| Abstrakt: |
An examination of the pedigrees for 158 USA and Canadian soybean [Glycine max(L.) Merr.] cultivars of hybrid origin indicated that the North American soybean gene pool could be traced to only 50 plant introductions. Evaluations were made of the relative genetic contributions of those introductions to the cultivars released in the northern and southern gene pools of North America over four time periods, i.e., before 1951, 1951–1960, 1961–1970, and 1971–1981. Although more introductions have been used in recent times, a few constitute an increasingly greater proportion of the genetic base for our modern cultivars. Ten introductions contributed, collectively, more than 80% of the northern gene pool, while only seven contributed the same share to the southern gene pool. Furthermore, many of the predominant introductions originated from the same geographic area. These data confirm previous estimates of the narrowness of the genetic base for present‐day soybean cultivars. Examples, however, are provided describing the recent use of new introductions in the development of soybean cultivars. |
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