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6. mass selection
1.
2. Presented by
Patel Yogesh D.
M. Sc. (Agri.),2nd Semester
Reg. No. :04-AGRMA-01404-2015
“An
Assignment
on
“ Mass selection method in plant breeding’’
2
3. Mass selection refers to a methods of crop
improvement in which individual plants are
selected on the basis of phenotype from a mixed
population, their seeds are bulked and used to
grow next generation.
The oldest methods of crop improvement
Applicable to both self and cross pollinated
species.
Mass selection
4. 1) To increase the frequency of superior
genotypes from a genetically variable
population
2) Purify a mixed population with differing
phenotypes
3) Develop a new cultivar by improving the
average performance of the population
Objective
5. 1. Genetic constitution :-
Self pollinated crops:- A mass selected variety is
homozygous but heterogeneous because it is mixture of
several pure line.
Cross pollinated crops:- variety is mixture of homozygous
and heterozygous and variety is heterogeneous.
2. Adaptation:-
Mass selected varieties have wide adaptation.
Varieties are more stable against environmental changes.
Heterogeneity provides better buffering capacity.
Mass selected varieties have broader genetic base.
Adaptability is more in cross pollinated crops than in self
pollinated crops.
Main features
6. 3. Variation:-
They are composed of several pure line in self pollinated
crops and of several homo and heterozygous genotypes in
cross pollinated crops.
There is heritable variation in the mass selected varieties.
The heritable variation provides them good buffering
capacity.
4. Selection:-
Selection is effective due to presence of heritable variation.
5. Quality:-
A variety developed by mass selection is less uniform in the
quality of seed than pure lines due to presence of heritable
variation.
7. 6. Resistance :-
Mass selected varieties are less prone to the
attack of new disease due to genetic diversity.
They are more resistance or tolerant to new
disease.
7. Maintenance:-
Periodic removal of off type plants is
essential to maintain the yield of mass
selected varieties.
8. Used in both self and cross pollinated crops
Self pollinated:
• Mass selection variety is a mixture of several
pure lines.
• Constitutes a homozygous but heterogeneous
population.
Cross pollinated:
• A mass selected variety is mixture of several
homozygote and heterozygote.
• Variety is a heterozygous and heterogeneous.
Genetic Basis
9. • Positive mass selection:
Desirable plants are selected from a mixed population.
Their seeds are mixed together to grow further
generation.
This process is continued for several years.
Old varieties or land races are used as the base material.
• Negative mass selection:
Only undesirable off types of plants are removed from
the field and rest are allowed to grow.
Generally used for Varietal purification in seed
production.
Helps in maintaining high level of genetic purity.
Types of mass selection
10. The success of mass selection depends
on
Variability in base population.
Mode of inheritance of characters to be
improved.
Heritability of the characters.
Oligogenic recessive characters than
polygenic characters.
11. The local varieties are mixtures of several genotypes,
which may differ in flowering or maturity plant height,
disease resistant etc.
Many of these plants type would be inferior and low
yielding, such plants will be eliminated through mass
selection and local variety would be improved without
adversely affecting its adaptability and stability.
Because the new variety would be made up of the most
of the superior plants type present in the original local
variety.
1. Improvement of Desi or local variety
Application of mass selection.
12. 2. Purification the existing pure line variety.
Pure lines tend to become variable with time due
to mechanical mixtures, natural hybridization,
mutation etc. therefore, it is necessary that the
purity of pure line varieties be maintained
through regular mass selection.
Mass selection is generally important and
practised in cross-pollinated crop and has the
only limited application in self pollinated crop.
13. Selection of base population.
Selection of desirable plants from the base
population.
Mixing their seeds to raise next generation.
Evaluation in field trials.
Releasing as a new variety.
Steps of Mass selection:-
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First
year
second
year
Third to
fifth year
sixth
year
i. From a variable population, 200-2000 plants
with similar but desirable traits are selected
ii. The seed from selected plant are composited
i. The composited seed is planted in a
preliminary yield trial along with standard
checks
ii. Phenotype of the selected population is
clearly evaluated
i. Promising selections are evaluated in
coordinated yield trials at several locations
ii. It out standing raised as a new variety.
Seed multiplication for distribution.
16. Good method for old and land races varieties.
Good for purification of improved variety.
More stable then pure lines due to heterogeneity.
Good protection again disease and pest.
Simple and quick method for improvement.
Applicable in self and cross pollinated species.
MERIT
17. The developed through mass selection so variation and are not
uniform as pure line variety.
The improvement through mass selection is generally less than
that could be achieved through pure line selection.
In the absence of progeny test, it is not possible to determine if
the selected plant are homozygous.
Due to the popularity of pure line variety, mass selection is not
commonly use for improvement of self pollinated crop.
DEMERIT
18. Variety develop by mass selection are more
difficult to identified then pure line variety in seed
certification programmes.
Mass selection can not generated variability.
DEMERIT
20. 1. Rejection of inferior plants:- Inferior
plant are removed before flowering.
2. Use of composite pollen:-pollen are
collected then bulked.
Modification of mass selection
21. Also known as grid method of mass
selection
This method is suggested by Gardner in
1961
Field is divided into several small plots,
e.g., having 40-50 plants each.
Superior plant are selected in each
small plot.
Seeds are selected and composite to
raise the next generation.
3) Stratification of field-
22. A single cross hybrid, are planted as checks after
every one, two or four plants of the variety under
selection.
The yields of plants under selection are expressed as
under selection are expressed as per cent of the yield
of the yield of nearest check plant.
This scheme is designed to minimise the
environmental influence on the yields of plants
being selected.
And employs the principle of contiguous control.
4). Plant of single genotype
23. • Mass selection is based on only
phenotypic performance.
• Mass selection used in self pollinated as
well as cross pollinated crop.
• Mass selection is used for the
improvement of local or desi varieties.
Conclusion