Breeding methods in cross pollinated crops with major emphasis on population improvement

2. Doctoral Seminar Presentation
“BREEDING METHODS IN CROSS POLLINATED CROPS WITH
MAJOR EMPHASIS ON POPULATION IMPROVEMENT”
Presented by
Mr. VINOD SHRIPATI PAWAR
Reg.No.2017/07
Seminar Incharge
Dr. G. C. SHINDE
Assistant Professor,
Department of Agricultural Botany,
MPKV, Rahuri.
Research Guide
Dr. C. B. SALUNKE
Associate Professor,
Department of Agricultural Botany,
MPKV, Rahuri.
Course number: GP- 691
Course Title : Doctoral Seminar I
Submitted to
Department of Agricultural Botany,
Post Graduate Institute,
Mahatma Phule Krishi Vidyapeeth,
Rahuri.413722
2019

3. INTRODUCTION
BREEDING METHODS
POPULATION IMPROVEMENT
CASE STUDY
CONCLUSION.

4. Various approaches (viz., selection, hybridization, mutation,
etc.) that are used for genetic improvement of crop plants are
referred to as plant breeding methods or plant breeding
procedures or plant breeding techniques.
Plant breeding methods are generally classified on the basis of
application of crop improvement (general methods, special
methods and population improvement approaches) and
hybridization.
Population of cross pollinated crops are highly heterozygous
as well as heterogeneous.

5. When inbreeding is practiced, they show severe
inbreeding depression.
They show variable inbreeding depression,
ranging from low to very severe.
So to avoid inbreeding depression and its
undesirable effects, the breeding methods in the
crop is designed in such a way that there will be
a minimum inbreeding.

6. BREEDING METHODS FOR CROSS POLLINATED CROP
I. General methods
(1) Plant introduction
(2) Mass and progeny selection
(3) Backcross method
(4) Heterosis breeding
(5) Synthetic breeding
(6) Composite breeding
II. Special methods
(1) Mutation breeding
(2) Polyploidy breeding
(3) Transgenic breeding
(4) Molecular breeding.

7. A. Selection
a. Mass selection
b. Modified mass selection i. Detasseling ii.Panmixis
iii. Stratified or grid or unit selection or Contiguous control.
B. Progeny testing and selection
a. Half sib family selection
i. Ear to row
ii. Modified ear to row.
b. Full sib family selection.
c. Inbred or selfed family selection.
i. Sl self family selection
ii.S2 self family selection.
C. Recurrent selection
a. Simple recurrent selection
b. Recurrent selection for GCA
c. Recurrent selection for SCA
d. Reciprocal recurrent selection.
D. Hybrids
E. Synthetics and Composites.

8. Plant introduction consists of taking a genotype or a
group of genotypes of plants into new environments
where they were not being grown before.
It is an oldest and rapid method of crop improvement.
Agencies in India
All the introductions in India must be routed through
the NBPGR, New Delhi.
On the basis of climatic zones of India
 1.Simla. It is situated in Himachal Pradesh and
represents the temperate zone
 2. Jodhpur, Rajasthan. It represents the arid zone
 3. Kanya Kumari, Tamil Nadu. It represents the
tropical zone
 4. Akola, Maharashtra. It represents the mixed
climatic zone. It was recently shifted from Amravati.
 5. Shillong, Meghalaya
1. PLANT INTRODUCTION:

9. STEPS OF INTRODUCTION:
 Procurement
 Quarantine
 Cataloguing
 Evaluation
 Multiplication and Distribution
PURPOSE
The main purpose of plant introduction is to improve the plant
wealth of the country.
The chief objectives
To Obtain An Entirely New Crop Plant.
To Serve as New Varieties.
To Be Used in Crop Improvement.
To Save the Crop from Diseases And Pests.
For Scientific Studies.

10. Primary Introduction :
When the introduced variety is well suited to
the new environment, it is released for commercial
cultivation without any alteration in the original genotype,
this constitutes primary introduction.
Primary introduction is less common, particularly in
countries having well organized crop improvement
programmers.
Secondary Introduction:
The introduced variety may be subjected to
selection to isolate a superior variety. Alternatively, it may be
hybridized with local varieties to transfer one or few
characters from this variety to the local ones these processes
are known as secondary introduction.
Secondary introduction is much more common than primary
introduction.

11. Merits of Plant Introduction
1. It provides entirely new crop plants.
2. It provides superior varieties either directly or after
selection & hybridization.
3. Introduction and exploration are the only feasible
means of collecting germplasm and to protect variability
from genetic erosion.
4. It is very quick & economical method of crop
improvement, particularly when the introductions are
released as varieties either directly or after a simple selection.
5. Plants may be introduced in new disease free areas to
protect them from damage.
Demerits of Plant Introduction
The disadvantages of plant introduction are associated with
chances the introduction of weeds, diseases and pests.

