Nodulation and nitrogen fixation of some wild legumes from differing habitats in Egypt

This study was devoted to exploring the natural nodulation and nitrogen fixation of wild legumes grown in different Egyptian habitats. These habitats are representative to four phytogeographical regions. Sites that inhabited by Melilotus indicus, Medicago polymorpha, Trifolium resupinatum, Trigonella hamosa and Vicia sativa in each region were selected for study. High nodulation, nitrogen fixation and plant biomass were recorded in plants grown at Nile region and Oases compared with those at Mediterranean region and Sinai. The inhibition in nodulation and potential of nitrogen fixation in legumes at MR and S were attributed to drought and low soil fertility. Differences in species, regions or their interaction have significant effect on nodulation, legheamoglobin, nitroginase activity and biomass of nodules, shoots and roots; the magnitude of effect due to different species was the greatest. Five rhizobial isolates ( Sinorhizobium fredii , Rhizobium mesosinicum, Rhizobium daejeonense, Rhizobium huautlense, Rhizobium alamii ) recovered from root nodules of the five species were identified by 16S rRNA gene sequence. The indigenous rhizobia of legumes grown at MR and S expected to be exhibit higher tolerance to the existing harsh environmental conditions. These rhizobia can be used as inoculants for crop legumes under unfavorable environmental conditions of agroecosystems or recently reclaimed desert.