Role and Goal of Seed Technology in Crop Production

Role of Seed Technology:

Feistritzer (1975) outlined the few roles of improved seed.

1. Seed – a carrier of new technologies.
2. Seed – a basic tool for secured food supply.
3. Seed – The principle means to secure crop yields in less favorable production areas.
4. Seed – a medium for rapid rehabilitation of agriculture in case of natural disaster.

1. A carrier of new technologies:

The introduced of quality seed of new verities and combined with other inputs significantly increased yield level e.g. in cereals, yield increased up to 112%, in potato –  24% & sugar beet - 142% in U. S. A. & central Europe.

In India the cultivation of high yielding verities have helped to increase food production from 52 million tones (1947) to nearly 200 million tones in 2000-2001

2. A basic tool for secured food supply:

The successful implementation of the high yield verities programme in India has led to a remarkable increase the production.

As a result, food imports from other countries have been substantially brought down in spite of the rapid population increase.

3. The principle means to secure crop yield in less favorable area of production:

The supply of good quality seed of improved verities, suitable to these areas is one of the crops. Immediate contribution that seed technology can make to secure higher crop yield

Goals of Seed Technology:

The measure role of seed technology is to increase agriculture production through the spread of good quality seed of high yielding verities.

1. Rapid Multiplication:

Increase in agricultural production through quickest spread of new verities developed (released) by the plant breeders.

2. Timely supply:

The improve seeds of new verities must be made available well in time, so that farmer is planned planting schedule (or showing time) without disturbed. They are able used good seed for planning (sowing) purpose

3. Assured high quality of seeds:

Is necessary to obtain the expected dividends from the use of sees of improved verities

4. Reasonable price:

The cost of high quality seed should be within reach of the average farmer. 

Methods of Breaking Seed Dormancy

Various methods have been used by seed scientist and technologists to break the dormancy of seed.

Simple and widely used methods are

A. Scarification:

Any treatment i.e. physical or chemical that weakness the seed coat, is known as scarification.

Scarification method is applied, when dormancy is imposed by hard seen coat e. g. in legumes- cajanus cajan, (tur), gram etc.

In this method there are various way to break hard seed coat such as:

1. Seeds are either rubbed on a sand paper manually. At the time of rubbing care should be taken that not to damage the axis of the seed e.g. Green gram & subabool.
2. When seed coat is too hard i.e. of woody nature, the seed coat has to be removing completely by breaking it. E.g. Rubber (Havea app) seed India teak wood seed.
3. Soaking treatment: Soaking hard seed coat in concentrated or diluted solution of sulphuric acid for 1 to 60 minutes, it remove seed coat impermeability. E. g. cotton seeds, India teak wood seeds etc.

B. Temperature Treatments:

1. When the dormancy is due to embryo factor i.e. the seed is incubating at low temp. (0- 5o C) over a substratum for 3 to 10 days placing it at optimum temp. Required for germination. E.g. mustard. – (Brassica campestrits)
2. Some seeds required a brief period of incubation (from a few hours to one to five days) at 40 to 50 oC before germinating at required temp. ( in this method care should be taken that moisture content of the seed is not more than 15% e.g. paddy (Oryza Sativa)
3. Hot water treatment is also an effective method of breaking hard- seed ness in legumes. In this method the seeds are soaked in water at 80oC temp. For 1 – 5 minutes (depending up on the type of seed) before putting for germination.

C. Light Treatments:

Same seeds do not germinate in dark thus it provides continuous or periodic exposure of light is essential e. g. Lettuce (Lactuca Sativa) required red light (660nm) or white light is essential for germination to occur.

D. Treatments with growth regulators & other Chemicals:

Endogenous dormancy may be due to presence of germination inhibitors. Application of low level of growth regulators (i.e. Gibberellins, Cytokinins and Ethylene etc) may break the seed dormancy.

Most widely used growth regulators are gibberellins and kinetics e.g. seeds of sorghum crop presoaking seed treatment with GA3 at the conc. Of 100 ppm have been used for breaking seed dormancy

Among other chemicals potassium nitrate (0.2%) and thio – urea (0.5 to 3%) are widely used for breaking seed dormancy in oat (Avena Sativa), barley (Hordeum vulgare), tomato (Lycopersicon spp).

(For prepare 100 ppm solution of GA3, weigh 100 mg of GA3 & dissolve in a few drops of alcohol and make up the final volume (1000 ml) by adding distilled water).

(50 ppm kinetin 5 mg dissolved in few drops of alkaline made with sodium hydroxide and makes the final volume 100ml it gives to final conc. Of 50 ppm)

Principles of Quality Seed Production

During seed production strict attention must be given to maintenance of genetic purity and other qualities of seed in order to exploit the full dividends sought to be obtained by introduction of new superior crop plant varities.

Genetic principles:

• Deterioration of varities:

 Genetic purity (trueness to type) of a variety can be deteriorating due to several factors during production cycles.

The important factor & real deterioration of varities listed by Kadam (1942) & these are

1. Developmental variations
2. Mechanical mixtures
3. Mutations
4. Nature crossing
5. Minor genetic variations
6. Selective influence of diseases
7. The technique of plant breeder

Mechanical mixtures, natural crossing and selective influences of diseases are most important reasons for genetic deterioration.

• Mechanical Mixture:

Mechanical mixture may take place at the time of sowing, it more than one variety is sown with same drill or through different varieties grown in adjacent field.

Two varities growing alongside each other the field are often mixed at the time of harvesting and threshing operation. Threshing equipments (i.e. threshing machine) is often contaminated with seeds of other varities.

The gunny bags, seed bines are also quite responsible mechanical mixture with seeds of other varities.

To avoid mechanical mixture, it must be necessary to rogue the seed fields and care should be taken at the time of harvesting, threshing and handling.

• Natural Crossing:

 In sexually propagated crops, natural crossing is most important source of vertical deterioration.

The deterioration in varieties due to natural crossing is of three reasons

1. Natural crossing with undesirable type
2. Natural crossing with diseases plants
3. Natural crossing with off- type of plants

According to Bateman (1947) genetic contamination is seed field due to natural crossing depends upon the some factors and these are

1. The breading system of species
2. Isolation distance
3. Vertical mass
4. Pollinating agents.

As the isolation between varieties is increased the contamination decreases. Isolation of seed crop is a primary factor in the seed production of crop plants of cross pollinated by wind or insects and their activities, humidity and temp. at the time of anthesis etc.

• Selective Influences of Diseases:

New crop varieties often become susceptible to new races of diseases often caused by parasite.

Some vegetative propagated stocks deteriorate fast it infected by viral, fungal and bacterial diseases. It is very important to produce diseases free-seeds /stocks.