12. 2. Backcross Breeding
This method 1st proposed by : Harlan & Pope (1922)
Back cross : A cross between a hybrid (F1 or a segregating
generation) and one of its parents is known as backcross.
Back cross method : In the B.C. method, the hybrid and the
progenies in the subsequent generations are repeatedly back
crossed to one of their parents.
Objective : To improve or correct one or two specific defects of
a high yielding variety, which is well adapted to the area and
has other desirable characteristics.
Recipient parent : Well adapted, high yielding variety, lacking
one or two characters and hence receives these genes from
other variety.
Donor parent : The variety which donates one or two useful
genes.
Recurrent parent : Since the recipient parent is repeatedly
used in the backcross programme, it is also known as the
recurrent parent.
Non-recurrent parent : The donor parent, on the other hand,
is known as the non-recurrent parent because it is used only
once in the breeding programme (for producing the F1 hybrid).

13. Let us suppose that a high yielding and widely adapted variety A is
susceptible to stem rust. Another variety B is resistant to stem rust,
and that resistance to stem rust is dominant to susceptibility.
Hybridization : Variety A is crossed to variety B. Generally, variety
A should be used as the female parent. This would facilitate the
identification of selfed plants, if any.
F1 Generation : F1 plants are backcrossed to variety A. Since all
the F1 plants will be heterozygous for rust resistance, selection for
rust resistance is not necessary.
First Backcross Generation (BC1) : half of the plants would be
resistant and the remaining half would be susceptible to stem
rust. Rust resistant plants are selected and backcrossed to variety A.
BC1 plants resistant to rust may be selected for their resemblance to
variety A as well.
BC2-BC5 Generations : In each backcross generation, segregation
would occur for rust resistance. Rust resistant plants are selected and
backcrossed to the recurrent parent A. Selection for the plant type of
variety A may be practiced, particularly in BC2 and BC3.
Transfer of a Dominant Gene

14. BC6- Generation : On an average, the plants will have
98.4 per cent genes from variety A. Rust resistant plants
are selected and selfed; their seeds are harvested
separately.
BC6 F2 Generation : Individual plant progenies are
grown. Progenies homozygous for rust resistance and
similar to the plant type of variety A are harvested in bulk.
Several similar progenies are mixed to constitute the new
variety.
Yield Tests : The new variety is tested in a replicated
yield trial along with the variety A as a check. Plant type,
date of flowering, date of maturity, quality etc. are
critically evaluated.
Ordinarily, the new variety would be identical to the
variety A in performance. Detailed yield tests are,
therefore, generally not required and the variety may
directly be released for cultivation.

16. When rust resistance is due to a recessive gene, all the backcrosses
cannot be made one after the other. After the first backcross, and after
every two backcrosses, F2 must be grown to identify rust resistant
plants. The F1 and the backcross progenies are not inoculated with rust
because they would be susceptible to rust. Only the F2 is tested for
rust resistance.
Hybridization : The recurrent parent is crossed with the rust
resistant donor parent. The recurrent parent is generally used as the
female parent.
F1 Generation : F1 plants are backcrossed to the recurrent parent.
BC1 Generation : Since rust resistance is recessive, all the plants
will be rust susceptible. Therefore, there is no test for rust resistance.
BC1F2 Generation : Plants are inoculated with rust spores. Rust
resistant plants are selected and backcrossed with the recurrent parent.
Selection is done for the plant type and other characteristics of the
variety A.
BC2 Generation :There is no rust resistance test. Plants are selected
for their resemblance to the recurrent parent A, and backcrossed with
the recurrent parent.
Transfer of a Recessive Gene

17. BC3 Generation : There is no disease test. The plants are self-pollinated
to raise F2. selection is usually done for the plant type of variety A.
BC3F2 Generation : Plants are inoculated with stem rust. Rust resistant
plants resembling variety A are selected and backcrossed to variety A.
Selection for plant type of A is generally effective.
BC4 Generation : There is no rust resistance test. Plants are back-
crossed to variety A.
BC5 Generation : There is no rust test. Plants are self -pollinated to
raise F2 generation.
BC5F2 Generation : Plants are subjected to rust epidemic. A rigid
selection is done for rust resistance and for the characteristics of variety
A. Selfed seeds from the selected plants are harvested separately.
BC5F3 Generation : individual plant progenies are grown and subjected
to rust epiphytotic. A rigid selection is done for resistance to stem rust
and for the characteristics of variety A. Seeds from several similar rust
resistant homogeneous progenies are mixed to constitute the new
variety.
Yield Tests : It is the same as in the case of transfer of a dominant gene.

19. Achievements
Name of pearl millet parental line
ICMA 99011
ICMA 99012
ICMA 99013
ICMA 99014
ICMA 99015
ICMA 99016
ICMA 99017
Conventional backcrossing at ICRISAT of DM
resistance from ICML 22
Bajra : MS 521, MS 541A, MS 570A

20. Merits and Demerits of Back cross breeding
Merits:
1. Back cross method retains all desirable character of a popular
adapted varieties and replaces undesirable allele at particular locus
2. Useful for the transfer of disease resistance and incorporation of
quality traits into a variety
3. This is used for the development of isogenic lines,
4. Extensive tests are not required 2-3 generation can be raised in
off season nurseries green houses, it would save time.
5. This is the only method for the inter specific gene transfer and
transfer of cytoplasm.
6. Male sterility and fertility restoration genes can be transferred to
various back ground.
Demerits:
1. New variety cannot be superior to recurrent parent except for the
character transferred
2. It involves lot of crossing work. 6-8 back cross is often difficult
and time consuming.
3. Sometime undesirable gene linked with desirable also may be
transferred.
4. By the time the back cross programme the recurrent parent may
have been replaced by other varieties superior in yield and other
character.

