Abstract

The potency and competitive ability of indigenous rhizobia population in soil to nodulate a non-native legume host has been contentious especially in tropical Africa. This study examined the symbiotic compatibility between the indigenous rhizobia population and a non-native legume species. Soil samples were randomly collected with soil auger at 0 - 30 cm depth from agricultural fields southeast, Nigeria. The control soil samples were obtained from the Badagry beach which had no previous history of legume cultivation at the same depth. Mucuna pruriens seeds were aseptically sown in plastic pots containing these soils kept in the greenhouse for 10 weeks. The test pots were watered with sterile distilled water while the control pots received inorganic nitrogen (N)  as source of N nutrient. The agronomic features of the host legume were evaluated after 10 weeks and the presence of appropriate Rhizobium inoculant contributed positively to biomass production in M. pruriens. The Mucuna microsymbiont was found to thrive under favorable climatic and edaphic factors for effective nodulation of the host legume. The microsymbiont was identified on yeast-extract mannitol salt agar (YEMA) containing bromothymol blue (BTB) as Bradyrhizobium and Rhizobium species. This study convincingly showed the importance of rhizobia to soil fertility maintenance in sustainable agricultural practice as well as the adaptability of the legume microsymbiont to different ecological zones particularly the tropical humid environment.

Key words: Inoculation, Mucuna pruriens, nodulation, organic agriculture, Rhizobium, soil fertility.