Bulk method pedigree method &line breeding

1. Bulk Method
Pedigree Method
&
Line Breeding
PRESENTED BY:
Pawan Nagar
Reg. no.: 04-2690-2015
M.Sc.(Fruit Science)

2. BULK METHOD
 The bulk method of breeding was first used by
Nilson – Ehle in 1908.
 This method is also known as “Mass Method”
or the “The Population Method”.
 Bulk population breeding is a strategy of crop
improvement in which the natural selection
effect is solicited more directly in the early
generations of the procedure by delaying
stringent artificial selection until later
generations.

3.  In the bulk method , F2 and subsequent
generations are harvested in mass or as bulks to raise
the next generation.
 At the end of bulking period , individual plants are
selected and evaluated in a similar manner as in
pedigree method.
 The duration of bulking may vary from 6-7 to 30 or
more generations.
 During bulking period, artificial selection may or
may not be practiced , but natural selection plays an
important role in shifting gene frequencies.
 When desirable purposes are fulfilled , bulking is
stopped and individual plants are selected and
evaluated.

5. ADVANTAGES
 Less record keeping than pedigree which saves
time & labour.
 Very simple, convenient & less expensive.
 Natural selection increases the frequency of
superior genotypes in the population.
 More useful than pedigree method with lower h2
traits
 There is greater chance for isolation of
transgressive segregates than in pedigree method
due to large population.
 Most suitable for improvement of small grains.

6. DISADVANTAGES
1.Environmental changes from season to season so adaptive
advantages shift
2. It takes much longer time to develop a new variety.
3. Not useful in selecting plant types at a competitive
disadvantage (dwarf types)
4.Final genotypes may be able to withstand environmental
stress, but may not be highest yielding
5. If used with a cross pollinated species, inbreeding
depression may be a problem
6. It provides little opportunity for breeder to exercise his skill
or judgement in selection.

7. APPLICATIONS
 The bulk method is suitable for handling the
segregating generations of cereals, small millets,
grain legumes and oilseeds. It may be for
different purposes like :-
1) Isolation of homozygous lines with a
minimum efforts and expenses.
2) Waiting for the opportunity for selection ,
natural /suitable environmental condition.
3) To provide opportunity for natural selection
to change the composition of the population.

8. PEDIGREE METHOD
 The method was first described by H. H. Lowe in
1927.
 Pedigree : “A description of the ancestors of an
individual and it generally goes back to some
back to some distant ancestors in the past”
 Thus, a pedigree would describe the parents ,
grand parents , great grand parents and so on.
 The pedigree is helpful in finding out if two
individuals are related by descent their
ancestry, and therefore, are likely to have some
genes in common.

9. PEDIGREE RECORD
 In pedigree method, a detailed record of the
relationships between the selected plants and
their progenies is maintained.
 As a result, each progeny in every generation
can be traced back to the F2 plants from which
it is originated such a record is known as
Pedigree- Record.

10. PROCEDURES
 In pedigree method, individual plants are
selected from F2 and the subsequent
generations, and their progenies are tested.
 During the entire operation a pedigree
record is kept.
 Individual plant selection is continued till
the progenies show no segregation. At this
stage , selection is done among the progenies
because there would be no genetic variation
within the progenies.

12. ADVANTAGES
1. Record keeping provides a catalog of genetic
information of the cultivar.
2. Selection is based not only on phenotype but
also on genotype (progeny row).
3. Using the records, the breeder is able to
advance only the progeny lines in which
plants that carry the genes for the target traits
occur.
4. A high degree of genetic purity is produced in
the cultivar.
5. The breeding value of value of selected
plants is ascertained by progeny test.

13. DISADVANTAGES
1. Record keeping is slow, tedious, time-
consuming, and expensive.
2. The method is not suitable for species in which
individual plants are difficult to isolate and
characterize.
3. Pedigree selection is a long procedure, requiring
about 10–12 years or more to complete, if only
one growing season is possible.
4. Since large number of progenies are rejected in
this method, there are chances of elimination of
some valuable material.

14. APPLICATIONS
 For the improvement of self pollinated species
for the development of new pure line varieties.
 This method is also used in cross pollinated
species for the development of inbred lines.
 Used for polygenic traits than oligogenic.
 It is used to correct some specific weakness of
an established variety with aims to improve the
yield and quality parameters.
 It is also useful in the selection of new superior
recombinants from segregating population.