21. 3. PEDIGREE METHOD
In the pedigree method, individual plants are selected from
F2 and subsequent generations, and their progenies are tested.
During the entire operation a record of all parent off spring
relationships is kept. This is known as pedigree record.
Individual plant selection is continued till the progenies
show no segregation. At this stage the selection is done among
the progenies, multilocation tests are conducted and released
as varieties.

22. 1st year : cross is made between the parents possessing desirable
characters.
2nd year : Sow the F1 seed giving wide spacing so that each F1 plant
produces more seeds. Raise as many F1 plants as possible to produce large
number of F2 seeds. Harvest in bulk.
3rd year : Grow 2000-10000 plants of F2 giving wide spacing for full
expression of the characters in F2 generation plants. Grow parents for
comparision. Depending upon the facilities and objectives of the
programme about 100-500 superior plants are selected. The value of
selection depend on the skill of the breeder. He has to judge which F2 plant
will produce superior progeny for characters under consideration. The
breeder develops this skill through close study of the crop for many
generations. The selection in F2 is done for simply inherited characters like
head type disease resistance etc. and selection for characters governed
by many genes like yield will be reserved for later generations. The
selected plants are harvested separately and given serial numbers and
description entered in pedigree registers.
4th year : Progeny rows of F3 i.e. seeds of one selection plant in one row
are space planted along with parents and checks. From superior progeny
rows, individual plants with desirable characters are selected (about 50-
100 families and about 5 plants in each family and harvested
separately). Diseased, lodging and undersirable progenies are discarded.

23. 5th year : F4 plants raised again as head to row. Desirable plants are
selected from desirable rows and harvested separately.
6th year : F5 plants raised in 3 row plots i.e. seeds of each selected plant
sown in 3 rows. By this time many families might have become reasonly
homozygous. For comparision check variety is grown for every 3 or 5
block. Progenies are evaluated for yield and the inferior ones are
rejected. The number should be reduced to 25-50. superior plants from
superior progenies are selected. Plants from each progeny are bulked.
7th year : F6 individual plant progenies are grown in multi-row plots and
evaluated. Inferior progenies are rejected and superior progenies are
selected. Plants of each progeny are harvested in bulk. Diseased and
inferior plants from the progenies are removed.
8th year : F7 preliminary yield trial with 3 or more replications ar
conducted to identify superior lines. The progenies are evaluated for
many characters including yield. Standard commercial varieties must be
included as checks. Two to five outstanding lines are selected and
advanced to coordinated yield trials.
9th, 10 th & 11th year : selected lines are tested in several
localities for 2 or 3 years for adaptation tests. Lines are evaluated for all
characters mainly yield and disease resistance. A line that is superior to
commercial variety in yield and other characters is selected.

24. 11th and 12th year : Selected superior lines is named, multiplied
and released as a new variety. Number of year can be reduced if
generations are advanced during off seasons either in green house
or under irrigated conditions.

26. Merits of pedigree method :
1. It gives maximum opportunity for the breeder to use his skill and
judgement in selection of plants
2. It is well suited for the improvement of characters which can be easily
identified and are simply inherited.
3. Transgressive segregation for yield and other quantitative characters
may be recovered.
4. Information about the inheritance of characters and pedigree of lines
can be obtained.
5. Inferior plants and progenies are eliminated in early generations.
6. It takes less time than bulk method to develop new variety.
Demerits of pedigree method :
1. Valuable genotypes may be lost in early generations, if sufficient skill
and knowledge are lacking in the breeder, at the time of selection.
2. No opportunity for natural selection
3. Difficult to handle many crosses
4. Maintenance of records, selections, growing progeny rows etc are time
consuming and laborious.
Achievements : Large number of varieties have been developed by pedigree
method in
many crops.
Cotton – Lakshmi, Digvijay,

27. Heterosis breeding
Tem heterosis used by Shull 1914.
Heterosis is the superiority of a hybrid over its parents.
Cross-pollinated species show heterosis, particularly when inbred
lines are used as parents.
1. Increased yield. Heterosis is generally expressed as an increase
in the yield of hybrids.
2. Increased Reproductive Ability. The hybrids exhibiting
heterosis show an increase in fertility or reproductive ability.
3. Increase in Size and General Vigour. The hybrids are generally
more vigorous, i.e., healthier and faster growing and larger in size
than their parents.
4. Better Quality. In many cases, hybrids show improved quality.
5. Earlier Flowering and Maturity. In many cases, hybrids are
earlier in flowering and maturity than the parents.
6. Greater Resistance to Diseases and Pests. Some hybrids are
known to exhibit a greater resistance to insects or diseases than
their parents.
7. Greater Adaptability. Hybrids are generally more adapted to
environmental changes than inbreds.
8. Faster Growth Rate.In some cases, hybrids show a faster growth
rate than their parents.

