1. PLANT BREEDING METHODSSUBMITED BY,M. THILAKAR,LS1154SECOND
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 PlantbreedingM 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.
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 & DEMERITSMERITS OF DEMERITS OFINBREEDING
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 OUTBREEDINGA) INTRASPECIFIC : Matting between
Membersof Same Species.B) INTERSPECIFIC : Matting between Membersof
Different Species.C) INTERGENERIC :Matting between the Members of
DifferentGenera.
14. TYPES OF OUTBREEDINGINTERSPECIFIC 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 OUTBREEDINGA) Numerous varieties of better
Yielding cropplants.B) Paddy hybrids produce more Grains.C) Tall
and Dwarf coconut hybrid yields morenumber of NutsD) Caddish is a
hybrid Between Cabbage andRadishE) Pomato is a hybrid between
Potato andTomato.
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 DOMINANCEHYPOTHESIS 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 HETEROSISBREEDING 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 VIGOUR1. Roots of Carrot.2. Leaf of
Spinach and Lettuce.3. Flowers in Cauliflower.4. Fruits in
Cucurbits, Brinjal. Peas, etc.
27. ADVANTAGE & DISADVANTAGEADVANTAGE DISADVANTAGE1. In
many crops, F1 1. Production cost is hybrids are Early in Maturity.
High. EX : Cabbage, Onion, Tomato etc. 2. Fresh seeds is to be2.
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