15. ACHIEVEMENTS
Crop Examples
Rice Krishna,Sarbarmati,Ratna,Padma,Jaya,Bala,Kaveri
Wheat HD 2281, HD2285,HD2380, ND 2402 , Janak , Pratp,
Raj 2535
Cotton LH 900, LH 1556, F 846, F 1054, F 1378, HS 6, Vikas,
Sharda , MCU 9, MCU 11, LRA 5166
Pigeon pea T 21, Prabhat
Green gram T2, T 44 , T51, Sheela
Chickpea T1, T2, T3, T5 , Radhey
Pea Pant Matar 2, Jawahar Matar 1, Jawakar Matar 4

16. Pedigree Method Bulk Method
1 Most widely used Breeding
method
Used only to a limited extent
2 Individual plants are selected
in F2 & subsequent
generations and individual
plant progenies are grown
F2 and subsequent generations are
grown in bulk
3 Artificial selection ; artificial
disease epidemics etc. are an
integral part of the method
Mainly natural selection. In certain
cases artificial selection may be
essential
4 Pedigree Records have to be
maintained which is often time
consuming &laborious
No pedigree records are maintained
5 Generally its taken 12-13
years to release new variety
Takes more than 15 years.
6 Requires close attention of
breeder from F2 onwards
It is quite simple and does not
require much attention

17. LINE BREEDING
 Three types of line Breeding Approaches in
Line Breeding
1. One Line Approach
2. Two Line Approach
3. Three Line Approach

18. ONE LINE BREEDING - APOMIXIS
 Apomictic lines are those lines which are developed
without means of sexual reproduction and they have
different component ways in producing like
parthenogenesis, apogamy, apospory,and adventive
embryony .
 Since these lines are capable of maintaining genetic
purity over generations there is high regard for these to
produce hybrid.
 Apomixis is effective means for rapid production of
pure lines

19. APOMIXIS
 Haploid parthenogenesis give rise to haploid plants
which upon colichine treatment will produce diploid
pure lines that can be used in plant breeding
programmes.
 A superior plant type which produce seed by apomictic
means will usually bread true for the characteristics of
mother plant
 Thus apomixis is useful in maintaining the
characteristics of mother plant from generation to
generation.

20. TWO LINE BREEDING
Two line
Approach
Cytoplasmic
Male
Sterility
Genetic
Male
Sterility

21. GENETIC MALE STERILITY
 The male sterile line (ms ms ) is allowed to be
cross pollinated with a male fertile (Ms Ms )
that combines well with the male sterile line,
the seed produced on the male sterile line is the
hybrid seed, the hybrid is male fertile (Ms ms )
 It commercially exploited in castor and pigeon
pea.
 GMS presents a serious problem , in the female
parent , 50 % is male fertile which is identified
and eliminated before they shed pollen.

22. THIS PROBLEM IS OVERCOME BY PHOTOPERIOD SENSITIVE OR
TEMPERATURE SENSITIVE GENETIC MALE STERILITY . HOW IT IS
WORKS IS SHOWN UNDER.

23. CYTOPLASMIC MALE STERILITY
 This type of male sterility is determined by the cytoplasm.
 Since the cytoplasm of a zygote comes primarily from egg
cell, the progeny of such male sterile plants would always be
male sterile.
 Nuclear genotype of male sterile line would be almost
identical to that of the recurrent pollinator strain.
 The male sterile line is maintained by crossing it with the
pollinator strain used as the recurrent parent in the
backcross programme since its nuclear genotype is identical
with that of this new male sterile line.
 such a male fertile line is known as the maintainer line or B
line as it is used to maintain the male sterile line is also
known as the A line

24.  Cytoplasmic male sterility may be utilized for
producing hybrid seed in certain ornamental
species, or in species where a vegetative part is
of economic value.
 But in those crop plants where seed is the
economic part, it is of no use because the hybrid
progeny would be male sterile.
 Cytoplasmic male sterility is not influenced by
environmental factors such as low or high
temp.,in other words the sterility is stable.

25. THREE LINE BREEDING -- CGMS
 This is a case of cytoplasmic male sterility where a
nuclear gene for restoring fertility in MS line is known.
 This system involves
1. Cytoplasmically determined MS plants known as A line
in the genetic constitution.
2. Fertile counter parts of A line known as maintainer line
or B line with the genetic constitution.
3. Restorer plants used to restorer the fertility in
commercial seed plots known as R lines in the genetic
constitution.

26. Maintenance of Male Sterile Line or A line:
Since A line does not produce pollen, seed is not formed for
maintaining A line. It has to be crossed with its fertile
counter part having similar nuclear genes with fertile
cytoplasm which is known as B-line.
Production of Hybrid seed:
• For production of hybrid seed, A-line has to be kept as
female parent and the pollen parent should posses the
restorer genes in order to induce fertility and seed
development in the next generation.
• Such line is known as restorer line and denoted as ‘R’ line.
• The A line & R line should be of different genetic
constitution and should be able to give maximum
heterosis.

28. LIMITATIONS IN USING MALE STERILE
SYSTEMS:
1. Existence and maintenance of A, B & R Lines is
laborious and difficult
2. If exotic lines are not suitable to our conditions, the
native/adaptive lines have to be converted into MS lines
3. Adequate cross pollination should be there between A
and R lines for good seed set.
4. Synchronization of flowering should be there between
A & R lines.
5.Fertility restoration should be complete otherwise the F1
seed will be sterile Isolation is needed for maintenance
of parental lines and for producing hybrid seed.