Methods of crop improvement and its application in crosspollinated crops

Different Breeding methods for crop improvement in the cross pollinated crops.

1. DOCTORAL SEMINAR
ON
METHODS AND APPLICATIONS OF
POPULATION IMPROVEMENT
Presented by
Biswajit Sahoo
Ph.D. 1
st
year
DEPARTMENT OF GENETICS AND PLANT BREEDING
COA, RAIPUR, (C.G.)

2. INTRODUCTION
Population improvement was the earliest method applied to cross-
pollinated crops.
It deals with the improvement of crops and production of new crop
varieties which are far superior to existing types in all characters.
The result of improvement leads to higher yield, agronomically more
stable, resistant to diseases, insects, drought, frost, floods, alkaline and
saline conditions, improve the quality of produce such as size, colour,
shape, taste, nutritional value.
Different breeding methods are being used in different crops to improve
the genotype of crop based on their mode of pollination.

3. BASED ON THE MODE OF POLLINATION CROPS ARE CLASSIFIED INTO


Mode of pollination Example
Self pollination Rice, Wheat, Barley, Oats, Chickpea, Pea, Cowpea, Lentil,
Greengram, Blackgram, Soybean, Linseed, Brinjal,
Tomato, sesame, khesari, Sunhemp, Chillies, Okra,
Peanut, Mothbean, Common bean
Cross pollination Corn, Pearlmillets, Rye, Lucern, Radish, Cabbage,
Sunflower, Sugarbeet, Castor, Rape Seed, Safflower,
Spinach, Onion, Garlic, Turnip, Musk melon, watermelon,
Carrot, Coconut, Papaya
Often cross
pollination
Sorghum, Cotton, Triticale, Rai, Pigeonpea, Tobbaco, Jute
Vegetatively
propagated
Sugarcane, Coffee, Cocoa, Tea, Apple, Pears, peaches,
Cherries, Grapes, Almond, Pineapple, Banana, Cashew,
Strawberry, Mango, Cassava, Taro, Rubber, Sweet Potato
Source: Book: objective science of plant breeding by Phundan Singh

4. BREEDING METHODS FOLLOWED BASED ON MODE OF
POLLINATION
Self pollinated crops Cross pollinated crops Vegetatively propagated
crops
Plant Introduction Plant Introduction Plant Introduction
Mass selection Mass selection Clonal Selection
Pure line selection Recurrent Selection Mass selection
Pedigree method Synthetics Heterosis Breeding
Bulk method Composites Mutation Breeding
Single seed descent method Back cross method Polyploidy Breeding
Back cross method Heterosis Breeding Distant hybridization
Heterosis Breeding Polyploidy Breeding Transgenic Breeding
Mutation Breeding Distant hybridization
Polyploidy Breeding Transgenic Breeding
Distant hybridization
Transgenic Breeding

5. TT
TT
TT TT TT TT TT TT TT TT
TT TT TT TT TT TT TT TT
Tt Tt Tt Tt Tt Tt Tt Tt
Tt Tt Tt Tt Tt Tt Tt Tt
TT
TT TT TT TT TT TT TT
TT TT TT TT TT TT Tt Tt Tt Tt Tt Tt Tt
Tt Tt Tt Tt Tt Tt Tt
Homozygous and Homogenous
Homozygous and Heterogeneous
Heterozygous and Homogeneous
Heterozygous and Heterogeneous
Different types of genetic populations in plant
breeding

6. DIFFERENT TYPES OF GENETIC POPULATIONS IN
PLANT BREEDING
Population Brief Description Examples
Homozygous Non-segregating populations Pure lines, inbred lines, mass selected
autogamous varieties and multilines
Heterozygous Populations segregate on selfing F
1
hybrids, composites, synthetics and
a clone
Homogeneous

Genetically similar population Pure lines, inbred lines, F
1
hybrids
progeny of a clone
Heterogeneous Genetically dissimilar population Land races, composites, synthetics and
multilines
Combinations
Homozygous and
Homogeneous
Genetically similar and non-
segregating population
Pure lines and inbred lines
Heterozygous and
Homogeneous
Genetically similar but
segregating on selfing
F
1
hybrids between inbred lines and
progeny of clone
Homozygous and
Heterogeneous
Genetically dissimilar but non-
segregating populations
Multilines and mass selected varieties
in autogamous species
Heterozygous and
Heterogeneous
Genetically dissimilar but
segregating populations
Composites and synthetics

7. CHARACTERISTICS OF CROSS POLLINATED CROPS

Each genotype has equal chance of mating with all other
genotypes.

