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United States Department of Agriculture

Agricultural Research Service

Title: A Testcross Procedure for Selecting Exotic Strains to Improve Pure-Line Cultivars

Authors
item St Martin S K, - OHIO STATE UNIV
item Lewers K S, - ISU
item Palmer, Reid
item Hedges B R, - AGRICULTURE CANADA

Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 7, 1995
Publication Date: N/A

Interpretive Summary: Our agricultural economy is vulnerable to changes in the environment in which crops are grown. These changes include outbreaks of crop pests, deterioration of land, air and water quality, and an increasingly variable weather pattern. Modern agriculture depends on crop breeders to develop cultivars that produce high yields in these diverse and ever-changing environments. Crop breeders do this by increasing the diversity of parental plant material used for cultivar development. They must choose parental materials that contain new and different genes for high yield, stress tolerance and pest resistance. An efficient test is needed to identify these new and different genes from among thousands of parental materials a crop breeder can use, especially for self-pollination crops such as soybean. We developed such a test and related mathematical formulae. We also used published data to evaluate the test's usefulness to crop breeders. The test is practical because it can be used even when the genetic inheritance of a crop's important traits is not fully understood. Breeders of self-pollinating crops can use this test to efficiently choose parental plant materials that have new and different genes for high performance in diverse environments.

Technical Abstract: Methods for identifying germplasm carrying alleles with the potential to improve a particular single-cross hybrid have been proposed and discussed in recent years. There is a need for similar methods to be used in breeding crops where pure-line cultivars are the goal. The objective of this research was to develop a method to identify germplasm lines with the potential to contribute favorable alleles not present in a specified pure line or set of pure lines. Given a set of adapted lines to be improved and a set of germplasm lines, the procedure consists of producing all possible germplasm line by adapted line hybrids and evaluating them with parents. The defined test statistic is derived from the performance of a specific adapted line, a specific germplasm line, and their hybrid. This statistic measures the potential for alleles from a specific germplasm line to improve a specific adapted line. A second defined statistic is the mean value of the first statistic over all adapted parents. This statistic measures the potential for alleles from a specific germplasm line to improve the set of adapted parents. Use of published data on soybean and peanut hybrids suggests that the degree of dominance has little effect on which germplasm line is chosen. The ability of the two defined statistics to identify germplasm strains carrying rare favorable alleles should be assessed in empirical studies.

Last Modified: 8/1/2014
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