Abstract

A field and glass house experiment was conducted with the aim of evaluatingRhizobium inoculation, molybdenum (Mo) and lime supply on growth and nitrogen fixation of nodulated Phaseolus vulgaris. The experiment was laid in a split-split plot design. The experimental treatments consisted of 2 levels ofRhizobium inoculation (with rhizobia and without rhizobia) 3 levels of Mo (0, 6 and 12 g kg^-1 of seeds) and 3 levels of lime (0, 2 and 3 t ha^-1). Rhizobiuminoculation showed significant increase in dry matter yield of different organs and decreased δ¹⁵N values in all organs assessed, thus resulting to improved % nitrogen derived from atmosphere (%Ndfa) in all organs and the amount of N derived from fixation. Molybdenum and lime were significantly effective in promoting plant growth in most organs and decreased δ¹⁵N values in all organs for glasshouse and field experiment. Lowest δ¹⁵N values were recorded in Mo and lime supplied at the highest rates of 6 and 12 g kg^-1 of seeds and 2 and 3 t lime per ha, respectively. Molybdenum and lime application also significantly improved %Ndfa in all organs and N derived from N-fixation in most organs. Significant responses in N nutrition were also reported in treatments involving the combination of Rhizobium x Mo x lime with better result being recorded in treatments involving Rhizobium inoculation and higher levels of Mo and lime.

Key words: Nodulated root, δ¹⁵N, %Ndfa, total N.