28. Hybrid Production
Hybrid variety are the first generation (F1) from crosses between two
purelines, inbreds or crosses between open pollinated varieties,
clones or other populations that are genetically dissimilar.
Hybrid variety were first commercialy exploited in maize.
Terminology related to
production of hybrid varieties.
Inbred
A nearly homozygous line obtained
through continuous inbreeding of a
cross- pollinated species with
selection accompanying inbreeding.
Top cross
Cross between an inbred line and
an open- pollinated variety
Test cross
Cross between F1 and homozygous
recessive parent
Single cross : A x B
Double cross:(A x B) x (C x D)
Three way cross : (A x B) x C
Variety cross :
A cross between two varieties

29. Procedure of Hybrid Production
1. Development of inbred lines: Pedigree method is generally practiced in the
development of inbreds. Inbred lines are developed by continues self fertilization
of a cross pollinated species. After each selfing desirable plants are selected and
self pollinated or sib pollinated. Usually it takes 6-7 generations to attain near
homozygosity.
2. Evaluation of inbreds : After an inbred line is developed, it is crossed with other
inbreds and its productiveness in single and double cross combination is
evaluated. Evaluation of inbreds may be divided into four steps
i. Phenotypic evaluation : It is based on the phenotypic performance of the inbreds
.Highly effective for characters with high heritability
ii. Top cross test: by Davis in 1927
iii. Single cross evaluation:
iv. Prediction of double cross performance. :
3. Production of hybrid seed
Requirement for hybrid seed production
1. Easy emasculation of the pollen parent
2. Effective pollen dispersal from the male parent
Emasculation
Either hand emasculation or male sterility are used for emasculation
Male sterility is economical for commercial production
Pollination
Artificial pollination is applied for better seed set

30. Merits
Exploit both GCA and SCA components of heterosis thus utilizing
heterosis to a greater extent
Produce from hybrid varieties is more uniform as compared to that of
open-pollinated, synthetic or composite varieties
Genetic composition of hybrids don`t change over time as they are
maintained in the form of parental inbreds
Demerits
Farmers have to use new hybrid seed every year
Hybrid production requires considerable technical skill which makes
it tedious and costly
Exploitation of full potential of hybrid varieties requires an adequate
and timely supply of inputs like irrigation, fertilizers, weed control, etc.
many farmers are unable to ensure timely application of these inputs.
In most cross- pollinated species, the requirements of isolation are
rigid and difficult to fulfill except on large farms
Achievements
Maize : DC : Ganga2
Bajra : SC: HB3, BJ 104, MBH 110

31. 7. Synthetic and composite breeding
The possibility of commercial utilization of synthetic
varieties in maize was first suggested by Hayes and
Garber in 1919. synthetic varieties have been of great
value in the breeding for those cross-pollinated crops where
pollination control is difficult.
DEFINITIONS
A synthetic variety is produced by crossing in all
combinations a number of lines that combine well with
each other. Once synthesized, a synthetic is maintained by
open pollination in isolation.
A composite variety is produced by mixing the seeds of
several phenotypically outstanding lines and encouraging
open-pollination to produce crosses in all combinations
among the mixed lines.

32. By definition, a synthetic variety consists of all possible crosses
among a number of lines that combine well with each other.
The lines that make up a synthetic variety may be inbred lines,
clones, open-pollinated varieties, short-term inbred lines or other
populations tested for GCA or for combining ability with each other.
The operations involved in the production of synthetic varieties are
briefly described below.
Evaluation of Lines for GCA
GCA of the lines to be used as the parents of synthetic varieties is
generally estimated by topcross or polycross test.
The lines are evaluated for GCA because synthetic varieties exploit
that portion of heterosis, which is produced by GCA.
Polycross refers to the progeny of a line produced by pollination
with a random sample pollen from a number of selected lines.
Polycross test is the most commonly used test in forage crops.
Polycross progeny are generally produced by open-pollination in
isolation among the selected lines. The lines that have high GCA are
selected as parents of a synthetic variety.
STEPS IN PRODUCING A SYNTHETIC VARIETY

33. Steps of A Synthetic variety
A synthetic variety may be produced in one of the following
two ways.
1. Equal amounts of seeds from the parental lines are mixed
and planted in isolation. Open-pollination is allowed and is
expected to produce crosses in all combinations. The seed
from this population is harvested in bulk; the population
raised from this seed is the Syn1 generation.
2. All possible crosses among the selected lines are made in
isolation. Equal amounts of seed from each cross is
composited to produce the synthetic variety. The population
derived from this composited seed is known as the syn1
generation.

35. MERITS OF SYNTHETIC VARIETIES
1. Synthetic varieties offer a feasible means of utilizing heterosis in
crop species where pollination control is difficult.
2. The farmer can use the grain produced from a synthetic variety
as seed to raise the next crop.
3. In variable environments, synthetics are likely to do better than
hybrid varieties. (wider genetic base of synthetic varieties ).
4. The cost of seed in the case of synthetic varieties is relatively
lower than that of hybrid varieties.
5. Seed production of hybrid varieties is a more skilled operation
than that of synthetic varieties.
6. Synthetic varieties are good reservoirs of genetic variability.

36. DEMERITS OF SYNTHETIC VARIETIES
1. The performance of synthetic varieties is usually
lower than that of the single or double cross
hybrids. This is because synthetics exploit only
GCA, while the hybrid varieties exploit both
GCA and SCA.
2. Synthetics can be produced and maintained only
in cross-pollinated crop species, while hybrid
varieties can be produced both in self- and cross-
pollinated crops.

