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Current Category » Breeding of Field and Horticultural Crops

Definations in Germplasm

1. Gene Pool:

The whole library of different alleles or sum total of genes in a species. Also called germplasm, genetic stock and genetic resources.

2. Indigenous Collection:

The Germplasm which is collected within the country.

3. Exotic Collection:

The Germplasm which is collected or received from other countries.

4. Base Collections:

Total accessions available in a crop. These are used for long storage ( upto 100 years). Seeds are stored at 18 or 20 0C ; also called Principal collection.

5. Active Collections:

Collections which are actively utilized in the breeding programmes and are used for medium term storage (8 -10 years). Seeds are stored at 0 0C.

6. Working Collections:

Collections which are frequently utilized by breeders in their crop improvement programmes. These are stored for short term (3-5 years) at 5-10 0C.

7. Core Collection:

A set of accession derived from base collections to represent the genetic spectrum in the whole collection.

8. Characterization:

Recording of highly heritable phenotypic characters.

9. Primary Gene Pool:

The gene pool in which intermating is easy and leads to production of fertile hybrids. It includes genotype of same species. It is designated as GP1.

10. Secondary Gene Pool:

The genetic material that leads to partial fertility on crossing with primary gene pool. It includes genotypes of related species and is designated at GP2.

11. Tertiary Gene Pool:

The genetic material which leads to production of sterile hybrids on crossing with primary gene pool. It is designated as GP3.

12. Land Races:

The primitive cultivars which were selected and cultivated by farmers for many generations. Land races have more genetic diversity, wider adaptability and high degree of resistance to biotic and abiotic stresses.

13. Obsolete Cultivars:

The improved cultivars of the recent past.

14. Modern Cultivars:

The currently cultivated high yielding varieties.

15. Genetic Erosion:
 
Gradual reduction in genetic variability due to elimination of various genotypes. It results due to use of modern cultivars, modernization of agriculture and various development activities.

16. Conservation:

The protection of genetic diversity from genetic erosion under natural conditions or by storing in gene banks.

17. In Situ Conservation:

Conservation of germplasm under natural condition.

18. Ex Situ Conservation:

Preservation of germplasm in the gene banks.

19. Orthodox Seeds:

Seeds which can be dried to low moisture content and stored at low temperatures without losing their viability.

20. Recalcitrant Seeds:

Sees which show very drastic loss in viability with decrease in moisture content below 12 to 13%. Such species include coconut, mango, tea, coffee, rubber, jackfruit, oil palm, etc. such seeds can not be conserved in seed tanks.

21. Documentation:

The process of compilation, analysis, classification, storage, and distribution of information.

22. Quarantine:

The prophylactic measures that is used to prevent the entry of new diseases, insects and weeds from other countries.

Current Category » Breeding of Field and Horticultural Crops