Seeds of fenugreek (Trigonella foenum - graecum L.) either irradiated (100 Gy) or non-irradiated were sown under clay soil conditions. Both seeds were inoculated with Rhizobium strains to assess the bacterial-plant symbiosis performance as affected by nitrogen fertilizer rates. Un-inoculated control was also included. ¹⁵N labeled ammonium sulfate enriched with 5% atom excess was applied at 20 and 40 kg N fed^-1, in addition to non-fertilized treatment to trace and quantify portion of N derived from air (Ndfa).Vegetative growth parameters like shoot length, shoot and pod dry weights, 1000-seeds weight, and nodulation criteria (numbers and dry weight) were significantly enhanced by increasing N fertilizer rates, Rhizobium inoculation and irradiation dose. Raising N fertilizer rate had increased the growth attributes as well as nitrogen and phosphorus uptake by pods and shoots. Rhizobium inoculation improved the plant growth and compensated remarkable amount of nitrogen derived from air (Ndfa) to both plant organs. Fenugreek seeds exposed to gamma ray at low dose reflected positive significant response which translated into good growth attributes and nutrients uptake as well as effective Rhizobium-fenugreek symbiosis performance. This combined strategy as low cost effective and safe could be accepted to ensure remarkable fenugreek production with good quality under such given conditions.