Presentation on methods of plant breeding, classification of breeding methods, methods of breeding for self-pollinated,cross-pollinated and asexually propagated species, a brief account of breeding methods

1. : Methods of plant breeding, classification of breeding methods , methods of
breeding for self pollinated ,cross pollinated and asexually propagated species ,
brief account of breeding methods.
Submitted to: Submitted
by:
Dr. Kaushik Kumar Panigrahi Saroj
Kumar Jena
Asst. Prof.( Plant Breeding & Genetics) Adm. No:
08 HO/16

2. INTRODUCTION
• Plant breeding is an art or science as old as agriculture started
since man learnt to cultivate the plants.
• plant breeding is considered as the current phase of crop
evolution.
• Selection of desired plants even today is an art which depends on
the skill of a person but skill alone is not enough.
• Modern plant breeding is based on thorough understanding and
use of genetic principles

3. METHODS OF BREEDING IN SELF
POLLINATED SPECIES
• 1) Introduction and Acclimatization:
• The main objective of plant breeding is to produce the new varieties, which superior
in all aspects than the existing one. The principle methods of breeding self
pollinated crops are:
• 2) Selection: a) Pure Selection b) Mass selection
3) Hybridization: a) Pedigree method b) Bulk population method.
c) Back cross method d) Multiple crossing.
• 4) Other Method: a) Multiline varieties b) Single seed descent method
c) Hybrids d) Population approach
• 5) Mutation Breeding:
• 6) Polyploidy Breeding:

4. PLANT INTRODUCTION AND
ACCLIMATIZATION
• Taking a genotype or a group of genotypes in to a new place or environment where they
were not grown previously. Thus introduction may involve new varieties of a crop already
grown in that area, a wild relative of the crop species or totally a new crop species for that
area.
• When superior cultivars from neighboring or distant regions are introduced in a new area,
they generally fail initially to produce a phenotypic expression similar to that in their place
of origin. But later on they pickup and give optimal phenotypic performance, in other words
they become acclimatized to the new ecological sphere. Thus acclimatization is the ability of
crop variety to become adapted to new climatic and edaphic conditions

5. PURELINE SELECTION
• Pureline Selection A large number of plants are selected from a self
pollinated crop. The selected plants are harvested individually. The selected
individual plants are grown in individual rows and evaluated and best
progeny is selected, yield tested and released as a variety.

6. MASS SELECTION
• Here a large number of plants having similar phenotype are selected and their
seeds are
• mixed together to constitute a new variety. Thus the population obtained-from
selected plants
• will be more uniform than the original population. However they are
genotypically different

7. HYBRIDIZATION
• The production of a hybrid by crossing two individuals of unlike
genetical constitution 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.
• Objectives of Hybridization:
• I. To artificially create a variable population for the selection of
types with desired combination of characters.
• II. To combine the desired characters into a single individual, and

8. MUTATION BREEDING
This aims at accelerating the process of developing different traits
for selection, such as disease resistance, tolerance to harsh growing
conditions, and other valuable agronomic traits. It does not involve
gene modification, also known as gene splicing. Mutation breeding
uses a plant’s own genetic resources mimicking the process of
spontaneous mutations, that’s under way in nature all the time, the
basis of evolution. Importantly it broadens biodiversity.
• Mutation breeding is built on mutation induction and mutation
detection. Mutation induction coupled with selection remains the
"cleanest" and most inexpensive way to create varieties by
changing single characters without affecting the overall phenotype.

9. BREEDING METHODS IN CROSS POLLINATED
SPECIES
• Mass selection
• Development of hybrid varieties
• Development of synthetic varieties

10. MASS SELECTION
• Mass selection in cross-pollinated species takes the same form as in
self-pollinated species; i.e., a large number of superior appearing
plants are selected and harvested in bulk and the seed used to produce
the next generation. Mass selection has proved to be very effective in
improving qualitative characters, and, applied over many generations, it
is also capable of improving quantitative characters, including yield,
despite the low heritability of such characters. Mass selection has long
been a major method of breeding cross-pollinated species, especially in
the economically less important species.

