Breeding self pollinated crops

Breeding self pollinated crops

1. 1Prepared by
Pawan Kumar Nagar
repaed bywnKduanmNamg
Prepared by
Pawan Kumar Nagar
M.Sc. (Fruit science)
Breeding Breeding
Self Pollinated CropsSelf Pollinated Crops

2. General methods: Special methods:
1.Plant introduction 1. Mutation breeding
2. Pureline selection 2. Polyploidy breeding
3. Mass selection 3. Transgenic breeding
4. Pedigree method 4. Molecular breeding
5. Bulk method
6. Single Seed descent method
7. Back cross method
8. Hetrosis breeding

3. Symbols for basic crosses
F: The symbol F (for filial) denotes the progeny of a
cross between two parents.
 : The symbol is the notation for selfing.
S: The S notation is also used with numeric subscripts.
In one usage S
0
= F
1
; another system indicates S
0
= F
2
.

4. Pureline refers to the homogenous progeny of a
self pollinated homozygous plant.
 Mass selection is a method of breeding in which
individual plants are selected on the basis of
phenotype from a mixed population , their seeds
are bulked and used to grow the next generation.
The deliberate mixture of isolines, closely related
lines or unrelated lines are referred to as
multilines, and the method of developing a
variety from any of these mixtures is known as
multiline breeding.

5. Pure line selection Pure line selection

6. Johannsen (1903,1926), a Danish biologist,
developed the concept of pureline theory
working with Princess variety of common
bean(Phaseolus vulgaris).

7. Key features:
1.Homogeneous
2.Nonheritable variation
3.Highly uniform
4.Selection is ineffective
5.Narrow adaptation
6.More prone to new diseases
7.Isolation of pure lines
8.Sources of variation

8. Applications
Pure-line breeding is desirable for developing cultivars for certain
uses:
1.Varieties for mechanized production that must meet a certain
specification for uniform operation by farm machines.
2.for a discriminating market for visual appeal (e.g., uniform
shape, size).
3.for the processing market (e.g., demand for certain canning
qualities).
4.Advancing that appear in a population (e.g., a mutant flower for
ornamental use).
5.Improving newly domesticated crops that have some variability.

10. Advantages:
1.It is a rapid breeding method.
2.The method is inexpensive to conduct.
3.The variety developed by this method has great “eye
appeal” because of the high uniformity.
4.It is applicable to improving traits of low heritability,
because selection is based on progeny performance.
5.Only the best pure line is selected for maximum
genetic advance.

11. Disadvantages
1.The purity of the variety may be altered through
admixture, natural crossing with other varieties and
mutations.
2.Narrow genetic base and so poor adaptability.
3.A new genotype is not created.
4.The method promotes genetic erosion
5.Progeny rows take up more resources (time, space).
6.Only applicable to self pollinated species.

12. Mass selectionMass selection

13. As an ancient art, farmers saved seed from
desirable plants for planting the next season’s
crop, a practice that is still common in the
agriculture of many developing countries.
Mass selection is often described as the oldest
method of breeding self-pollinated plant
species.
This method of selection is applicable to both
self- and cross-pollinated species. But it is more
used for cross-pollinated crops.

14. Key features
The purpose of mass selection is population improvement
through increasing the gene frequencies of desirable genes.
Selection is based on plant phenotype.
Mass selection is imposed once or multiple times (recurrent mass
selection).
The improvement is limited to the genetic variability that existed
in the original populations.
The goal in mass selection is to improve the average
performance of the base population.

15. 1. Positive mass selection:
 Desirable plants are selected from a mixed
population.
Base material is old varieties or land races.
2. Negative mass selection:
Undesirable off type plants are removed from a
mixed population.
used for varietal purification in seed production
and certification programs.

16. The success of mass selection mainly
depends on three factors:
1.Variability in the base population.
2. Mode of inheritance of the character to be
improved.
3. Heritability of the character.

17. There are two defects of mass selection:
1. No control on pollination.
2. Selection is based on phenotype.
Modifications are;
1. Rejection of inferior plants.
2. Use of composite pollen.
3. Stratification of field.

