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The genetic base of brazilian soybean (Glycine max (l.)merrill) cultivars

D.M. Hiromoto; N.A. Vello

Departamento de Genética, ESALQ, USP, Caixa Postal 83, 13400 Piracicaba, SP, Brasil. Send correspondence to N.A.V.

ABSTRACT

Pedigrees were assembled and examinated to identify ancestral lines of the 74 Brazilian soybean (Glycine max (L.) Merrill) cultivars of hybrid origin. Original ancestors were assumed to be unrelated so that Malecot's coefficient of parentage could be calculated for each cultivar. Brazilian soybean cultivars could be traced to only 26 original ancestors. Eleven such ancestors collectively represent 89%; of the Brazilian gene pool; six of these ancestors also were the most frequent in the pedigrees of USA cultivars. Soybean cultivar development in Brazil can be considered to be the third cycle of a recurrent selection program. In order to overcome yield plateaus and to avoid the risk of genetic vulnerability, the enhancement of the genetic base of Brazilian soybean gene pools was emphasized. Exotic soybean genotypes present in genetic resource centers and future introductions from the center of origin and centers of diversity should be used as parents. Selected exotic germplasm can be introduced by making three- or four-way crosses, by crossing and backcrossing to a recurrent parent, or by introducing into an intermating population with a broad genetic base (N 30).

Keywords: genetic; soybean; Glycine max.

REFERENCES

Bos, I. (1977). More arguments against intermating F₂ plants of a self-fertilizing crop. Euphytica 26: 33-46.

Cregan, P.B., Yocum, J.O., Justin, J.R. and Buss, G.R. (1981). Evaluation of soybean introductions, ancestral varieties, and cultivars. Agron. Abstr. Am. Soc. Agron. 59.

Delannay, X., Rodgers, D.M. and Palmer, R.G. (1983). Relative genetic contributions among ancestral lines to North American soybean cultivars. Crop. Sci. 23: 944-949.

Dudley, J.W. (1982). Theory for transfer of alleles. Crop. Sci. 22: 631-637.

Dudley, J.W. (1984). A method for identifying populations containing favorable alleles not present in elite germplasm. Crop. Sci. 24: 1053-1054.

EMBRAPA (1982). Catálogo de Germoplasma de Soja. CENARGEN, Brasília, pp. 192.

Falconer, D.S. (1981). Introduction to Quantitative Genetics. 2nd edn. Longman, New York, pp. 340.

Hymowitz, T., Newell, C.A. and Carmer, S.G. (1977). Pedigrees of soybean cultivars released in the United States and Canada. Urbana, INTSOY Series Number 13, pp. 32.

Jensen, N.F. (1978). Composite breeding methods and the DMS system in cereals. Crop. Sci. 18: 622-626.

Kempthorne, O. (1973). An Introduction to Genetic Statistics. Second printing. Iowa State University Press, Ames, pp. 545.

Kenworthy, W.J. (1980). Strategies for introgressing exotic germplasm in breeding programs. In: World Soybean Research Conference II: Proceedings. (Corbin, F.T., ed.). Westview Press, Boulder, pp. 217-223.

Miyasaka, S. and Medina, J.C. (eds.) (1981). A Soja no Brasil ITAL, Campinas, pp. 1062.

NAS-NRC (1972). Genetic Vulnerability of Major Crops. Report of the Committee on Genetic Vulnerability of Major Crops, Agricultural Board, Division of Biology and Agriculture, National Research Council. Washington, D.C., National Academy of Sciences, pp. 307.

Sediyama, T., Destro, D., Sediyama, C.S., Tragnago, J.L., Carraro, I.M. and Costa, A.V. (1981). Caracterização de Cultivares de Soja. Universidade Federal de Viçosa, Viçosa, pp. 81.

Specht, J.E. and Williams, J.H. (1983). Contribution of genetic technology to soybean productivity-retrospect and prospect. In: Genetic Contributions to the Yield Gains in Five Major Crop Plants (Fehr, W.R., ed.). Special Publication No. 7, Crop Science Society of America, Madison, pp. 49-74.

St. Martin, S.K. (1982). Effective population size for the soybean improvement program in maturity groups 00 to IV. Crop. Sci. 22: 151-152.

Vello, N.A., Fehr, W.R. and Bahrenfus, J.A. (1984). Genetic variability and agronomic perfor- mance of soybean populations developed from plant introductions. Crop. Sci. 24: 511-514.

Vello, N.A. (1985). Efeitos da introdução de germoplasma exótico sobre a produtividade e relações com a base genética das cultivares de soja (Glycine max (L.) Merrill). "Livre-Docência" Thesis, ESALQ, USP, pp. 91.