37. Difference between synthetics and composites
Sr.
No.
Synthetics Composites
1 No. of inbredlines are less
(6-8)
No. of lines are more (even
upto 20)
2 GCA of parental lines is
tested
No. testing
3 Performance can be
predicted
Cannot be predicted
4 Broad based More broad based
5 Synthetic can be
reconstituted
Cannot be reconstituted at a
later date
6 Seed replacement after 4-5
years
After 3-4 years

38. In India, the first composite varieties were released in 1967;
The six maize composites were, Ambar, Jawahar, Kisan,
Vikaram, Sona and Vijay.
African tall – seven parent composit.
Synthetic : ICMV - 221
WCC - 75
Achievements

39. Population Improvement
This idea of population approach was first suggested by Palmer
in 1953.
Definition : Accumulation of desirable alleles in a population
through various breeding techniques is known as population
improvement and those breeding procedures that are used for
such work are referred to as population improvement approaches.
The population improvement methods may be grouped into two
general classes.
1. Selection without progeny testing : Plants are selected on the
basis of their phenotype, and no progeny test is carried out. Eg :
Mass selection.
2. Selection with progeny testing : The Plants are initially
selected on the basis of their phenotype, but the final selection of
the plants that contribute to the next generation is based on
progeny testing.

40. A. Selection a) Mass selection
It is the earliest method of selection.
Mass selection is example of selection
from a biologically variable population.
A number of plants are selected based on
their phenotype and open pollinated seed
from them are bulked together to raise the
next generation.

41. Procedure for evolving variety by mass selection
Original
population
First year
i. Large number of phenotypically similar plants
having desirable characters are selected.
ii. Seeds from selected plants are composited to raise
next generation.
Second year
i. Bulked seed from selected plant grow
ii. Mass selection may be repeated i.e. item from (i.)
and (ii.) from first year may be repeated.
Third year
X X X X X X
X X X X X X
X X X X X X
X X X X X X
X X X X X X
X X X X X X
X X X X X X
X X X X X X
i. Composited seed planted in a PYT along with
standard checks.
ii. Phenotypic characteristics of the variety are
critically examined and evaluated.
The variety is evaluated in coordinated yield trails at
several locations. It is evaluated in an initial
evaluation (IET) trail for one year. If found superior it
is promoted to main yield trails for 2 to 3 years.
Seed multiplied and released after giving a suitable name.
4th to 6th
year
7th year

42. Merits of Mass selection
Rapid and simple breeding method
Selection cycle is very short
Have high heritability
Effective in improving yield of cross pollinated
crops Demerits of mass selection
Phenotypic performance is greatly influenced by
environmental factors.
No control on the pollination
Inbreeding depression
Achievements
Cotton : Dharwad American Cotton
Bajra : Pusa moti, Baja puri, Jamnagar gaint, AF3,
ICMR 312 was developed at ICRISAT by mass
selection

43. Mass selection is used for improving a local variety.
 Large number of plants are selected (I year) .
 Individual plant progenies are raised (II year).
 Inferior, segregating progenies are rejected.
 Uniform progenies are selected and the seed is bulked.
 Preliminary yield trials are conducted in third year.
 Fourth to seventh year multilocation tests are conducted.
 Seed is multiplied in eight year and distributed in ninth
year.
b. Modification of mass selection

44. Many other modification are :
i. Detasseling
This is practiced in maize.
The inferior plants will be detasseled there by inferior pollen
from base population is eliminated.
ii. Panmixis
From the selected plants pollen will be collected and mixed
together. This will be used to pollinate the selected plants.
This ensures full control on pollen source.
iii. Stratified mass selection Unit selection
Here the field from which plants are to be selected will be
divided into smaller units or plots having 40 to 50 plants /
plot. From each plot equal number of plants will be selected.
The seeds from selected plants will be harvested and bulked
to raise the next generation, by dividing the field into smaller
plots, the environmental variation is minimized. This method
is followed to improve maize crop. It is also known as Grid
method of mass selection.

45. B. Progeny Testing and Selection
In this method initially plants are selected on the basis of
their phenotype, but the final selection of plant is based
on progeny test.
a. Half sib family selection:
Half sibs are those, which have one parent in common.
Here only superior progenies are planted and allowed to open
pollinate.
1. ear to row method
It is the simplest form of progeny selection. Which is extensively
used in maize.
This method was developed by Hopkins.

46. Half-sib selection
Individuals having one parent common are called as half sibs.
Source population
Select good looking plants
and intercross
Progeny test of selected
plants in isolation
A. Composite seed
from superior
progenies
B. Composite remnant
seed from plants with
superior progenies
1. season
2. season
3. season
Plants in each offspring
have female parent is
common. They are
half-sibs
They reveal combining
ability of selected plant

47. Source population
Superior plants selected
Composite open-pollinated Composite selfed
Half-sib
selection
with
testcross
Tester can
be more or
less
uniform

48. Original population
1st
year
2nd
year
3rd
year
May be repeated
One or more time
Yield trials
i. Plant selected on the basis of phenotype
ii. Open pollinated seed from each plant
harvested separately
i. Small progeny rows grown from the
selected plants
ii. Superior progenies identified and
selected
iii. Plants allowed to open pollination;
seed is harvested separetely
Same as in second year
First
selection
cycle
Second
selection
cycle
Third
selection
cycle
Ear to row

50. Merits of ear to row method
1. It is based on progeny test and not on the
phenotypes of individual plants, hence it is far ore
accurate reflection of the genotype than
phenotype
2. Inbreeding may be avoided if care is taken to
select a sufficiently large number of plant
progenies.
3. Selection scheme is relatively simple and easy.
Demerits
1. There is no control on pollination and plants are
allowed to open pollinate. Thus the selection is
based on the material parent only
2. The selection time is 2 year. Thus the time
required for selection is as much as in case of
mass selection.