18. Cultivar development procedure

19. Purification of an existing cultivar

20. Applications
1.to maintain the purity of an existing variety that has become
contaminated.
2.to develop a variety from a base population created by
hybridization.
3.to preserve the identity of an established variety or soon-to-be-
released new variety.
4.Some breeders use mass selection as part of their breeding
program to rogue out undesirable plants, thereby reducing the
materials advanced and saving time and reducing costs of
breeding.

21. Advantages
1.It is rapid, simple, and straightforward.
2.It is inexpensive to conduct.
3.The variety is phenotypically fairly uniform even though it is
a mixture of pure lines.
Disadvantages
1.The traits of interest should have high heritability.
2.Less phenotypic uniformity than other procedures.
3.With dominance, heterozygotes are indistinguishable from
homozygous dominant genotypes.

22. 22
MASS SELECTION VS PURE LINE MASS SELECTION VS PURE LINE
SELECTIONSELECTION
Line mixtureLine mixture
Bulk of Bulk of
phenotypicallyphenotypically
similar plantssimilar plants
Cultivar registerCultivar register
and marketingand marketing
Single plant offspringsSingle plant offsprings
L1 L2 L3……. LNL1 L2 L3……. LN
Register and marketRegister and market
the best pure linesthe best pure lines
Mass selectionMass selection Pure line selectionPure line selection
Heterogenous cultivarsHeterogenous cultivars Homogenous cultivarsHomogenous cultivars
Line mixtureLine mixture
Bulk of Bulk of
phenotypicallyphenotypically
similar plantssimilar plants
Cultivar registerCultivar register
and marketingand marketing
Single plant offspringsSingle plant offsprings
L1 L2 L3……. LNL1 L2 L3……. LN
Register and marketRegister and market
the best pure linesthe best pure lines
Mass selectionMass selection Pure line selectionPure line selection
Heterogenous cultivarsHeterogenous cultivars Homogenous cultivarsHomogenous cultivars
Line mixtureLine mixture
Bulk of Bulk of
phenotypicallyphenotypically
similar plantssimilar plants
Cultivar registerCultivar register
and marketingand marketing
Single plant offspringsSingle plant offsprings
L1 L2 L3……. LNL1 L2 L3……. LN
Register and marketRegister and market
the best pure linesthe best pure lines
Mass selectionMass selection Pure line selectionPure line selection
Heterogenous cultivarsHeterogenous cultivars Homogenous cultivarsHomogenous cultivars

23. MULTILINE
BREEDING

24. Multilines:
First Suggested IN OATS BY JENSEN IN 1952
Multilines are developed for self-pollinating species.
These cultivars consist of a mixture of specially developed
genotypes called isolines (or near isogenic lines) because they differ
only in a single gene (or a defined set of genes).
Isolines are developed primarily for disease control, even though
these cultivars could, potentially, be developed to address other
environmental stresses.
Isolines are developed by using the techniques of backcrossing in
which the F1 is repeatedly crossed to one of the parents (recurrent
parent) that lacked the gene of interest (e.g., disease resistance).

25. 1. Mixtures of isolines.
2. Mixture of closely related lines.
3. Mixture of unrelated or distinctly
different genotypes.

26. 1.It has genetic diversity.
2.It should have normal resistance.
3.Components should be uniform
agrnomically.
4.It should have yield advantage.

27. 1. Selection of recurrent parent.
2. Selection of donor parents.
3. Transfer of resistance.
4. Mixing of isolines.

28. 1.Identical to recurrent parent
2.Loss to cultivator is low.
3.Spreading of diseases is slow
4.It reduces the risk of homogenising the
pathogen population globally.
5.Stabilises and optimizes production on
farm.

29. 1. Seed is to be repaced every few years.
2. Production and mainatenance is time taking
job.
3. It has to be regularly reconstituted, and new
lines have to be continuously developed.
4. Seed certification poses difficulties.
5. It is less attractive, less uniform and costly
method.

30. Multiline cultivars have been developed for
commercial cultivation in oats, wheat,
soybean and peanut in USA.
In India three multiline varieties, viz.
KSML 3, MLKS 11 and KML 7404 have
been released in wheat from Punjab.