| Abstract: | Inbreeding depression observed in Medicago sativa L. is greater in the early generations of self-fertilization than is expected for an autotetraploid based upon the coefficient of inbreeding (F). Forage yield often is reduced by 30 percent or more after one generation of selfing, while F is only one-sixth,  =0. A high frequency of loci containing 3 or 4 different alleles is postulated as a basis for this rapid loss of vigor. A formula is developed that permits computation of the proportions of loci with 1, 2, 3 and 4 different alleles, along with estimates of additive and non-additive values of genes.Forage yield data for backcross and sib-mated populations indicate that quantitative characters are inherited tetrasomically.Journal Paper No. J-5190 of the Iowa Agricultural and Home Economics Experiment Station. Project 1048.Graduate Assistant and Professor of Agronomy, Department of Agronomy, Iowa State University, Ames, Iowa. |
