Abstract: Legumes play a critical role in natural ecosystems, agriculture and agroforestry, where their ability to fix nitrogen in symbiosis makes them excellent colonizers of low-N environments and economic and environmentally friendly crop, pasture and herb species. Few reports exist until now on natural nodulation of legumes. Natural nodulation resource of five pastoral legumes, among which 3 of Loteae (Lotus sp.), 1 Psoraleae (Psoralea sp.) and 1 Trifoleae (Ononis sp.) and prospected from different sites in arid climate of Tunisia, was investigated. Occurency of nodulation and morphology of nodules were observed. Nodulation is reported for the first time on 2 taxas. Three taxas presented globular nodules and two spindle-shaped ones. Nodule shapes are characteristic of legume specie but independent of Rhizobium strain. The color of nodules is not related to that of the roots. It depends much more on the soil quality and color and the presence of the leghemoglobin in nodules. The nitrogen fixation intensity seems very significant for the majority of these species. This characteristic enables them to benefit from symbiosis with rhizobia to resist to the edaphic aridity of soils.
M. Rejili , A. Ferchichi , M. Mahdhi and M. Mars , 2007. Natural Nodulation of Some Wild Legumes in the South Area of Tunisia . Agricultural Journal, 2: 405-411.