Efficacy of Indigenous Rhizobial Strains for Nitrogen Fixation and Yield of Soyabean (Glycine Max (L.) Merill) in the Rainforest Transition Zone
Ojo Abisoye Oyepero; Dare, Michael Olajire

Production of efficient indigenous rhizobial inoculants for seed inoculation can improve soyabean yield and biological N fixation. The performance of indigenous rhizobial isolates: TRC2, IDC8, OISa-6e, R25B, IRj1280A on nodulation, N fixation and yield of soyabean varieties TGx1448-2E, TGx1908-1F and TGx1910-2F were studied in three study sites: University of Ibadan Teaching and Research Farm (UITRF), Idi Ayunre (IA) and Orile Ilugun (OI). Low rhizobial count (< 14 cell g-1 soil) of the sites seemed to favour competitiveness of the inoculated strains against resident rhizobial population for nodule occupancy. Nodulation, grain yield and N fixation were increased by inoculation in IA and UITRF. The indigenous isolates OISa-6e and IDC8 showed relatively high level of compatibility with TGx1448-2E at UITRF and IA with significantly (P<0.05) higher nodulation, grain yield and total N fixed compared to uninoculated plants. Minimum increase of 0.4 t/ha in grain yield and 40 kg/ha N in total N fixed were observed when soybean inoculated with OISa-6e and IDC8 were compared with uninoculated control. Variable soil biological and chemical properties of the study sites and soyabean varietal compatibility with rhizobial strain were critical to the efficiency of rhizobial inoculation. The study revealed the potentials of indigenous rhizobial strains for use as inoculants to increase soyabean production.

Full Text: PDF     DOI: 10.15640/jaes.v9n1a4