Seed in Agriculture -
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In this article -
- Definition of Seed
- Formation of Seed
- Structure of seed embryo
- Quality of seed
- Conditions for a good quality seed
- Types of seed
- Seed Tag
- Isolation distance
Definition of Seed -
Any part of the plant that has capability to produce the new plant is called seed.
In other words - Seed is the any part of plant that have the re-germination capacity.
Formation of Seed -
The seed is formed by the fusion of male gamet and female gamet of plants. The fusion of male and female gamet is called fertilization.
The pollination is a important stage for fertilization. Pollination can be of two types -
- Self Pollination
- Cross pollination
The arrival of pollen grain on stigma is called pollination. Pollen grain is male gamet and ovary is female gamet of plants. Then pollen grains travel to ovary from stigma. The process of fertilization occurs in ovary. Due to pollination two male gamets enters to the ovary. In ovary there are three female gamets.
A male gamet fuses with a female gamet and forms zygote.And the other male gamet and two female gamets form the endosperm this endosperm gives nutrition to the embryo. The zygote forms embryo after maturing. Embryo after maturing forms the fruits. After fertilization the fruit formation is done in ovary. Mature ovary is called fruit and the ovule in the ovary forms the seed. The seed is protected by the fruit.
Structure of seed -
The seed is formed from ovule. There is a tiny hole in the top part of seed that is called micropyle. It allows the water to enter in the seed. The micropyle helps in germination of the seed. The outer part of seed is called testa and inner part of seed is called tegmen.
Structure of Embryo -
Embryo consists of these structures-
1. Cotyledon - It is an embryonic leaf. Cotyledon provides the nutrition to plant embryo and helps the embryo to become a photosynthetic plant . In dicot seeds the two real cotyledon can be seen. In monocot seeds the real cotyledon is not available, it turns to endosperm.
2.Radicle - It is the part of plant embryo that turns in primary root. The radicle is the first part that emerges from the seed during the process of germination. The structure of radicle is same in both monocot and dicot seed.It is geotropic in nature. It grows downward in the soil
3.Plumule - It is the part of plant embryo that turns in the stem. It is phototropic in nature. It grows upward the soil. It emerges from the embryo and develops as stem of the plant.
4. Epicotyl - It is situated just down of plumule. It helps the plant stem to grow out.
5. Hypocotyl - It is situated right above of the radicle. It is the part of embryonal axis that helps stem to grow out.
6. Testa and tegmen - The outer part of ovule is called testa. And the inner part of ovule is called tegmen.
Quality of seed -
The quality of seed is a important factor in agriculture. And in India it becomes more important. The agriculture is the backbone of India. But in India only the 12 percent farmers are getting good quality seeds.
Characteristics of good quality seeds -
The main characteristics of good good quality seed -
1. Productivity - A good quality should have capable to produce at least 10 - 15 percent more amount in comparision of local seed.
2. Genetic Purity - A good quality seed should have at least 98 percent genetic purity that is genetic impurity should not more than 2 percent.
3. Physical Purity - It should have at least 98 percent physical purity that means physical impurity should not more than 2 percent.
4. Percentage of moisture - It should be between 6 - 14 percent for good production. Moisture percentage in -
- Spice - 6 to 8 percent
- Cereal crops - 10 to 12 percent
- 5Oilseed - 6 to 8 percent
- Legume - 8 to 12 percent
Calculation of moisture percentage - formulae of moisture percentage
m1 - m2
Moisture percentage =--------------- * 100 m2
m1 = Weight of seed sample
m2 = weight of seed sample after drying
5. Physical Purity - It should be more than 98 percent.
weight of pure seed after remove impurity
Physical impurity = ___________________________________* 100
weight of seed sample
Physical Purity of -
- Ladyfinger - 99 percent
- Carrot - 95 percent
- Jute - 97 percent
- Groundnut - 96 percent
- Sorghum - 98 percent
- Millet - 97 percent
- Rice - 96 percent
- Barley - 98 percent
- Wheat - 98 percent
- Onion - 98 percent
- Chillies - 98 percent
- Soyabean - 98 percent
- Linseed - 98 percent
- Tomato - 98 percent
6. Germination percentage - It should be more than 60 percent. The transition of seed from a dormant state to an active state is called germination. The germination of seed doesn't decide that seed is alive or not alive. If the seed doesn't germinate it could be in dormancy.
