A nodulation type with increased number of nodules and nitrate intolerance in soybean

Abstract

Kitamusume, a cultivar of soybean (Glycine max L. Merr.), exhibits a novel nodulation type which carries a larger number of nodules, but is not nitrate tolerant. Soybean plants (cvs. Kitamusume, Toyosuzu, Enrei, and Tachiyutaka) were grown in pots filled with 3 kg of used commercial soil containing 23.9 mg kg^-1 of inorganic nitrogen. They were inoculated with A1017, a strain of Bradyrhizobium japonicum, at sowing. The plants were harvested at 61 days after sowing. Kitamusume had 213.3 nodules, while other cultivars had 142.3 – 152.3 nodules. In another experiment, plants (cvs. Kitamusume and Toyosuzu) were grown in pots containing 23.9 (control), 63.1, 107.3, 169.6, and 291.5 mg kg^-1 inorganic nitrogen and inoculated as above. They were harvested at 35 days after sowing. The number of nodules of both cultivars decreased approximately 60, 40, and 0% of that of the control, in soil containing 107.3, 169.6, and 291.5 mg kg^-1 inorganic nitrogen, respectively.