeder seed: Those seeds which have 98% genetic purity
B. Foundation seed: Those seeds which kept for seed production from breeder seeds or seeds produced by seed production companies

2. Certified seeds: Those seeds certified by certification agency after visiting seed production plots and examining the quality parameters.

3. Truthful seeds: If farmers or companies sold their seeds by showing quality parameter through their label without certification, those seeds are known as truthful seeds. Government introduced this system in 1960. These seeds don’t need permissions from government, but seed law will regulate the quality parameters mentioned in the label. Complaints against these seeds can be filed on consumer forum.

2. Mantaining Isolation distance:
Pollen from one plant (male parts in flower), crossing with stigma (female parts of flower) is known as cross pollination. Cross pollination will generally happen between the adjacent plants. If different varieties of same crop are located adjacent to each other will lead to cross pollination. Cross pollination between different varieties will deteriorate genetic purity. Isolation distance is needed to avoid cross pollination.

Isolation distance means:
The distance required to maintain genetic purity is known as isolation distance. This distance will vary with crop. Isolation distance is more in case of cross pollinated crops such as Redgram and it is less in case of self pollinated crops.

3. Rouging:
Plant varieties other than the variety grown for seed production are known as offtype. Removal of offtypes is one of the important activities in seed production. Genetic purity will disturbed through cross pollination between offtypes and the variety. Offtypes should be removed before they reach flowering stage.

Isolation distances for different crops:
For self pollinated crops (in meters):

For cross pollinated crops (in meters):

Isolation distance depends on arrangement of flower, plant height, and number of pollen and weight of pollen.

Ex: As the number and weight of pollen is less in Castor, isolation distance is very high in Castor.

Rouging time for different crops:

Techniques to conserve Physical purity:

A. Crop harvesting – Seed collection – Threshing
B. Crop rotation
C drying
D. Seed storage

A. Crop harvesting – Seed collection – Threshing:
Harvesting parameters will change with crops. Harvesting of crop at appropriate time is crucial for producing good seed. Select those plants with good health and grains. Harvest those plants separately and keep them aside for seed collection. Care should be taken while threshing to avoid mixing of offtypes. Threshing can be done on a cement floor or clean land.

B. Crop rotation:
Crop rotation in seed production plots will reduce the problem of offtypes and pests and diseases.

C. Drying:
Grains should be dried under sunlight (between 9-11AM for 5-6days) to remove moisture in the seeds. Grains should be dried slowly and uniformally. Excessive drying will reduce germination ability. Low amounts of drying will allow growth of fungus and ultimately quality of seed will affect. Farmers believe that seed drying during amavasya will reduce pest incidence.

D. Seed storage:
Selection of appropriate storage device is critical for storing seed for long time. By regulating temperature and moisture we can conserve seed germination ability. Generally temperature of 300C and 70% humidity in air we can store seeds for 2-5 years. These parameters will change with crops.

Suggestions for production of good quality seeds:

1. Maintain isolation distance
2. Rouging of offtypes
3. Take up seed production in those areas where climate is suitable for the crop
4. Practice crop rotation
5. Leave few rows around bunds and collect seed from middle rows
6. If you allow one offtype plant, it will give 500 offtype plants in next crop
7. Proper care is needed to prevent mixing of offtypes during threshing