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Breeding methods in cross pollinated crops
1. Breeding methods in Cross pollinated crops
Mass selection - Ear to row method and
Progeny selection schemes
Submitted by
J Venkata Yashwanth
TAM/2019-042
ACHARYA N G RANGA AGRICULTURAL
UNIVERSITY
S.V. Agricultural college, Tirupati
Dept. of Genetics and Plant breeding
2. Breeding methods in cross
pollinated crops
Cross pollinated crops are highly heterozygous and
heterogeneous
They have random mating and maintain deleterious
genes in the population
More adaptability and flexibility to the environment
Heterosis can be fully exploited
Inbreeding depression can be seen which makes it
difficult for fixing of desirable genes
In CP crops genotype of individual is seldom important
and breeder tries to increase the frequency of desirable
alleles or genes in population
4. Population improvement
In cross pollinates crops for population improvement
three breeding approaches are made
Recurrent selection
Disruptive mating
Biparental mating
5. Mass selection
Mass selection consists of selecting individuals on the basis of
phenotypic superiority and mixing the seeds for using as planting
material for next season.
It is the earliest method of selection.
Mixture of homo and heterozygotes and heterogeneous
Further selection of mass selected varieties of cross pollinated crops
lead to inbreeding depression
Broad genetic base and good adaptability
7. There are two kinds of mass selection:
Negative mass selection
only undesirable plants are removed from field and rest are allowed to
grow.
usually used for purification in seed production and certification
programs
Positive mass selection
Desired plants are selected and allowed to grow for further
Base material here is old varieties or land races
8. Merits
Can be practiced both in self and cross pollinated crops.
The varieties developed through mass selection are
more widely adopted than pure lines.
It retains considerable variability and hence further
improvement is possible in future by selection.
Useful for purification of pure line varieties.
Improvement of characters governed by few genes with
high heritability is possible.
Less time consuming and less expensive
9. Demerits
Varieties are not uniform.
Since no progeny test is done, the genotype of the
selected plant is not known.
Since selection is based on phenotype and no control
over pollination the improvement brought about is not
permanent.
It can not create any new genotype but utilizes existing
genetic variability.
Characters which are governed by large number of
genes with low heritability can not be improved.
11. Progeny selection schemes
Ear to row meted and its modification
Recurrent selection
Simple Recurrent selection
Reciprocal Recurrent selection
Recurrent selection for GCA and SCA
Marker assisted Recurrent selection
12. Ear to row method
This method was developed by Hopkins in 190 and used
more in maize
Selection is based on progeny test not based on
phenotype
Mostly Selection is based on maternal parental
Inbreeding depression can be avoided
Each selection cycle has generally 2 years
15. Merits
Selection is based on progeny test not merely on basis of
phenotype
Inbreeding is possible per each selection cycle
Method is easy and simple
16. Demerits
No control on pollination and selection based on
maternal parent
Superior progenies re pollinated by both superior and
inferior progeny
17. Modification of ear to row
method
First year – several plants are selected based on
phenotypes and open pollinated seed is harvested
separately
Second year – small progeny rows are grown visually
evaluated and superior ones are identified. Remaining
seed from selected plants is kept separately
Third year – remaining seeds are bulked and planted
they are allowed to open pollinate and selection cycle
can be repeated with same process
18.
19. S1 and S2 progeny testing
When seeds for progeny testing are obtained by selfing
of selected plants rather than open pollination then it is
called S1 progeny testing
When seeds for progeny testing are obtained by selfing
of selected plants for two generations rather than open
pollination then it is called S2 progeny testing
20. Line breeding
A system of breeding in which a number of genotypes
with superior performance for several characters are
bulked to form a variety
Commonly used in animal breeding and in crops for CP
crops
May involve cross between closely related ones but not
continuous
Useful to transmit a large proportion of desirable genes
from generation to generation
Line breeded varieties have to be maintained by open
pollination