Fluorescence in soybean roots was first described by Chmelar (1934) and by Chmelar and Mostovoj (1934). Reports of nonfluorescing root phenotypes in both Glycine max and G. soja have been made by Grabe (1957), Fehr and Giese (1971) and Broich (1978). Genetics studies by Delannay and Palmer (1982) indicate that absence of root fluorescence in G. max is controlled by four independent genes; three of these genes are recessive (fr1, fr2 and fr4) and one is dominant (Fr3).