Nodule formation, distribution and symbiotic efficacy of Vigna unguiculata L. under different soil salinity regimes

Rhizobium-legume symbiosis is one of the most well-established symbiotic nitrogenfixing system for agronomic studies. The current study aimed to test the hypothesis that screeningfor salt-tolerant rhizobial strains or salt-tolerant cultivar does not necessarily promise a salttolerantsymbiotic system, as the symbiotic system is more sensitive to salt stress than thebacterium and/or the plant. In fact, the current study reveals that there is a decrease in salttolerance of the symbiotic system by 1 dS/m , and also that there is a gradual shift in the spatialdistribution of the nodules from the primary roots to the secondary roots under increased saltlevels, and is time-dependant. Thus, the current study confirms that there is a need to screen forsalt-tolerant symbiotic Rhizobium-legume system for producing efficient root nodules, thereby anefficient repository for nitrogen fixation