51. Though this scheme in simple, there is no control over pollination
of selected plants. Inferior pollen may pollinate the plants in the
progeny row.
To over come this defect, the following method is suggested.
a. At the time of harvest of selected plants from base population
on single plant basis, part of the seed is reserved.
b. While raising progeny rows, after reserving part of the seeds, the
rest are sown in smaller progeny rows.
c. Study the performance of progenies in rows and identify the
best ones.
d. After identifying the best progenies, the reserve seeds of the best
progenies may be raised in progeny rows.
e. The progenies will be allowed for open pollination and best ones
are selected. There are number of other modifications made in the
ear to row selection.
For example,
i. The selected progenies may be selfed instead of open pollination
ii. The selected plants may be crossed to a tester parent. The tester
parent may be a open pollinated variety, or inbred
iii. The progeny test may be conducted in replicated trial.

52. Full sibs are those which are produced by mating
between selected plants in pairs. Here the progenies
will have a common ancestry. The crossed progenies
are tested. A x B B x A
Individuals having both parents common are known as full
sibs
They are derived from crossing of two plants from the same
population.
The crosses are made between selected pairs of plants in the
source population.
 Crossed seeds are used for progeny test and for
reconstituting the improved new base population
b. Full-sib selection

53. Composite remnant cross seed
from combinations with superior progenies
Full sib selection
based on
pair crosses
Measures specific
combining ability
between selected
plants
Source population
Cross pairs of selected plants

54. c.) Inbred or selfed family selection
Families produced by selfing.
S1 family selection
Families produced by one generation of selfing.
These are used for evaluation and superior
families are intermated (Simple recurrent
selection).
S2 family selection
Families obtained by two generations of
selfing and used for evaluation.Superior
families are intermated.

55. Select 50-100 plants phenotypically prior to
flowering from a population.
These selected plants are selfed to obtain S1
progenies which are evaluated in replicated trial in
the next season i.e. II season.
In the III season, remnant seeds from originally
selected plants (So) whose S1 progenies have
performed well, are composited and grown in
isolation to constitute a new base population in
which the 2nd cycle of S1 progeny test may be
started.
 S1 Progeny Test

56. Source population
self-pollinate selected plants
Composite remnant selfed seed
from selected plants with superior progenies
Selection from
S1 progeny
offspring test
Only if selfing
is possible

57. Merits of progeny testing and selection
Selection based on progeny test and not on
phenotype of individual plants.
Inbreeding can be avoided if care is taken
raising a larger population for selection.
Selection scheme is simple.
Demerits
No control over pollen source. Selection is
based only on maternal parent only.
Compared to mass selection, the cycle
requires 2-3 years which is time consuming.

58. This is one of the breeding methods followed for the
improvement of cross pollinated crop.
The recurrent selection was first suggested by Hayes and
Garber in 1919. Independently by East and Jones 1920.
In 1945, Hull coined term recurred selection.
Hull (1952) defined recurrent selection as “Method which
involves reselection generation after generation with
interbreeding of selects to provide for genetic
recombination”.
The main difference between progeny selection and
recurrent selection.
The manner in which progenies are obtained for
evaluation.
Instead of open pollination, making all possible inter
crosses among the selected lines.
Recurrent selection

59. Types of recurrent selections.
1. Simple recurrent selection
2. Recurrent selection for GCA
3. Recurrent selection for SCA
4. Reciprocal recurrent selection

60. Simple recurrent selection
Selection is based on phenotypic characters of
plants
Tester is not used in this scheme
It does not measure the combining ability
This method is useful only for those characters
which have high heritability.
Recurrent selection is effective in increasing the
frequency of desirable genes in the population
Most suited for characters having high heritability
Inbreeding is kept at minimum.
E.g.: oil content. Protein content and high
heritability traits are affective for increasing the
frequency of desirable genes in the selected
populations.