Germinated seed
Germination percentage = ----------------------------- * 100
total seed
Germination percentage for -
- Sorghum - 80 percent
- Millet - 75 percent
- Rice - 80 percent
- Wheat - 85 percent
- Arhar - 75 percent
- Moong - 75 percent
- Pea - 75 percent
- Tomato - 70 percent
Method for seed germination test -
- Petri dish method
- Towl method
- Saod Method
- Peg dol method
- Paper towl method
7. Real value for seed -
The real value of seed is the product of germination percentage and Physical purity percentage. It is donated in percentage. It should be at least 75 percent for good production .
8 . Other variety seed -
The amount of other variety should not more than 0.1 percentage for a good quality seed.
9. Weed -
The amount of weed should not more than 0.2 - 0.5 percent for a good quality seed .
Seed viability - Seed viability is a measure to find the alive seeds in a lot of seed that can produce the plant.
The main method for the determination of the seed viability is tetrazolium method.
In this method the seed is stained in 2,3,5 - tetrazolium chloride. If the seed gets stained it means that seed is alive. George Lakon discoverd this method for seed viability measuring.
Types of seed - It can be classified in for types -
- Nucleus seed
- Breeder Seed
- Foundation seed
- Certified Seed
1. Nucleus seed - It is produced by original breeder, institute , state agriculture. Nucleus seed is 100 percent genetically pure and 100 percent physical pure seed . Nucleus seed has no tag.
2. Breeder Seed - Breeder seed is produced from the nucleus seed in supervision of original breeder, instituite. Genetic purity and Physical purity is maintained to 100 percent in breeder seed. The tag colour of breeder seed is yellow.
3. Foundation Seed - It is produced from breeder seed. This seed is produced in farmer's field. In foundation seed the genetically purity and physical purity is maintained to 98 percent . The tag colour of foundation seed is white.
4. Certified Seed - It is produced from foundation seed . The seed recieved for the farming by the farmer is certified seed. Genetically purity and physical purity is maintained to 100 percent in certified seed, the tag colour of certified seed is blue.
Seed Tag -
1. Breeder seed -
- Dimension - 12 * 6 cm
- Yellow Tag
2. Foundation seed -
- Dimension - 15 * 7.5 cm
- White tag
3. Registered Seed -
- Dimension - 15 * 7.5 cm
- Purple tag
- This seed tag is not used in India.
4. Certified seed tag -
- Dimension - 15 * 7.5 cm
- Blue tag
Isolation Distance -
Isolation is the minimum sepration distance between two or more varities of same crop for purpose of keeping seed pure. Isolation distance is kept between two varities of same crop species.
Isolation distance is kept more in cross pollination species. And Isolation distance is less in self pollination species.
Isolation distance -
Crop Isolation distance Isolation distance
Foundation seed Certified Seed
______________________________________________________________
1. Rice 3 cm 3 cm
________________________________________ ______________________________________
2. Wheat 3 cm 3 cm
_______________________________________ ______________________________________
3. Tomato 50 cm 25 cm
____________________________________________ _________________________________
4. Groundnut 3 cm 3 cm
__________________________________________ _________________________________
5. Soyabean 3 cm 3 cm
_________________________________________________ ___________________________________
6. Pea 20 cm 10 cm
___________________________________________________ _______________________________
7. Oilseed 100 cm 50 cm
____________________________________________________ _______________________________
8. Jowar 300 cm 200 cm
____________________________________________________ ____________________________
9. Bajra 1000 cm 200 cm
___________________________________________________ _________________________________
10. Cotton 50 cm 30 cm
___________________________________________________ _________________________________
11. Rapseed, Mustard 400 cm 200 cm
_____________________________________________________ ________________________________
12. Carrot 800 cm 800 cm
_______________________________________________________ ______________________________
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