Managing Global Genetic Resources Agricultural Crop Issues and Policies (1993) / Chapter Skim
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6. Using Genetic Resources
6. Using Genetic Resources
Pages 173-188
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From page 173... ...
Explorers returned to Europe with Ne`^`r World species that greatly influenced European agriculture. The potato became one of the most important energy foods in Europe, and tomato and corn ultimately achieved status as major crops.
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From page 174... ...
In the hard red winter wheat area, breeders firmly maintained the core of Turkey wheat germplasm over the years, thus preserving the basic adaptation, yield stability, and product quality of Turkey wheat while improving specific agronomic and quality characteristics. By 1984 the number of commercially grown varieties had increased to 164, but this increase was accompanied by higher than desirable genetic relatedness of the primary cultivars (cultivars that occupied 1 percent or more of the land planted to wheat)
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From page 175... ...
Monitoring Advanced Materials Many breeders (including farmers who practice selection) regularly monitor advanced materials, especially commercially grown cultivars, for potentially useful variants; many useful alleles with major effects on characteristics such as early maturity, height, determinant versus indeterminant growth habit, cold or heat tolerance, and resistance to diseases and insects have been uncovered in this manner.
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From page 177... ...
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From page 178... ...
Breeders turn more and more frequently to such populations, because they often provide many different alleles for specifically sought-after traits concentrated from numerous sources into genetic backgrounds that provide adaptedness to specific ecological regions. Among the heaviest users of accessions from active collections are the breeders of those plant species that have little or no history of breeding improvement.
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From page 179... ...
in active collections contribute useful alleles. Breeders who initiate plant improvement programs for such species or areas often have no alternative to evaluating primitive materials and selecting as parents either the more promising accessions or superior individuals within promising accessions.
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From page 180... ...
Thus, most countries, developed or not, accept the proposition that if the food, feed, fiber, and other agricultural needs of an ever-increasing world population are to be met, a significant part of the increase must come from genetic improvement of plants and that adequate supplies of useful germplasm are essential for genetic improvement. Nevertheless, despite the continuing need for genetic diversity, it has often been stated that only limited use is being made of the germplasm resources maintained in national, regional, and international collections.
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From page 181... ...
to be transferred by breeding into locally adapted genotypes. The most common type of active collection, a breeding collection, is intended to serve as a reservoir of alleles governing specific traits to be transferred, by appropriate breeding methods, into locally adapted genotypes.
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From page 182... ...
Where collections are large, management strategies, such as the designation of core subsets, may also be needed (see Chapter 5~. Obsolescence A disproportionate number of accessions obsolete and are unlikely to serve as useful i in active collections are germplasm in modern breeding programs or in modern basic genetic, cytogenetic, or ecogenetic studies.
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From page 183... ...
MODERNIZATION OF ACTIVE COLLECTIONS Often, outstandingly useful modern materials do not find their way into germplasm collections. There are at least five main sources of new accessions: · New elite lines and cultivars developed by breeders; · Obsolete but historically important cultivars and stocks (including privately developed stocks)
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From page 184... ...
These examples illustrate an essential step in using germplasm, which is the transfer of desired genetic traits into breeding lines that have agronomic, physiologic, and morphologic traits compatible with modern production systems. Other examples of such efforts include the Latin American Maize Project and the government, industry, and university cooperative effort in
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From page 185... ...
Within a few years many outstanding lines had been selected from CC II, including more than 50 lines that became named varieties, as well as numerous other lines that were used as parents in networks of subsequent successful crosses. Furthermore, long-term genetic studies have shown that the 28 parents of CC II contributed much of the total agriculturally relevant variability of the entire barley species to the population and that very useful evolutionary changes continued in CC II for more than 50 generations when it was grown under standard agricultural conditions in each of a number of ecogeographic regions (Allard, 1988~.
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From page 186... ...
The usefulness of the barley CC II and the maize Iowa Stiff Stalk Synthetic populations as sources of germplasm has stimulated the initiation of many different kinds of germplasm enhancement programs based on carefully selected materials in a number of different species. As enhanced germplasm has become more widely known and available, breeders have increasingly turned to such sources and away from traditional collections, in which variability is stored in a static state.
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From page 187... ...
Germplasm workers should strive to become active partners in germplasm evaluation, enhancement, and use by contributing their knowledge on and experience with unimproved germplasm.
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