Individuals are heterozygous in nature.

Higher degree of inbreeding depression.

Wide adaptability and more flexibility to environmental changes
due to heterozygosity and heterogenity.

Cross pollination permits new gene combinations from different
sources.

Individuals have deleterious recessive gene which are concealed by
masking effect of dominant genes.

8. FOCUS OF BREEDING CP CROPS
Population Improvement
 Heterozygosity
 Quantitative Traits/Characters
 To pre-dominate a desirable genotype in
population
 Arising new genotypes (gene recombination)

10. A BRIEF DESCRIPTION OF VARIOUS SELECTION SCHEMES FOR
POPULATION IMPROVEMENT
Selection scheme Brief description
Intra-population improvement For improvement within a population
A. Mass selection Selection based on phenotype of individual plants;
selected plants reproduce by open-pollination.
1. For one sex Inferior plants present in the population are detasselled;
open-pollination among the remaining plants.
2. For both sexes All plants in the population allowed to produce pollen;
open-pollination without any restriction.
3. Stratified Field divided into small plots of about 40 plants each;
selection within small plots; open-pollination without any
restriction; selection usually for one sex only.
4. Constiguous control Plants of a single genotype (single cross, inbred) used as
check and planted after every 2-4 hills for comparison;
check plants detasselled; other plants open-pollinate;
selection usually for one sex.

11. B. Family selection Selection based on means of individual plants progenies or
families.
1. Half-sib Plants within each family (individual plant progeny) half-sibs,
i.e. have one parent (usually the female) in common.
a. Ear-to-row families produce by open-pollination; selection within superior
families; no replicated trial; unrestricted open-pollination
among all the families
b. Modified ear-
to-row
As in ear-to-row; superior progenies identified by replicated
yield trial; pollen source: a random bulk of all the families
c. Half-sib
selection
As in the modified ear-to-row, but only superior progenies
planted in the crossing block and allowed to open-pollinate
d. Modified half-
sib
Half-sibs used for yield trial; S
1 families from plants producing
superior half-sibs intermated through open-pollination
e. Broad base
test cross
Hail-sib families produced by crossing the selected plants to a
tester with a broad genetic base (parental or unrelated) used
for yield trial; S
1 progenies from plants producing superior
half-sib families intermated (syn., recurrent selection for GCA)
f. Narrow based
test cross
As in the broad base testcross, but the tester has a narrow
genetic base (syn., recurrent selection for SCA)

12. 2. Full-sib Plants within each family are full-sibs; produce by mating the selected
plants in pairs.
a. full-sibs
intermated
Full-sibs used for yield trial; superior full-sibs intermated

b. S
1 progenies
intermated
Full-sibs used for yield trial; S
1 progenies from the plants producing
superior full-sibs intermated
3. Inbreds or selfed Families produced by selfing
a. S
1 Families produced by one generation of selfing used for evaluation;
superior families intermated (syn., simple recurrent selection)
b. S
2 Families produced by two generation of selfing used for evaluation;
superior families intermated
Inter-population
improvement
Two populations improved simultaneously for combining ability with
each other
A. Half-sib reciprocal
recurrent selection(HS-
RRS)
Reciprocal with half-sib progeny.
B. Full-sib reciprocal
recurrent selection (FS-
RRS)

Each selected plant in the population A and is selfed. Each selected
plant from A is test crossed with one selected plant from B. The test
cross progenies are evaluated in field trial. S
1 families of plants from
A producing superior test cross progenies are intermated; the same is
done from B. Requires at least two ears/plant in one of the two
populations.

