This document provides information on various plant breeding methods. It discusses the production of new crop varieties through selection, introduction, hybridization, ploidy, mutation, and tissue culture. Popular plant breeders like M.S. Swaminathan and Venkataramanan are mentioned. Introduction of plants from their native places to new locations for crop improvement is described. Breeding methods like inbreeding, outbreeding, and heterosis are explained. The theories of heterosis like dominance hypothesis and overdominance hypothesis are presented. The document highlights the effects and advantages of hybrid vigor in crops.

1. PLANT BREEDING METHODS
SUBMITED BY,
M. THILAKAR,
LS1154
SECOND YEAR.
M.SC IN LIFE SCIENCES,
BHARATHIDASAN UNIVERSITY,
TIRUCHIRAPALLI.

2. Plant Breeding
 The Production of New crop varieties which are
Superior to their Parents.
 New crop are evolved by means of Selection,
Introduction,
Hybridization, Ploidy, Mutation, Tissue culture.

3. Popular scientists in Plant
breeding
M S SWANI NAATHAN VENKATARAMANAN

4. Introduction of Plants
 Process plants introduced from their Native place
to Another place
for Crop Improvement.
A). INTRODUCTION.
B). ACCLIMATIZATION

5. A). INTRODUCTION
 Introduction of a Plant from their Native place to
Another place
which having different Climate.
 Sexually Reproducing plants introduced by
means of Seeds.
 Vegetatively Reproducing plants introduced by
means of Cutting,
Layering, Graft, Bulb & Tubers.

6. B). ACCLIMATIZATION
 For Successful introduction, The introduced plant
has to Adopt
itself to grow he New area.
 Ability of Introduced plant to Survive in the New
Climate & Soil Condition.

7. BREEDING METHODS
 A). Inbreeding
B). Outbreeding
C). Heterosis

8. INBREEDING
 Mating of Parents who are Closely Genetically
related.
 Results in Increased Homozygosity which can
increase the Chance of
 Offspring being affected by Recessive traits.

9. METHOD OF INBREEDING
 Marriage between Brother and Sister is an Ideal
Inbreeding.
 Royal Family of Egypt Cleopatra was famous for
inbreeding between
Brothers and Sisters.
 In Plants, It Occurs in the Form of Self Pollination.

10. RESULTS OF INBREEDING
 Reduced Fertility both in Litter size and in
 Sperm viability.
 Increased Genetic Disorders.
 Lower Birthrates
 Higher Infant Mortality
 Slower Growth rate.
 Loss of Immune System function.

11. MERITS & DEMERITS
MERITS OF DEMERITS OF
INBREEDING INBREEDING
 A) Increase of  A) Low yield
Homozygotes, B) Inbreeding
B) Production of Pure Depression
lines. C) Appearance of
C) Elimination of Deleterious
Deleterious Characters.
Recessive
Characters.
D) Production of
Valuable Breeds.

12. OUTBREEDING
 Mating of Unrelated individuals
 Also known as Cross Breeding.
 The offspring formed by mating of Two unrelated
parents.

13. TYPES OF OUTBREEDING
A) INTRASPECIFIC : Matting between Members
of Same Species.
B) INTERSPECIFIC : Matting between Members
of Different Species.
C) INTERGENERIC :
Matting between the Members of Different
Genera.

14. TYPES OF OUTBREEDING
INTERSPECIFIC INTERGENERIC

15. Examples of Outbreeding
 Mendel carried Outbreeding between a Tall pea
plant and a Dwarf pea plant.
 The Resulting plants are Hybrids.
 These Parents differe in Only one Character.
 So these Hybrids are called as Monohybrids.
TALL X DWARF
TT X tt
|
Tall
Tt

16. RESULTS OF OUTBREEDING
A) Numerous varieties of better Yielding crop
plants.
B) Paddy hybrids produce more Grains.
C) Tall and Dwarf coconut hybrid yields more
number of Nuts
D) Caddish is a hybrid Between Cabbage and
Radish
E) Pomato is a hybrid between Potato and
Tomato.

17. HETEROSIS BREEDING
 The Increased growth vigour or yield of hybrids
over the Parents is
known as Heterosis or Hybrid vigour.
 Crop breeding to manifest heterosis is called
Heterosis breeding.
 It brings out the Superiority in F1 individuals but
the vigour tends to Decrease from F2 generation
onwards.

18. HETEROSIS BREEDING
 Heterosis means Deviation of Offspring from the
Actual Character of Parents.
 In Plants, Heterosis appears due to
Developmental stimulation induced by the Union
of Gametes coming from Two genetically
complementing parents.

19. THEORIES OF HETEROSIS
 Two Popular Hypotheses to explain Heterosis in
F1
A) Dominance Hypothesis
B) Over Dominance Hypothesis

20. DOMINANCE HYPOTHESIS
 Hybrid vigour results from bringing together the
Maximum number of
Dominant Favourable genes in F1 hybrids.
 Favourable genes - Dominant genes.
 Unfavourable genes - Recessive genes.

21. EXAMPLE
 KKggPPnnRR and kkGGppNNrr are codes from
Ear length.
Parent-1 Parent-2
KKggPPnnRR x kkGGppNNrr
K+P+R= 15 cm x k+p+r= 3 cm
g+n = 2 cm x G+N= 10 cm
Total = 17 cm Total = 13 cm
 Each of
Dominant genes = 5 cm
Recessive genes = 1 cm

22.  F1 -> KkGgPpNnRr
K+G+P+N+R = 25 cm
 So the Hybrid vigour results from bringing
together the Maximum number of
Dominant Favourable genes in F1 hybrids.

23. OVER DOMINANCE
HYPOTHESIS
 Hybrid vigour due to Superiority of Heterozygotes
over the Homozygotes .
 Allelic Combinations are more vigour than single
Allelic expression.

24. EXAMPLE
 A1, A2, A3, A4 are Alleles with Different functions
A1 x A1 A2 x A2
| |
A1A1 A2A2
 So the A1A2, A1A3, A1A4 are more vigour than
A1A1 and A2A2.
 Thus Hybrid vigour is due to Superiority of
Heterozygotes over the Homozygotes is called
Over Dominance.

25. METHOD FOR HETEROSIS
BREEDING
 Methodology of Heterosis breeding varies with
Different crops.
 Depending on their nature of Pollination, Sexual
incompatability and other reasons.
 This includes main three types
1) Producing inbred lines.
2) Testing of Combining ability of Inbred lines.
3) Production of Hybrid seeds.

26. EFFECTS OF HYBRID VIGOUR
1. Roots of Carrot.
2. Leaf of Spinach and Lettuce.
3. Flowers in Cauliflower.
4. Fruits in Cucurbits, Brinjal. Peas, etc.

27. ADVANTAGE & DISADVANTAGE
ADVANTAGE DISADVANTAGE
1. In many crops, F1 1. Production cost is
hybrids are Early in
Maturity. High.
EX : Cabbage, Onion,
Tomato etc. 2. Fresh seeds is to be
2. They produce goods Purchased every
with Uniform size. time to raise new
Ex : Onion and
Cabbage. crop.
3. They are resistance to 3. Sometimes F1
Biotic and Abiotic
stresses. hybrids are
Ex : Cucumber, Tomato Vulnerable to
and Onion.
4. They are always high
disease.
yielding varieties

28. Thank you….