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PLANT BREEDING METHODSSUBMITED BY,M. THILAKAR,LS1154SECOND YEAR.M.SC IN LIFE SCIENCES,BHARATHIDASAN UNIVERSITY,TIRUCHIRAPALLI.
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.
Popular scientists in PlantbreedingM S SWANI NAATHAN VENKATARAMANAN
Introduction of Plants Process plants introduced from their Native place to Another place for Crop Improvement. A). INTRODUCTION. B). ACCLIMATIZATION
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.
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.
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.
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.
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.
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.
OUTBREEDING Mating of Unrelated individuals Also known as Cross Breeding. The offspring formed by mating of Two unrelated parents.
TYPES OF OUTBREEDINGA) INTRASPECIFIC : Matting between Membersof Same Species.B) INTERSPECIFIC : Matting between Membersof Different Species.C) INTERGENERIC :Matting between the Members of DifferentGenera.
TYPES OF OUTBREEDINGINTERSPECIFIC INTERGENERIC
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
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.
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.
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.
THEORIES OF HETEROSIS Two Popular Hypotheses to explain Heterosis in F1 A) Dominance Hypothesis B) Over Dominance Hypothesis
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.
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
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.
OVER DOMINANCEHYPOTHESIS Hybrid vigour due to Superiority of Heterozygotes over the Homozygotes . Allelic Combinations are more vigour than single Allelic expression.
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.
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.
EFFECTS OF HYBRID VIGOUR1. Roots of Carrot.2. Leaf of Spinach and Lettuce.3. Flowers in Cauliflower.4. Fruits in Cucurbits, Brinjal. Peas, etc.
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