The Rj2 gene (Caldwell, 1966), which conditions ineffective nodulation wtth strains of the cl and 122 serogroup of Rhizobium japonicum (Kirchner) Buhanan, and the Rj4 gene (Vest and Caldwell, 1972), conditioning an inef-fective nodulation response with rhizobial strain 61 of the Beltsville Culture Collection R. japonicum, were tested for linkage association with the gene L1 (black pod). The rj1 gene (Williams and Lynch, 1954), conditon-. ing a non-nodulating response with a broad spectrum of strains of R. Japonicum, was tested for linkage with the gene fr (roots nonfluorescent in UV light) and L1 (black pod). The gene y9 (chlorophyll defective) was tested for possible linkage with the genes ln (narrow leaf), and P1 (glabrous). The P1 gene was also tested for linkage with the gene fr.