The effect of interspecific hybridization on certain genetic ratios in sweet clover

Abstract

During recent years sweet clover has become more and more recognized as an important agricultural crop. Consequently, considerable effort has been placed in the improvement of its agronomic characters. The breeding of improved varieties made more intensive studies of the crop necessary. Genetic studies have been conducted on many characters. In a number of studies, inter- and intraspecific fertility has been determined and techniques of selection have been developed. In many of the genetic studies simple mendelian segregation occured. At the Dominion Forage Crops Laboratory at Saskatoon, where particular emphasis is placed on the development of coumarin-deficient strains of sweet clover, a study of the mode of inheritance of coumarin content was undertaken in 1954. Many of the F2 progenies segregated 3:1 for high vs. low coumarin content. The same segregation occured with respect to free vs. bound coumarin. In some F2 progenies, however, unexpected ratios of approximately 8 high-coumarin to 1 coumarin-deficient plants occured. Some type of complementary inheritance was suggested as a possible explanation for these ratios. The present study was undertaken to determine the cause of the unexplained segregation in several F2 populations. A new method of testing sweet clover seeds for coumarin was evaluated with regard to its applicability in breeding work.