61. 1st YEAR
2nd YEAR
3rd YEAR
4 th YEAR
MAY BE REPEATED AS IN 1st CYCLE
Superior phenotypes are selfed.
Seeds are harvested .
Individual plant progenies are
planted. All possible intercrosses
are made and seeds are
composited.
Composited intercross seeds are
planted , selfing is done.
Individual plant progenies are
planted. All possible intercrosses
are made and seeds are
composited.
Original
Selection
cycle
1st
Recurrent
selection
cycle
STEPS IN BREEDING A VARIETY BY SIMPLE RECURRENT SELECTION

62. Recurrent selection for general combining ability was proposed by
Jenkins 1935.
The progenies are crossed with tester strain with a broad genetic
base. So plants are selected on the basis of superior performance of
their plant x tester progenies would have superior GCA.
A tester parent is a common parent mated to a number of lines.
Such a set of crosses is used to estimate the combining ability of the
selected lines.
A tester with broad genetic base means an open pollinated variety, a
synthetic variety or segregating generation of a multiple cross.
In this method selection is based on heterozygous tester cross
performance.
Recurrent selection for GCA can be used for two basically different
purposes.
1)It may be used to improve the yielding ability and the agronomic
characteristics of a population. In this case the end product will be a
synthetic variety.
2)It may be used to concentrate genes for superior GCA. Here the end
product will be superior inbreds. Such inbreds can be developed after
a few cycles of RSGCA
2. Recurrent selection for general combining ability

63. 1st Year
2nd Year
3rd Year
4th Year
5th Year
6th Year
MAY BE REPEATED AS IN 1st CYCLE
Original
Selection
cycle
1st
Recurrent
selection
cycle
SELF
POLLINATED
SEEDS
SELF
POLLINATED
SEEDS
TESTER
REPLICATED
YEILD TRAIL
TESTER
REPLICATED
YEILD TRAIL
INTER CROSS BLOCK
INTER CROSS BLOCK

64. The recurrent selection for SCA was first proposed by
Hull in 1945. the objective is the isolate from a
population such lines that will combine well with a
given inbred useful for selecting lines for SCA.
The procedure for recurrent selection for SCA is
identical with that of recurrent selection for GCA,
except that the tester used here is an inbred (narrow
genetic base) instead of open pollinated variety.
The objective of RSSCA is to isolate from population
such lines that will combine well with an inbred. These
lines are expected to give best hybrids in heterosis
breeding.
3. Recurrent selection for Specific Combining
Ability

65. Proposed by Comstock, Robinson, and Harvey (1949) to
select for both general and specific combining ability.
Improves both GCA and SCA of population for a character.
Basically two populations A and B are used. Each
serve as a tester for the other.
This method is used for genetic improvement of polygenic
characters.
A form of recurrent selection that is used to improve both
GCA and SCA of a population for a character using two
heterozyous testers is k/as Reciprocal Recurrent Selection
4. Reciprocal Recurrent Selection

66. 1st Year
2nd Year
3rd Year
TEST
CROSS
TEST
CROSS
SEPARATE FIELD TRAILS
SELFEDSEEDS
SELFEDSEEDS
Original
Selection
cycle
COMPOSITE SEESDS OF INTERCROSS ARE RAISED
AND FIRST RECURRENT CYCLE IS REPEATED

67. Use of RRS
•Two populations are developed by this
method
•They may be intermated to produce a
superior population with broad genetic base.
This is similar to a varietal cross but in this
case the populations have been subjected to
selection for combining ability (GCA and SCA)
•Inbreds may be developed from populations A
and B. These inbreds may be crossed to
produce a single cross or double cross
hybrids.

68. Case study 1.
Abstract
This paper reports the effects of three cycles of reciprocal recurrent
selection (RRS) on the means, genetic variances, and on the genetic
correlations for several traits in the IG-1 and IG-2 maize (Zea mays L.)
populations.
Interpopulation full-sib progenies from cycle zero (C0) and from cycle 3
(C3) of RRS were evaluated in two locations
objectives of the program: grain yield increased significantly, while plant
height and ear height decreased significantly. However, if the
magnitudes of the genetic variances continue to decrease, new sources
of improved germplasm should be incorporated into both populations to
allow the continued improvementof the interpopulation by RRS.

69. 20002000
IG -1 IG -21989-
90
1990-
91
Loc.1, 2 & 3 Loc.1, 2 & 3
1991-
92
C1
In both populations the lower ears were
selfed and the upper ears were crossed.
2000 (S1 & testcross plant) get from both
population.
2000 Testcross progeny evaluated at 3
location with 2 replication per location and
with 2 check.
200 progenies selected.
20 selfed seed progenies planted from both
population seperatly.
Intercross among IG 1 progenies. Seeds
from all intecross of IG 1 are mixed
together.
Two further cycles of RRS (C2 : 1992/1993 to 1994/1995; and C3 1995/1996 to
1997/1998) were carried out at the same locations using the same procedures.
1998-
99
400 plants
IG -2 IG -1
400 plants
X
After C3 cycle. IG-2 were used as females
and IG-1 used as male. 300 plants
pollinated. 200 progenies selected.

70. Table 1 - Mean values across environments of the interpopulation
(IG-1 x IG-2) from original (Cycle 0) and after three cycles (Cycle 3) of
reciprocal recurrent selection, and the responses to selection per cycle
in actual units and in percentage for several traits.
Traits IG 2 X IG 1 Response
per cycle
Response
per cycle
(%)Cycle 0 Cycle 3
Grain yield
(g plant-1)
116.68 ± 3.93 130.93 ± 3.68 4.75 4.07
Lodging
(plants ha-1)
6,930.55± 1,451.21 3,798.61 ± 937.75 -1,044.00 -15.06
Plant height
(cm plant-1)
215.33 ± 2.14 203.60 ± 2.23 -3.91 -1.81
Ear height
(cm plant-1)
123.69 ± 1.85 111.90 ± 1.69 -3.93 -3.17
Conclusion :
Grain yield increased significantly, while plant height, ear height,
and lodging decreased significantly.

