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Clonal selection
- 1. CLONAL SELECTION Submitted by: SushrutMohapatra 201222105
- 2. CLONE Progeny of asingle plant obtained by asexual reproduction is known as Clone These are the crops which are propagated by asexual or vegetative means.
- 3. FEATURES OF CLONES Homogenousconstitution: Plants of a clone have similar genetic constitution Heterozygosity:They are highly heterozygous though phenotypically similar Lack of genetic variation: Phenotypically variation present within a clone is due to environmental effect not genetically Immortality: Maintained by asexual reproduction Vigorous growth: Clonal selection is useful in conserving the heterosis for a long period of time Wider adaptation: Due to high level of heterozygosity than pure lines
- 4. ORIGIN OF GENETICVARIATION WITHIN CLONES • 1. Somatic mutation •2. Mechanical mixture •3. Sexual reproduction •4. Segregation in F1
- 5. CLONAL DEGENERATION • Theloss in vigor and productivity of clone with time is known as clonal degeneration. • Clonal degeneration- Degeneration is inherent in the clone. Degeneration may result from • 1) Mutation • 2)Viral diseases • 3) Bacterial diseases
- 6. Degeneration in SugarcaneDegeneration in potato
- 7. METHODS OF IMPROVEMENT •Asexually propagated crops differ from sexually propagated ones in one basic aspect that their breeding materials and the commercial varieties are maintained through asexual reproduction as against sexual reproduction in the case of latter. This provides some unique advantages and opportunities in breeding of these crops. • In the case of sexually reproducing crops, breeding of clonal crops has the following two well defined phases: • (1) Creation of genetic variation (either by natural processes or by human activity like hybridization) • (2) Selection of the best genotype from the variable population to produce a superior clone or variety.The procedure of selection used for such crops is known as clonal selection since the selected plants are used to produce new clones
- 8. CLONAL SELECTIONS • Improvementof asexually propagated crops by selecting superior clones is known as clonal selection. Superior clones can be isolated from three types of materials • 1- Local variety • 2-Introduced variety • 3-Intercrossed population
- 9. Breeding procedure ofclonal selection • FIRSTYEAR : • a) From a mixed variable population, few hundred to few thousand desirable plant are selected. • b) A rigid selection can be done for simply inherited characters with high heritability. • c) Plant with obvious weakness are eliminated.
- 10. SECONDYEAR • Clones fromthe selected plants grown separately. • Desirable clones selected
- 11. THIRD YEAR • Preliminaryyield trials with standard checks. • a) Selection for quality, disease resistance etc. Disease nurseries may be planted. • b) Few outstanding clone selected.
- 12. FOURTH-SIXTH YEAR • Multilocationyield trials with standard checks. • Best clone is identified for release as a new variety.
- 13. SEVENTH YEAR • Thebest clone is released as a new variety. • Seed multiplication for distribution begins.
- 14. SCHEMATIC DIAGRAM FORCLONAL SELECTION
- 15. MERITS • 1) Usefulin conserving heterosis for several generations i.e. method retains all the characteristic of the parental clone for several years. • 2) Highly uniform and stable • 3) Effective method for genetic improvement of asexually propagated crop plants.
- 16. DEMERITS • 1) Highlyprone to new disease of new Races. • 2) Can't create new variability.
- 17. ACHIEVEMENTS OF CLONAL SELECTION CropClonalVariety Papaya CO-1, CO-2, CO-5, CO-6, Pusa giant, Pusa dwarf Pineapple Singapore Spanish, MasmerahPuerto Rico Litchi glorff,Saharanpur sel, swarna roopa Aonla NA-4, NA-5, NA-6, NA-7,NA-8, NA-10 Pomegranate G-137,CO-1,YCD-1 Bael NB-1,NB-5, NB-6 Mango Dasehari-51, Niranjan, Cardoz mankurad, Payur-1 Grapes Pusa seedless,Thomson seedless, Perlet, Tas-e ganesh, Sonaka, Rao sahebi, dilkhus
- 18. Kufri Red fromDarjeeling Red Round Kufri Safed from Phulwa
- 19.