Clonal selection

This presentation includes the basic method of clonal selection and its application in crops, its merits, and its demerits.

1. CLONAL SELECTION Submitted by: Sushrut Mohapatra 201222105

2. CLONE Progeny of a single 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 Homogenous constitution : 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 GENETIC VARIATION WITHIN CLONES 1. Somatic mutation 2. Mechanical mixture 3. Sexual reproduction 4. Segregation in F1

5. CLONAL DEGENERATION The loss 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 Sugarcane Degeneration 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. I n 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 Improvement of 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 of clonal selection FIRST YEAR : 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. SECOND YEAR Clones from the selected plants grown separately. Desirable clones selected

11. THIRD YEAR Preliminary yield 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 Multilocation yield trials with standard checks. Best clone is identified for release as a new variety.

13. SEVENTH YEAR The best clone is released as a new variety. Seed multiplication for distribution begins.

14. SCHEMATIC DIAGRAM FOR CLONAL SELECTION

15. MERITS 1) Useful in 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) Highly prone to new disease of new Races. 2) Can't create new variability.

17. ACHIEVEMENTS OF CLONAL SELECTION Crop Clonal Variety 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 from Darjeeling Red Round Kufri Safed from Phulwa

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