71. Case study 2.
In the semi-arid zones of Uganda, pearl millet (Pennisetum
glaucum (L.) R. Br.) is mainly grown for food and income; but
rust (Puccinia substriata var indica (L.) R. Br.) is the main foliar
constraint lowering yield. The objective of the study was to
genetically improve grain yield and rust resistance of two
locally adapted populations (Lam and Omoda), through two
cycles of modified phenotypic S1 progeny recurrent selection.

72. Season Activity
First season
(February -
June 2012)
Growing 2000 plants for each population (C0 populations) and keeping
remnant seed Inoculation with rust urediniospores Selecting (S0) and selfing
500 plants (S1 progeny) showing low severity (10-20%) from each population
and bulking the seed
Second
season
(August -
November
2012)
Growing 2000 plants of each population and inoculating with rust
urediniospores Rogueing was done before flowering to leave 500 plants with
less than 20% rust severity for recombination. Bulking of selected C0 plants
was done to form C1 seed and remnant seed kept
First season
(February -
June 2013)
Growing 2000 plants from each of the two C1 populations Inoculation with
rust urediniospores Selecting and selfing 500 plants with less than 20%
rust severity to form S1 progeny
Second
season
(August -
November
2013)
Growing 2000 of S1 progeny from the C1 populations and inoculating with
rust urediniospores Rogueing before flowering to leave 500 plants with
less than 20% rust severity for recombination. Bulking seed to form C2 seed
First season
(February -
June 2014)
Evaluating the C0, C1, and C2 of each population in three rust hot spot
environments (Serere, Kitgum and Katakwi)
Table 2. Modified S1 recurrent selection scheme for pearl millet rust
resistance study in Uganda

73. Conclusion :
Significant net genetic gain for grain yield (72 and 36%) were achieved
in Lam and Omoda populations, respectively.
This led to grain yield of 1,047 from 611 kg ha-1 in Lam population
and 943 from 693 kg ha-1 in Omoda population.
Rust severity reduced from 30 to 14% in Lam population and from 57
to 17% in Omoda population.
Traits Lam Omoda
C2 C1 C0 C2 C1 C0
Grain
yield
1047.10 811.70 610.60 943.10 761.18 692.54
1000
grain
weight
9.14 5.95 5.44 10.70 10.89 9.87
Rust 13.45 16.83 29.89 16.76 23.99 56.77
Table 3. Means for selected traits of cycles for Lam and Omoda pearl millet
populations
GY = grain yield (kg plant-1), RUST = rust severity at 50% physiological
maturity, TGW = thousand grain weight (g)

74. Case study 3.
This study aimed to assess whether intra-population
selection and its derived lines inter-mating for grain iron
(Fe) has any associated changes in grain yield and other
agronomic traits in two Open-Pollinated Varieties (OPVs) in
pearl millet. The original (C0) and improved bulks (C1)
were evaluated in two contrast seasons (referred to as
environments). AIMP 92901 and ICMR 312,

75. Summer
2009
Initially, 300 S1’s were produced
rainy
season
2009
Selfed panicles were harvested and threshed, and
grain samples were analyzed for Fe and Zn
For S2 progeny plants in S1 rows are again selfed
2010
summer
Equal quantity of seeds from each of the 300 S1’s
were pooled and planted For recombination by
hand pollination (sib-mating) with bulk pollen
collected from 30 - 50 plants (within population)
and crossed on 15-20 plants of same population
on each day.
A total of 100-120 plants main panicles were
crossed with bulk pollen in each population.C0
2010
summer
Top 20 S2 progeny bulks were selected from each
population and for recombination using full diallel
mating design.
13 S2 progeny bulks from AIMP 92901 and 17 S2
progeny bulks from ICMR 312 were selected.13 17
C1
2010 Rainy
C0 C1 C0 C1
Harvested . Fe, Zn analysis.
Remnant S2 seed of selected progenies
bulked
AIMP
92901
ICMR
312
300
S1’s
300
S1’s

76. Cycle of selection Fe (mg kg-1) Zn (mg kg-1)
AIMP 92901
C0 68.3 46.3
C1 70.0 50.0
ICMR 312
C0 70.7 49.3
C1 76.3 52.0
Table 4. Mean performance of Fe and Zn density estimated after one cycle of
recurrent selection in two populations.
Conclusion
One cycle of recurrent selection showed marginal improvement for
grain Fe and Zn in C1 over C0 bulks of AIMP 92901 (2.4% more Fe
and 7.9% more Zn) and ICMR 312 (8% more Fe and 5.4% more Zn).
Nevertheless, these micronutrients are being additively controlled
so population improvement is possible with increased cycle of
selection and subsequent recombination to assemble more
favorable alleles for significant difference from its original bulks.

77. Conclusion
Various breeding methods that helpful to avoiding inbreeding
depression in cross pollinated crops.
The breeding methods help in accumulation of favourable allele in a
population.
Help in improvement of various traits.
Referances
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pearl millet (Pennisetum glaucum L.). American Journal of Experimental Agriculture 2(3):370-
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Govindaraj M., KN. Rai1 and P. Shanmugasundaram.2018. Reselection within population for
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