Seed technology:
6.1 Definition of seed , seed technology
6.2 Difference between seed and grain
6.3 Importance and scope of seed and Seed technology
6.4 Seed quality and its determinants
6.5 Types of seeds
6.6 Classification of seed in Nepal(Nucleus, Breeder, foundation, certified, improve)
UNIT-6
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DEFINATION OF SEED:
-The fertilized, matured ovule consisting of an embryonic plant together with a store of food, all surrounded by a protective coat.
-A seed is the small, hard part of a plant from which a new plant grows.
DEFINITION OF SEED TECHNOLOGY
seed technology define as “that discipline of study having to do with seed
production, maintenance, quality and preservation”.
Seed technology define as "the methods through which the genetic and physical characteristics of seeds could be improved. It involves such activities as variety development, evaluation and release, seed production, processing, storage and certification."
Differences between seed and the grain.
They contain high protein, starch and oil reserves that help in the early stages of growth and development in a plant.
These reserves are what make many cereals and legumes major food sources for a large proportion of the world's inhabitants.
Seeds protect and sustain life.
They are highly organized fortresses, well
stocked with special supplies of food
against long siege.
Seeds are vehicles for the spread of
new life from place to place by the ele-
ments and by animals and people.
Seeds are food for man and animals
and other living things.
Seeds are wealth.
Important scope of seed technology:
1. Helps in Rapid multiplication: which Increase in agricultural production through quickest possible spread of new varieties developed by the plant breeders.
The time taken to make available the desired quantities of seeds of improved varieties to farmers should be considered as a measure of efficiency and adequacy in the development of seed technology in the country.
2. Timely supply: The improved seeds of new varieties must be made available well in time, so that the planting schedule of farmer is not disturbed and they are able to use good seed for planting purposes.
3. Assured high quality of seeds: This is necessary to obtain the expected
dividends from the use of seeds of improved varieties.
4. Reasonable price: The cost of high quality seed should be with in reach of the average farmer.
Seed Quality
Thompson (1979) defined seed quality as a multiple concept comprising several components and their relative importance in different circumstances and laid much emphasis on
1.Physical purity
2. Species purity / Genetic purity
3. Freedom from weeds
4. Germination percentage
5. Seed vigour and health
6. Seed Moisture content
7. Seed size, weight and specific gravity
Seed quality characters: A good seed should have the following quality characters.
(यो सायद यत्रो लेख्नु नपर्ला हैं। कैलाश गुरु लाई सोध्नु हैं)
1. Improved variety: It should be superior to the existing variety i.e. the yield should be higher by 20-25% than the existing variety or it should have some desirable attributes like disease resistance, drought resistance, salt tolerance etc., with good yield potential.
2. Genetic Purity: The seed should be true to type. The seed should possess all the genetic qualities / characters, which the breeder has placed in the variety, genetic purity has direct effect on the yields. If there is nay deterioration, there would be proportionate decrease in the yield or performance.
3. Physical Purity: Physical purity of a seed lot refers to the physical composition of the
seed lots. A seed lot is composed of pure seed, inert mater, broken seeds, undersized seeds, soil and dust particles weed seeds, OCS etc.Higher the content of pure seed better would be the seed quality. Pure seed together with germination gives the planting value of the seed lot.
4. Seed germination and vigour: Seed germination refers to the ability of a seed when planted under normal sowing conditions to give rise to a normal seedling. Seed vigour refers to the sum total of all seed attributes that give effective plant stand in the field.
Higher germination percentage and vigour gives adequate plant population and uniform growth, which have profound effect on, yield and determine the planting value of the seed.
5. Freedom from weeds and other crop seeds: This is an extension of physical purity described earlier. There are certain weed species, which are very harmful to the crop and once established they are difficult to eradicate. An absolute freedom from seed of such species is highly desirable and is one of the important criteria for determining the planning
quality of seeds.
6. Seed health: Seed health refers to the presence or absence of disease organisms or insect pests on the seed. The quality of a seed lot depends on its health, hence the seed should be
free from seed borne disease and insect pests.
7. Seed moisture: The seed moisture is the most important factor in determining the seed germination and viability during storage. At high seed moisture content there is high incidence of pest attack and at moisture content above 16% seed get heated and the viability is lost. Hence the seed should be stored at safe moisture levels of 11-13%.
8. Seed size, weight and specific gravity: Seed size, weight and specific gravity has been found to have positive correlation with seed germination and vigour in many crops. Therefore the seed should be bold with high specific gravity.
9. Seed Colour: The colour of the seed often reflects the condition during seed maturation. The farmers from ancient times have regarded good normal shine as invariable quality guides. The colour and shine deteriorates only when the weather conditions are adverse during maturation or when insects infest the crop or when it is handled badly. The seed lots having high genetic purity, high germination and with a minimum amount of inert matter, weed seeds and other crop seeds and are free from diseases is said to be of high quality and if it is lacking of these it is said to be of low quality..
Classes of Seeds
1. Nuclear seed : This is the hundred percent genetically pure seed with physical purity and produced by the original breeder/Institute /Agriculture University (AU) from basic nucleus seed stock. A pedigree certificate is issued by the producing breeder.
2. Breeder seed
Breeder seed is the vegetative propagating material which is directly controlled by the plant breeder for breeding programme. It is genetically and physically pure seed. It is supervised by the qualified plant breeders so as to protect it from any contamination. This type of seed is produced in very limited amount and other seeds are the progeny of this breeder seed. Breeder seed is labelled by the golden yellow color certificate.
3. Foundation seed
Foundation seed is the progeny of breeder seed. It is produced under the supervision of certification agency and also certified by it. It is also physically and genetically pure seed like breeder seed. It is produced in very limited amount but little bit more than breeder seed. Foundation seed is labelled by the white color certificate. Foundation seed is then distributed to the registered growers.
4.Certified seed
Certified seed is the progeny of foundation seed. It is produced by the registered seed grower under supervision of seed certification agency. Certified seed is the seed which is produced for the distribution of seed to the farmer for the commercial cultivation. So, it is produced in large amount. This type of seed is labelled by the blue color certificate. There are two sub categories in certified seed:
a) Certified seed (I)
b) Certified seed (II)
Importance of seed certification
1. Maintains high quality of different kinds and varieties of seeds among the farmers through certification.
2. Ensures the acceptable standard of seed viability, vigor, purity and germination percentage.
3. Achieves objective of plantation.
4. Better yield, drought tolerance, herbicides tolerance, pest tolerance and other improved traits.
5. Helps knowing the quality of mother plant.
5. Improve seed: