To obtain soybean (Glycine max. L. Merr.) lines harboring the Rj 2- and Rj 4-genes, the Rj 2-cultivar IAC-2 (Genotype Rj 2Rj 2rj 4rj 4) and Rj 4-cultivar Hill (rj 2rj 2Rj 4Rj 4) were crossed. Genotype Rj 2Rj 2Rj 4Rj 4was selected based on its nodulation reactions with the combined inoculum of Brady rhizobium japonicum strains Is-1 (nodulation-type B; nodulates the Rj 4-cultivar but does not nodulate the Rj 2-cultivar) and Is-34 (type C; nodulates the Rj 2Rj 3-cultivar but does not nodulate Rj 4-one). In the F1and F2generations, both Rj-genes segregated according to Mendel's laws. The genotype of the F2plant could be considered to be Rj 2Rj 2Rj 4Rj 4if all the tested progenies from the F2plant nodulated ineffectively with the combined inoculum. Ten progenies from each of eight F2plants were assayed for the Rj-phenotypes and four promising F2-plants were isolated. The progenies (F3generation) from the selected lines were transplanted in the field, and the F4progenies were examined for their compatibility with the combined inoculum strains. Three promising lines homozygous for both Rj 2- and Rj 4-genes and one line homozygous for Rj 2and heterozygous for Rj 4were isolated. The progenies (F5generation) from the selected lines were examined for their compatibility with the combined inoculum strains, and it was eventually concluded that 12 lines (F4generation) were characterized by the genotype Rj 2Rj 2Rj 4Rj 4.
All Science Journal Classification (ASJC) codes
- Soil Science
- Plant Science