11. HYBRID VARIETIES
• The outstanding example of the exploitation of hybrid vigour through the use of F1
hybrid varieties has been with corn (maize). The production of a hybrid corn variety
involves three steps: (1) the selection of superior plants; (2) selfing for several
generations to produce a series of inbred lines, which although different from each
other are each pure-breeding and highly uniform; and (3) crossing selected inbred
lines. During the inbreeding process the vigour of the lines decreases drastically,
usually to less than half that of field-pollinated varieties. Vigour is restored, however,
when any two unrelated inbred lines are crossed, and in some cases the F1 hybrids
between inbred lines are much superior to open-pollinated varieties. An important
consequence of the homozygosity of the inbred lines is that the hybrid between any
two inbreds will always be the same. Once the inbreds that give the best hybrids have
been identified, any desired amount of hybrid seed can be produced.

12. SYNTHETIC VARIETIES
• A synthetic variety is developed by intercrossing a number of
genotypes of known superior combining ability—i.e.,genotypes that
are known to give superior hybrid performance when crossed in all
combinations. (By contrast, a variety developed by mass selection is
made up of genotypes bulked together without having undergone
preliminary testing to determine their performance in hybrid
combination.) Synthetic varieties are known for their hybrid vigour
and for their ability to produce usable seed for succeeding seasons.
Because of these advantages, synthetic varieties have become
increasingly favored in the growing of many species, such as the
forage crops, in which expense prohibits the development or use of
hybrid varieties.

13. ASEXUAL PROPAGATION METHODS
• The major methods of asexual propagation are cuttings, layering,
division, and budding grafting. Cuttings involve rooting a severed
piece of the parent plant; layering involves rooting a part of the
parent and then severing it; and budding and grafting is joining
two plant parts from different varieties.

14. PROPAGATION BY CUTTINGS
• Many types of plants, both woody and herbaceous, are frequently propagated
by cuttings. A cutting is a vegetative plant part which is severed from the
parent plant in order to regenerate itself, thereby forming a whole new plant.
Take cuttings with a sharp blade to reduce injury to the parent plant. Dip the
cutting tool in rubbing alcohol or a mixture of one part bleach to nine parts
water to prevent transmitting diseases from infected plant parts to healthy
ones. Remove flowers and flower buds to allow the cutting to use its energy
and stored carbohydrates for root and shoot formation rather than fruit and
seed production.

15. PROPAGATION BY LAYERING
• Stems still attached to their parent plants may form roots where they touch a
rooting medium. Severed from the parent plant, the rooted stem becomes a
new plant. This method of vegetative propagation, called layering, promotes a
high success rate because it prevents the water stress and carbohydrate
shortage that plague cuttings.
• Some plants layer themselves naturally, but sometimes plant propagators
assist the process. Layering may be enhanced by wounding one side of the
stem or by bending it very sharply. The rooting medium should always provide
aeration and a constant supply of moisture.

16. PROPAGATION BY GRAFTING
• Grafting is an advanced technique that botanists, farmers, gardeners, and
hobbyists use to add living tissue from one plant to another. Plant tissues
have the ability to grow new vascular tissue, and the process of grafting takes
advantage of this ability. The vascular tissue of the main plant joins with the
vascular tissue of the added plant, keeping the new tissue alive and growing.
This is a way for plants to reproduce asexually. You can think of grafting as
being similar to organ donation - when someone needs a new kidney or liver,
they can get one donated.

17. PROPAGATION BY BUDDING
• Budding is the vegetative method of plant propagation and can be
defined as “ an art of insertion of a single mature bud in to the stem of
the rootstock in such way that the union takes place and the
combination continues to grow. It is grafting of a single individual bud
instead of whole bud stick on scion as in done in case of grafting.
• There are several techniques or methods of insertion of bud in to the
root stock. The adoption of any of the methods like grafting depends
upon the plants to be budded, situation, facilities and source available
etc.

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