INTRODUCTION:

 

Man is almost absolutely dependent on plants for his food.

The things he eats, virtually without exception, are

- plant materials such as foodgrains, pulses, vegetables, etc.

- derived from plants for eg., meat, eggs and dairy products.

Plants are also the major source, directly or indirectly, of most the clothing, fuel, drugs and construction materials.

 Considering the prime importance of plants, men have long been concerned with developing types of plants better suited to satisfy their needs.

 Plant breeding as a technology has helped in bringing about green revolution in India to fulfill the national requirement of food production.

The advance plant breeding methods involve the use of genetics, molecular biology and tissue culture techniques for developing plants with desired traits.

 

4.1 PLANT BREEDING:

 Plant breeding is an applied branch of Botany which involves collective use of an art and science for changing and improving the heredity of plants in order to create desired types.

It involves the purposeful manipulation of plant species for developing desired plant types

- better suited for cultivation,

- give better yield

- disease resistant

- improvement in the quality

- tolerance limits to environmental stresses (like salinity, drought and extreme temperatures)

- resistance to pathogens and pests.

The development of specific characters of agronomic importance in different crops

1. dwarfness,

2. intensive branching,

3. reduction in dormancy period

 Conventional plant breeding has been practiced for thousands of years, since the beginning of human civilization.

The recorded evidence of plant breeding dates back to about 10,000 years ago.

Many present day crops are the result of domestication in ancient times.

Domestication is the process of bringing a species under human management and all our major food crops represent domesticated varieties.

In classical plant breeding,

- crossing or hybridization of selected pure-lines is done

- artificial selection is made for the plants with desirable traits.

 Various private commercial companies and government institutions carry out plant breeding programmes.

 In the systematic approach of producing a new genetic variety of a crop.

 The five steps in plant breeding are:-

1. Collection of Variability

2. Evaluation and selection of parents

3. Cross hybridisation among the selected parents

4. Selection and selfing of superior recombinants

5. Testing, release and commercialization of new cultivars