14. MERITS



1.Selection is extreme simple and rapid.
2.Selection cycle is very short and only one generation.
3.Highly efficient to improve easily identifiable and high heritability characters like e.g.
plant height, size of the ear, date of maturity.
4.With proper care it effective to improve yield as well.
5.Most CP crops have a high additive component of genetic variance, which respond to
selection.
6.Extensive yield trials are not required as improved strain is likely similar to original
population.
Demerits
1.Selection based on the superiority is poor basis of selection
2.Both superior and inferior plants present because of open-pollination, so reduces the
effectiveness of selection.
3.High selection intensity reduces population size, leads to inbreeding depression.

15. STRATIFIED MASS SELECTION
Suggested by Gardner in 1961.
Also known as grid method of mass selection
Entire field is divided into small plots, each
having 40-50 plants.
Superior plants are selected in each small plot.
Seeds are selected and composited to raise the
next generation.

16. CASE STUDY ON MASS SELECTION

17. ACHIEVEMENTS
Crop Variety
Pearlmillets Babapuri, Jamnagar giant, AF3, S530, Pusa
moti ( all from african introduction)
Rai (Brassica juncea) Type 11, L16
toria Abohar
Yellow sarso (B. campestris var. yellow
sarso)
T42, T16
Brown sarso (B. campestris var. brown
sarso)
17 dwarf, 17 medium, DS1, DS2
Maize T41, T19, Jaunpuri
Cotton Desi cotton (G. arboreum): C402, C520,
C1281, K12
American cotton (G. hirsutum): 100F, 216F,
A19

Castor (Ricinus communis) S20, B1, B4
source: Seednet.com

20. CASE STUDY OF MODIFIED EAR TO ROW METHOD

21. Merits of progeny selection
It is more dependable reflection of genotypic worth of the selected plants than
their phenotype.
It is more efficient improving yield ability of opv of maize
Avoid inbreeding depression if sufficient large amount of progenies are taken
and if the selected plants are not closely related.
Relatively simple and easy, but some modifications are complicated and tedious.

Demerits of progeny selection
Most progeny selection allowed to open-pollinate, so selection is based on
maternal parent only, which reduces the efficiency of the selection
Schemes are complicated and involve considerable work.
Selection cycle usually two year, i.e. each selection cycle takes twice as much as
mass selection.

22. RECURRENT SELECTION
It is defined as reselection generation after generation with
inbreeding of selects to provide for genetic recombination (Hull,
1945).
To increase frequency of favourable gene for quantitative
character/trait.
Identification of genotype superior for the specific quantitative
character being improved.
Subsequent intermating of superior genotypes to obtain new gene
combination.
Cycle may be repeated as long as superior genotypes possessing
gene for character of interest are generated.

24. phenotypic Recurrent Selection
To improve plant’s quantitative characters based on visual observations,
physical measurement of character.
E.g. Oil content in corn and fibre strength in cotton.
Genotypic Recurrent Selection
Its the selection to improve a plant quantitative character based
on progeny performance as measured by test crosses, or by other
means, and is utilized to improve complex characters such as
combining ability in corn inbred lines

25. Model for phenotypic recurrent selection
90
120
140
140
120
135
120
130
140

27. RECURRENT SELECTION FOR GCA

28. CASE STUDY ON RSGCA

29. RECURRENT SELECTION FOR SCA

30. CASE STUDY OF RSSCA

31. COMPARISON
Particular Recurrent selection for
GCA
Recurrent selection for
SCA
Application Used to increase polygenic
traits
Also used to increase
polygenic traits
Basis of selection Test cross performance Test cross performance
Tester used Heterozygous Homozygous
Effectiveness Incomplete dominance Complete and Over-
dominance
Condition of use Used when additive gene
action important
Non- additive gene action
important
Impact Used to improve GCA
characters
Improve SCA characters

32. RECIPROCAL RECURRENT SELECTION

33. CASE STUDY OF RRS

34. MERITS OF RECURRENT SELECTION METHODS
Efficient method to increase the frequency of the superior genes in a
population.
It helps in maintaining the high genetic variablility in a population
due to repeated intermating of heterozygous population.
The selection is based on the test cross performance and only
selected plants are allowed for inter-mating.

deMerits of recurrent selection methods
Involves lots of selection, crossing and selfing work.
Permits selfing which leads to loss of genetic variability.
It is not directly used for the development of new varieties.

