Hybridization

Hybrid/Hybridization
• Hybrid: Individual produced as a result of cross between
two genetically different parents is known as hybrid.
• Hybridization: The production of a hybrid by crossing two
individuals of unlike genetical constitution is known as
hybridization. Or the mating or crossing of two plants or
lines of dissimilar genotype is known as hybridization.
• Hybridization is an important method of combining
characters of different plants.
• Hybridization does not change genetic contents of
organisms but it produces new combination of genes.

Hybrid plants
• Hybrid Lilies
• Sweet Corn
• Meyer Lemon Trees
• Hybrid Maize
• Better Boy Tomatoes
• Rabbage
• coconut

History
• The first natural hybridization was recorded by
Cotton Mather (1716) in corn. The first artificial inter-
specific plant hybrid was produced by Thomas Fairchild
in 1717. It is commonly known as ‘Fairchild Mule’.
• Hybridization was first of all practically utilized in crop
improvement by German botanist Joseph Koerauter
in 1760.
• Mendel onward, the hybridization had become the key
method of crop improvement.
• Today, it is the most common method of crop
improvement, and the vast majority of crop varieties
have resulted from hybridization.

Objectives
1. To artificially create a variable
population for the selection of types
with desired combination of characters.
2. To combine the desired characters into
a single individual, and
3. To exploit and utilize the hybrid
varieties.

Types of Hybridization:
(i) Inter-varietal hybridization:
• The crosses are made between the plants of the
same species.
• It is also called intra-species hybridization
• Commonly used method
• Example: Crossing of two varieties of wheat,
rice, carrot, etc.
• It is further classified into two
A) Intra-specific
B) Inter-specific

(ii) Distant hybridization/Intra-varietal
hybridization:
• The crosses are made between the plants of
the same varieties.

Procedure OR methods of
Hybridization:
It involves the following steps:
(i) Selection of parents.
(ii) Selfing of parents or artificial self-
pollination.
(iii) Emasculation.
(iv) Bagging
(v) Tagging
(vi) Crossing
(vii) Harvesting and storing the F1 seeds
(viii) Raising the F1 generation.

Selection of parents.
• The selection of parents depends upon the aims and
objectives of breeding.
• Parental plants must be selected from the local areas
and are supposed to be the best suited to the existing
conditions.
• There are various methods by which plant selection
is carried out, namely selection for uniform plants,
known as pure line selection(selection of single best
plant progeny among traditional varieties);
selection from field-grown plants, known as bulk
selection or mass selection; and selection from a
well-documented list of parentage, commonly known
as the pedigree system.

Selfing of parents or artificial self-
pollination.
• It is essential for inducing homozygosity (state
of possessing two identical forms of a
particular gene) for eliminating the undesirable
characters and obtaining inbreeds.
• There are two types of self-pollination:
in autogamy, pollen is transferred to the stigma
of the same flower;
• In Geitonogamy, pollen is transferred from
the anther of one flower to the stigma of
another flower on the same flowering plant.

Emasculation
• It is the third step in hybridization. Inbreeds are
grown under normal conditions and are
emasculated.
• Emasculation is the removal of stamens from
female parent before they burst and shed their
pollens.
• It can be defined as the removal of stamens or
anthers or the killing of the pollen grains of a
flower without affecting in any way the female
reproductive organs.
• Emasculation is not required in unisexual plants
but it is essential in bisexual or self-pollinated
plants.

unisexual plants
• Date palms flower
• Sagittaria flower
• Corn flower
• Papaya flower
• Cucumber flower
• Rye
• Carrot
• Sweetpotato

Bisexual or self-pollinated plants.
• Habiscus plant
• Mustard plant

Various methods used for
emasculation are:
•Assignments

Bagging
• The emasculated flower or inflorescence is immediately
bagged to avoid pollination by any foreign pollen.
• The bags may be made of paper, polyethene paper, butter
paper, glassine or fine cloth.
• Butter paper or vegetable parchment bags are most
commonly used.

Tagging:
• The emasculated flowers are tagged just after bagging.
Generally circular tags of about 3 cm or rectangular tags of
about 3 x 2 cm are used. The tags are attached to the base
of flower or inflorescence with the help of thread.
• The information on tag must be as brief as possible but
complete bearing the following information:
(i) Number referring to the field record
(ii) Date of emasculation
(iii) Date of crossing
(iv) Name of the female parent is written first followed by
a cross sign (x) and then the male parent,
E.g., C x D denotes that C is the female parent and D is the
male parent.

Crossing:
• It can be defined as the artificial cross-pollination
between the genetically unlike plants. In this
method mature, fertile and viable pollens from the
male parent are placed on the receptive stigma of
emasculated flowers to bring about fertilization.
• Pollen grains are collected in petridishs (e.g., Wheat,
cotton etc.) or in paper bags {e.g., maize) and
applied to the receptive stigmas with the help of a
camel hair brush, piece of paper, tooth pick or
forceps. In some crops (e.g., Jowar, Bajra) the
inflorescences of both the parents are enclosed in
the same bag.

Significance of Hybridization
• New plants with variations in genetic characters
are produced
• It incorporates many desirable characters of
other plants(like high yield, resistant to pests, etc)
into a single variety of plant
• It produces hybrids which are better adapted to
changes in the environment
• Hybridization is also development by asexual
hybridization or protoplast fusion in tissue culture
media.

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Hybridization

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