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Breeding methods in cross pollinated crops
1. BREEDING METHODS IN CROSS
POLLINATED CROPS
Deva Ram
E-mail-mail2devhingra@gmail.com
DEPARTMENT OF GENETICS AND PLANT BREEDING
ALLAHABAD SCHOOL OF AGRICULTURE
SAM HIGGINBOTTOM INSTITUTE OF AGRICULTURE, TECHNOLOGY AND
SCIENCES
3. Breeding methods in cross pollinated crops
Breeding methods
|
Population improvement Hybrid and
Synthetic
varieties
(Used to increase the (A variable no. of
frequency of desirable strains are crossed
alleles) to produced a hybrid
population)
4. Breeding methods in cross pollinated crops
Methods of population improvement
Breeding methods Breeding methods with
without progeny progeny test
Test
Eg:-(Mass selection) (Progeny test, Ear to
row method and
Recurrent selection)
5. Methods with cross-pollinating crops
Intrapopulation improvement
1. Mass selection
2. Modified mass selection
3. Ear to row method
4. Modified ear to row method
5. Half sib selection
6. Modified half sib selection
7. Full sib selection
8. Recurrent selection
recurrent selection for sca
recurrent selection for gca
8. Mass Selection
Selection of individuals
Sampling seed of selected
individuals to plant next
generation
Oldest method of crop
improvement
Improvement of
heterogeneous native
populations or landraces
9. Mass selection
Mass Selection
same form as with self-pollinated crops
essentially a form of maternal selection since no
pollination control
select desirable plants
bulk seed
repeat cycle
with strict selection breeder will reduce population size
slow genetic gain since lack pollination control
must be able to ID superior phenotypes
Not suitable for quantitative traits
10. MASS SELECTION
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Grow population
Allow random mating
Harvest and bulk seed
from desirable plants
Plant new generation
Repeat
(Source: Tinker, 2008)
11. Mass Selection
Higher percentage of desirable genotypes
Method can only be used in environments where
trait is expressed - may not be suitable for off-
season winter nurseries
Effectiveness is function of heritability
Manage field to enhance differences: eg. irrigate
excessively to increase disease pressure
12. Mass Selection
Achievements :-
Early varieties of bajra - Babapuri, Jamnagar giant, Pusa moti.
Toria – increase the yielding ability by 30% and oil 56%, in Abohar.
Rai – many early, erect to semierect types developed, Type- 11.
Yellow sarson – T-42, T-16.
Brown sarson – 17 dwarf, 17 medium, DS-1, DS-2.
Maize – T-41, 19, Jaunpuri.
Desi cotton – C-402, C-520.
American cotton – 100F, 216F
castor – B-1, B-4.
14. Modified mass selection
Also known as stratified mass selection or grid method of
mass selection.
This modification is suggested by Gardner in 1961.
Field is divided into several small plots, eg., having 40-50
plants each.
Selection is done within the plots and not among the plots.
Seeds are selected and composite to raise the next
generation.
18. Modified ear-to-row method
1. First year. Plants selected on the basis of phenotype.
open pollinated seed from each plant harvested
separately.
2. Second year. Small progeny rows are grown and
evaluated. The remaining seed from the plants producing
superior progenies bulked to raise the next generation.
3. Third year. The bulked seed of 2 year planted and
allowed to open pollinate. Plants with superior phenotype
selected and seed harvested separately. The selection
cycle may be repeated one or more times.
19. Modified ear-to-row method
This modification of ear to row method was
widely used in breeding of maize in U.S.A.
and was responsible for the development of
several varieties.
21. Recurrent Selection
designed to increase the freq. of desirable genes
within a population
developed in the 1940s for developing inbred
lines
first suggested by Hayes and Garber in 1919
and independently by East and Jones in 1920.
22. Recurrent Selection
The schemes are divided into following four types:-
1. Simple recurrent selection
2. Recurrent selection for gca
3. Recurrent selection for sca
4. Reciprocal recurrent selection
25. Reciprocal Recurrent Selection
Proposed by Comstock, Robinson, and Harvey
(1949) to select for both general and specific
combining ability
General combining ability (GCA) is the ability
of a breeding strain to combine favorably with
many other strains or inbred lines. Analogous to
ADDITIVE gene action
Specific combining ability (SCA) is the ability
of a genotype to combine favorably with one or
a few other genotypes. Analogous to
DOMINANT gene action
27. Reciprocal Recurrent Selection
Proposed by Comstock, Robinson, and Harvey
(1949) to select for both general and specific
combining ability
General combining ability (GCA) is the ability
of a breeding strain to combine favorably with
many other strains or inbred lines. Analogous to
ADDITIVE gene action
Specific combining ability (SCA) is the ability
of a genotype to combine favorably with one or
a few other genotypes. Analogous to
DOMINANT gene action
28. Reciprocal Recurrent Selection
Although Recurrent and Reciprocal Recurrent
Selection methods were originally designed and
used to improve the chances of developing superior
inbreds of corn, these procedures are not used
explicitly in private industry for that purpose today.
Most new inbreds in sorghum are developed
through pedigree or pedigree type procedures and
in corn doubled haploids procedure have become
popular since about 2000.
30. Hybrid Production
Production of heterozygous populations from
the crossing of homozygous lines
Mostly used for cross-pollinated crops
The hybrid seed must be reproduced each year
The word HYBRID denotes a population of F1
plants derived by crossing inbred lines, clones,
open-pollinated varieties or any population that
are genetically dissimilar.
31. Hybrid Production
Steps involved
Produce inbred lines
Cross the inbred lines
Single cross hybrid
Harvest the female rows because they have the hybrid
seed
Double cross hybrid
Three way cross hybrid
33. Hybrid Production
Achievements:-
First hybrid varieties in maize were released in 1961, viz.,
Ganga-1, Ganga-101, Ranjit & Deccan
First hybrid bajra was developed by PAU. Ludhiana in 1965
as HB-1. Subsequently, HB-3 & HB-5 were released.
Bajra – PHB-10, PHB-11, BJ-104 & BK-560.
34. Weaknesses
Many years to provide a commercially
marketable seed.
Crossing can only occur within the same
species, and often selection is inefficient
because it depends primarily on phenotypes.
Finding the desirable trait takes large numbers
of crosses so space can be a premium.
36. Synthetic varieties
Steps involved in the production of synthetic
varieties:-
Step-1 Evalulation of lines for gca
Topcross or polycross test for gca; outstanding lines
selected as parents.
Step-2 Production of the synthetic
Method 1. Equal seed from all the lines mixed and planted in
isolation. Open-pollinated seed harvested as the synthetic
variety(syn1)
37. Synthetic varieties
Method 2. The parental lines are planted in a crossing block.
All possible intercrosses are made. Equal seed from all the
crosses mixed to produced the synthetic variety (syn1).
Step-3 Seed multiplication
Seed of the synthetic variety may be multiplied for one or
two generations before distribution.
Open pollination in isolation (syn2 or syn3).
38. Synthetic varieties
Achievements:-
Widely used in forage crops.
Synthetic varieties have been developed in maize,
pearlmillet, sunflower, sugarbeet, alfalfa, lucerne and
several other crops in USA.
In India, synthetic varieties have been developed in
pearlmillet at ICRISAT and in sugarbeet at Pantnagar
university.
Sugarbeet – Pant synthetic-3
Cauliflower – synthetic-3