35. COMPARISON AMONG DIFFERENT RECURRENT
SELECTION SCHEMES
1.When dominance is incomplete, RRS and RSGCA would be comparable in
their effectiveness, and both will be superior to RSSCA.
2.When dominance is complete, the three methods would be equally
effective.
3.When dominance is over-dominance, RRS and RSSCA would be equally
effective, but both would be more effective than RSGCA.
4.The above relationships are expected when there epistasis, multiple alleles
and linkage disequilibrium are absent.
5.In most crop species epistasis is important and linkage disequilibrium and
multiple alleles are likely to be present. In such cases, RRS would be
superior to RSGCA and RSSCA.
6.In all practical situations, RRS would be superior to RSGCA and RSSCA.

36. FULL-SIB SELECTION
1.With full-sib selection, crosses are made between selected pairs of plants
in the source population, with the crossed seed used for progeny tests and
for reconstituting the new population.
2.First season
Cross 150 to 200 pairs of plants selected from the source population.
Reciprocal crosses may be made to provide a larger quantity of crossed
seed.
3. Second season
Grow a replicated progeny test with seed from each pair of crosses
keeping the remnant crossed seed.
4. Third season
Reconstitute the source population by mixing equal quantities of
remnant crossed seed from 15 to 20 paired crosses with superior
progeny performance, and grow in isolation with open pollination to
obtain new gene combinations.

37. FULL-SIB SELECTION METHOD

38. SELECTION FROM S
1 PROGENY TEST
1.S
1 refers to the progeny following self pollination of plants in
an open pollinated population, or in the F
2 following a cross.
2.First season
 Select 50 to 100 plants from a source nursery prior to
flowering.
 Self pollinate and harvest selfed seed from selected S
0 plants.
3. Second season
 Grow replicated S
1 progeny trial, keeping remnant seed (S
0)
seed.
4. Third season
 Composite equal quantities of remnant seed from the So
plants with superior progenies, and grow the seed
composite in isolation to obtain new gene combinations.

39. SELECTION FROM S
1 PROGENY TEST

40. SYNTHETIC VARIETIES
A variety produced by crossing in all combinations a number
of lines that combine well with each other is known as a
synthetic variety.
It is maintained by open pollination in isolation.
The lines may be inbreds, clones, and OPV.
The end product of recurrent selection, which are already
tested for GCA are generally, used to constitute synthetic
varieties.
5-8 good GCA inbreds are used for synthetic Variety.

42. CASE STUDY ON SYNTHETIC VARIETY

43. ACHIEVEMENTS OF SYNTHETICS
Crop Variety
Sugarbeet Pant synthetic-3
Bajra Synthetic- 3
Cauliflower ICMS-7703
Maize Varun (Synthetic B-41)
Source: seednet.com

44. COMPOSITES
Mixing the seeds of several phenotypically outstanding lines
produces a composite variety.
Outstanding lines may be germplasm inbreds, varieties,
hybrids, advance generation lines.
Rarely tested for general combining ability.
Maintained by open pollination in isolation.
Farmers can use their own seed for 3 ton 4 years.

45. PROCEDURE



Select Lines producing desirable characters
(selected lines should be like earliness, insect resistance, drought and frost resistance)

Seeds of desirable characters mix together

Random mating for 4-5 generations

Uniform populations are tested in replicated trials
High yielding stable type can be released as variety

46. ACHIEVEMENTS OF COMPOSITES
Crop Variety
Maize Amber, Jawahar, Kissan, Vikram, Sona,
Vijay, Co-1, NLD, Renuka, Kanchan, Diara-3,
Bajaura Makka, Pant Sankul Makka 3,
Chandramani, Pratap Kanchan 2, Pratap
Makka 5, Pusa Composite 3, Pusa
composite 4.
Maize (Opaque-2) Shakti, Rattan, Protina, Shakti 1, VL Babay
Corn 1, VL 78 and CoBC 1
Bajra WCC-75, RCBIC-9, ICPT-8203
Toria Composite I
Source: seednet.com

48. CONCLUSION
The improved population resulting from
various schemes are excellent sources of
good inbred lines, such populations may
be expected to become increasingly
important in the future.

49. QUESTION
Is recurrent selections applicable to self
pollinated crop or not, justify your
answer ?

50. THANK YOU………..
FOR YOUR KIND ATTENTION