1. Title: Discuss plant breeding techniques used in self-
pollinated plants v/s those used in cross-pollinated
plants?
Name: Babooa Anusha

2. Plant breeding is the art and science of improving the genetic makeup of plants in relation to
their economic use for the mankind. Its continuous aim is to improve the quality, diversity and
performance of agricultural, horticultural crops. The objective of plant breeding is to develop
plant that is better adapted to human needs. Various approaches that are used for the genetic
improvement of crop plants are referred to as plant breeding techniques. The choice of breeding
techniques mainly depends on the mode of pollination, mode of reproduction, gene action and
breeding objective of crop species.
A plant breeder tends to divide crop plants species into two groups: self-pollinating plants and
cross pollinating plants.
In self-pollinating plants, the
pollen grains are transferred to
the stigma of the same flower or a
different flower in the same plant.
A self-pollinating plant is capable
of fertilizing itself and tends to be
highly homozygous because all of
its genes come from the same
parent. Example of self pollinated
plants is Rice, Wheat, Tomato,
Okra, Peanut, Potato, etc. Broadly,
there is two ways whereby self
pollination can occur.

3. However, if the pollen grains are
transferred to a flower in another
plant of the same kind, it is called
cross-pollination.
A cross-pollinated plant cannot
fertilize by itself and is likely to be
highly heterozygous. These
species include corn, rye, alfalfa,
clover as well as fruits, nuts and
vegetables.
Breeding methods for self-pollinating plants are different to some extent from those for cross-
pollinating ones. The main breeding methods that will be discussed in this report are as follows:
Commonly used methods known as Rarely used methods known as
general breeding method special breeding method
Plant Introduction Mutation breeding
Selection( pureline ;mass selection; progeny) polyploidy
Hybridization (pedigree; bulk,single seed Transgenic breeding
descent; backcross)
Heterosis
Recurrent selection, multiline varieties and synthetic varieties are mainly used for crop
improvement.
1. Plant introduction
It is introducing a plant into new regions from its growing locality. It is the easiest and
simplest method. Proper management and acclimatization is very important to prevent
losses. Quarantine has to play an important role in introduction to ensure that the
material which is to be introduced should not carry pest& diseases with it. It can be
used in both self and crossed pollinated plants.

4. Different geographical regions
Different soil type
2. Selection
A. Mass selection
It is the oldest & easiest method of selection and is useful in self-
pollinated species and rarely in cross-pollinated species. It is based
on the ability to recognize desirable or undesirable traits in plants of
a population. The varieties developed through mass selection are
more widely adopted than pure lines though they are not uniform. It
takes about 8 years to produce a variety by this method. Steps
involves: Eliminating undesirable plants as they are grown in the
field (negative mass selection); Tag desirable plants at maturity
(positive mass selection); Select best individuals and mix seed.
B. Pure line selection
It is a method in which a new variety is
developed by selection of a single best plant
progeny among traditional varieties or land
races. It is applied mostly to self-pollinated
crops. It is also used sometimes in cross-
pollinated species for development of inbred
lines. Steps involves: Selection of superior
individual plants (200-3000 plants); visual

5. C. Progeny selection
It is used extensively in cross-pollinated species. Plant are selected on basis of
phenotypic superiority and allowed to open-pollinate. Seeds are harvested
separately and progeny rows are grown from the selected plant. This process is
repeated till superior families are selected to produce a new variety.
3. Hybridization/ Heterosis
The mating of two lines of different genotype is known as hybridization. This method is
used in both cross & self-pollinated crops. However, it is common in cross-pollinated
and rare in self-pollinated species. Out crossing (crossing between genetically different
plant) in cross-pollinate crops often results in heterosis/hybrid vigour. Conversely, cross-
pollinated plants exhibit inbreeding depression, in the form of small size, poor vigour
which is contrary to self-pollinated species that do not exhibit inbreeding depression,
but may exhibit considerable heterosis.

6. Repeated inbreeding Repeated inbreeding
Inbred A Inbred B
F1 A B
A. Pedigree selection
It is a widely used method of A B
breeding self-pollinated species F1
(and even cross-pollinated
species such as crops produced
as hybrids). Detailed records of F2
the origin of the selected lines
are maintained. It produces new
cultivars faster than mass F3
selection. In self-pollinated crop,
it is used to release new
varieties. In cross-pollinated F4
crops, it is used to develop
inbred lines.
Fn

7. B. Bulk method
This method can handle
segregating generations, in
which F2 and subsequent
generations are harvested in
bulk to grow the next
generation. At the end of
bulking period, individual
plant selection and evaluation
is carried out in the similar
way as in pedigree method.
This method is used in self-
pollinated plant species.
C. Single seed descent
It is a method used in self-pollinated species. It is a modification of
the bulk method. Instead of bulking a whole seed lot of selected
plant, a single seed is selected randomly from each selected plant to
make bulk.

8. C. Backcross breeding Well-adapted cultivar
It conserves all good characteristics of a popular
adapted variety and incorporates a desirable
character from another variety. A cross between a
hybrid and one of its parents is known as backcross.
It is applicable to both self and cross-pollinated
Cultivar with too
species. This method is also used for development of
many wild
multilines and transfer of male sterility.
characteristics
New
4. Recurrent selection
It can be broadly defined as the selection of
desirable plants from a population followed by
recombination of the selected plants to form a
new variety. It is a refined version of the mass
selection procedure and is used mainly in
cross-pollinated species.
5. Synthetic and multi line varieties
Synthetic varieties are developed in cross-pollinated species. It is produces by crossing in
all combination a number of lines that combine well with each other. These varieties have
been of great value in the breeding for cross-pollinated crops whereby pollination control
is difficult. The maize program CIMMYT places a considerable emphasis on synthetic
varieties.
Multiline varieties are a mixture of several pure lines of similar phenotype (height, seed
color) but have different genes for the character under consideration. These varieties are
developed in self-pollinated crops.

9. 5. Mutation breeding
Inducing desirable mutations and exploiting them for crop
improvement is known as mutation breeding. It is more
valuable in self than cross-pollinated crops. It may occur
directly during cell division or by exposing the plant to
irradiation or chemical agents.
6. Polyploidy
Normal cell division
A cell is a polyploid if it has at least
twice the normal number of
chromosomes. It can occur spontaneously
or can be induced using chemicals such
as colchicines. The plants are larger Colchicines 2 diploid
diploid
compared to those having normal number dissolves cells
of chromosomes. However, it is rarely spindles
used in both self & cross-pollinated
tetraploid
crops.
7. Transgenic breeding
It serves to introduce gene sequences for
expression of a desired trait. It is applicable to
both types of crop species. This method is used
to solve specific problems which cannot be
solved by conventional breeding techniques.

10. Plant breeding has several useful applications in the improvement of crop plants. This has
increased the productivity and quality of the plant we grow for food, feed and fiber. However, it
has certain undesirable effects. Conventional plant breeding can no longer sustain the global
demand with the increasing population, decline in agricultural resources such as land and water.
Thus, new crop improvement technologies should be developed and utilized.
References:
Principles of plant breeding R.W.WALLARD. December 1960
Agricultural biotechnology, international service for the acquisition of
AGRI_BIOTECH application, Aug 2010.pdf
Breeding self-pollinated species.pdf
FIBL Dossier, plant breeding techniques, No2 September 2001, 1st
edition.pdf
EAMCET_QR_botany_SR_botany_11 crop improvement .PDF
Department of genetics and plant breeding, GBPR 211.pdf