Response of Vigna Unguiculata Grown Under Different Soil Moisture Regimes to the Dual Inoculation with Nitrogen-Fixing Bacteria and Arbuscular Mycorrhizal Fungi

The interaction between legumes, rhizobial and arbuscular mycorrhizal (AM) partners benefits plant nutrition and improves plant tolerance to water stress. The present research evaluated the effectiveness of symbioses between cowpea plants (Vigna unguiculata (L.) Walp.), AM fungi (Glomus intraradices) and two strains of Bradyrhizobium japonicum on the mycorrhization, acid phosphatase activity (APase), enzymes related to nitrogen fixation and assimilation, and biomass accumulation at three soil moisture levels. The results revealed that the soil moisture optimal for the formation of active symbiotrophic associations in cowpea cultivation was about 60% water-holding capacity (WHC), where both Bradyrhizobium strains and AM fungi function well with respect to mycorrhization, nitrogen and phosphorus uptake, nitrogen fixation and plant biomass production. Under conditions of reduced water supply, the symbiotic association between Br. japonicum-273 and Gl. intraradices was better for cowpea cultivation, while in elevated soil moisture association between Br. japonicum-269 and Gl. intraradices was more appropriate.