Seed

Concept of Seed

 Generally the leaving medium used for plant propagation is called seed. In order to get clear conception about seed it is necessary to know two definitions from two different points of view such as

A. According to Botanical Theory

 A seed is a fertilized and matured ovule such as– Rice, Wheat, Mustard, Mango, Jackfruit etc. Only the flowering plants can produce such types of seeds.

B. According to Agronomical Theory

 Any part of a plant, which can propagate, under favorable environment, plants of same variety is called seed. In this case branch, root, leaf bud etc. are used as seed, Pieces of sugarcane, potato, sweet potato, root of spined gourd, graft of mango, and erum of aroid are the examples of this type of seed.

Qualities of Seed

 Characteristics seeds mean the essential qualities is of seeds. The characteristics of good seeds are mentioned as under –

1. Purity of Seed

 Purity of seed means the quantity of pure seed in a particular sample of seeds. If seeds are preserved in controlled condition the seeds retain their viability for the definite period. If seeds contain seeds of other verities, weed seeds and stones, their qualities are lost. During seed production, care should be taken. So that the seeds are not mixed with seeds of other verities of the same crop, dirty material or weed seeds.

2. Varietal Purity of Seeds 

 Purity of seed is lost when the seed sample contain other materials in mixed condition. Purity of seed is maintained when production and processing are done under controlled condition.

3. Germination Capacity of Seed

 The quality of seed is measured by determining the percentage of germination of seeds in a particular sample. When germination percentage of a particular sample of seed is 70-80% then the seeds are considered to be good.

4. Vigour of Seeds

 When the seeds of the sample are active, living and healthy and can grow rapidly even under adverse condition, then those seeds are called as seeds of high vigour.

5. Shape and Size of Seeds

 Good seed will always be matured healthy and of normal size

b. Moisture content of the Seed

 The initial percent of moisture contained in the seed is the seed moisture

7. Freeness from Diseases

 Seed should be free from disease and pest

Classes of Seeds

 According to Bangladesh seed rule 1980 seeds can the divided into 3 classes such as
 1. Breeder Seeds
 2. Foundation Seeds
 3. Certified Seeds.

Breeder Seeds

 The seeds production under the supervision of plant breeders maintaining all genetically qualities is called breeder seeds. Breeder seed is the first step of approved seed production process.

Foundation Seeds

 Foundation seeds are produced from breeder seeds. The seeds produced in controlled condition under seed certification agency, maintaining seed production rules and purity of seeds are called foundation seeds.

Certified Seeds

 Certified seeds are produced from foundation seeds. The seeds produced by the enlisted farmers of seed certification agency certify these seeds after proper examination and verification. The seeds are then supplied to the farmers for their use.

Seed Production Technology

 Seed production is complex process. In order to get improved types of seeds, seeds are to be produced by following proper techniques and methods, the similar steps should be following in case of seed production as done in case of crop production. The difference is that the seeds are produced by the enlisted farmers of seed certification agency under controlled condition.

Steps of Seed Production

 The following steps are followed in case of seed production such as-
 1. Selection of field for seed production
 2. Separation of seed, field
 3. Collection of seed
 4. Determination of seed rate
 5. Preparation of selected land
 6. Sowing of seeds
 7. Rouging
 8. Inter-cultural operation

Selection of Field for Seed Production

 Fertile land should be selected for seed production. The land must be weed free and be well aerated. If would be better if some variety of seed had not been cultivated in the selected land in the previous year. The selected land should have at least 2% organic matter.

2. Sparation of Seed Field

 There should be a gap of definite distance between the land selected for seed production and the nearby field of same crop. The objective of this is to avoid any admixture of the desired crop seed with other varieties

3. Collection of Seed

 Seed collection is an important step of seed production. Certified seeds must be collected for seed production. The following information should be known before seed collection.
 a. Name of the variety
 b. Name the number of the seed producer
 c. Percentage of seed of other variety
 d. Germination percentage of seed
 e. Moisture content of seed
 f. Date of verification and testing of seeds The above mentioned informations are written in a guarantee paper are tagged with the seed bag or packet

4. Determination of Seed Rate

 Seed rate per hectare is fixed considering purity, germination percentage and size of seeds, sowing time, fertility of soils etc.

5. Preparation of Selected Land

 Land preparation for a particular variety of seeds is of a particular type. For example in case of producing seeds of transplanted Aman paddy land has to be prepared by pudding. Again in case of wheat the land is to be prepared by 4-5 ploughing in dry condition and should have to be well pulverized. The fertilizer, doses also vary from seed to seed.

6. Sowing of Seeds

 The selected crop seeds should be timely sown in lines. Every seed should be sown in seed bed in same depth. The depth of sowing of a particular seed depends or the size, moisture content and texture of soil.

7. Rouging

 Inspite of using pure seeds for sowing some plants of other varieties and weeds  may be seen in the field. So the seed field should have to be visited frequently and the undesired plants are to be uprooted. Rouging is done in three steps, such as –
a. Before flowering
b. During flowering
c.  During maturity

8. Intercultural Operation

 Seed production requires sufficient intercultural operation. A list of intercultural operation is given here under
 a. Application of fertilizer in balanced dose.
 b. Application of organic manure.
 c. Irrigating the land as and when required.
 d. Draining excess irrigation and rain water of accumulates.
 e. Weeding
 f. Controlling diseases and pests.
 g. Top dressing of fertilizer

9. Collection of Seeds

 Seeds are to be harvested soon after they show the colour of ripening or maturation. Then these are to be threshed and cleaned by winnowing.

Seed Processing

 The desired seed may be mixed with the weeds and other crops seeds. After threshing and winnowing the seeds have to be graded. The graded seed should have to be sundried for few days and then have to be preserved.

Seed Preservation

 Seed moisture is the main factor of keeping the seed alive. The more misture content in the seed is the more quickly it will lose its viability. If the seeds of cereals like rice. wheat etc. contain moisture content higher than the seeds are spoiled due to attack of diseases and insects. Again if the moisture content is less than a prescribed limit, viability may also be lost.

General Principles of Seed Preservation 

1. The seed godown should be in dry and cool place.
2. Seeds have to be sundried well and cooled in shade.
3. The godown should be well aerated
4. Seeds are to be preserved in any pot or polythene bag under airtight condition.
5. The seeds are to be brought out frequently from the seed godown for sun drying.
6. In order to avoid invasion by the insect pests the godown is to be fumigated.