An Exact Knowledge of History of Plant Breeding and Phases involved in it.

1. INTRODUCTION AND HISTORY
OF
PLANT BREEDING
By :-
E.Chethan Swamy
B.Sc.(Agriculture)

2. Introduction :
 Plant breeding deals precisely with the important aspects of
crop production i.e.. Yield, disease and insect resistance, quality
and tolerance to various stress conditions.
 It consists of the principles and the methods required for
favourably changing the genetic constitution of crop plants.
 This activity usually produces crop varieties better suited to
human needs in one or more aspects than the existing ones
 It can be also defined as “ Plant Evolution Directed by Man.”

3. History of Plant Breeding :
 Plant Breeding may be regarded to have progressed through
five distinct phases:
1. Domestication
2. Selection
3. Hybridisation
4. Novel Genetic Variation
5. Genetic Engineering

4. 1. Domestication :
 The first phase consists of Domestication during the prehistoric
humans brought wild plant species under the human
management.
 Thus domestication may be regarded as the most basic method
of plant breeding because all other breeding methods
applicable to a plant species only after it has been successfully
domesticated.
 Deliberate and Planned Introduction into an area of new plant
species or varieties from other part of plant breeding today.

5. 2. Selection :
 In the second phase conscious and planned Selection was
practiced to exploit the natural genetic variation existing in the
crop species. This resulted in number of improved varieties,
especially for self pollinated crops.
 The two basic schemes resulted form these namely Pureline
and Mass selection gave rise to many improved varieties of
different crops.
 However, once the natural genetic variability was exhausted,
these selection schemes were no longer attractive breeding
approaches, although mass selection is still used for purification
and maintenance of pureline varieties.

6. 3. Hybridization :
 The phase three Hybridization began to be exploited for the
crop improvement. The main feature is the planned and
controlled hybridization between diverse, selective
genotypes/varieties to create new or more desirable
combinations among the existing genes/ alleles.
 Based on the taxonomic relationship of the two parents the
hybridization may be classified into two groups :
1. Intervarietal hybridisation
2. Distant hybridization
 They has made an notable contributions particularly in
development of disease resistance varieties.

7. 4. Creating Novel Genetic Variation :
 The fourth phase of plant breeding began with an objective of
creating novel genetic variation not known/available in a crop
species.
 New alleles of existing genes were created by induced mutations
using x-rays, chemical mutagens like ethylmethane
sulphonate(EMS) etc…
 The Somaclonal variations achieves some extremely new and
useful alleles have been isolated from this approach
 The Polyploidy attempted to exploit the beneficial effects of
increased number of copies of a single genome or bringing
together two or more distinct genomes.

8. 5. Genetic Engineering :
 The next phase and current phase of Genetic Engineering,
which aims at the isolation and cloning of specific useful genes
of various organisms , and their transfer and expression into
plants.
 The DNA Recombinant technology revolutionised the
opportunities in crop improvement.
 Many achievements like flavoured tomato, and yielding valuable
and novel biochemical like insulin, interferon monoclonal
antibodies etc..

9. Thank You..