Effect of salt stress on interaction between lentil (Lens culinaris) genotypes and Rhizobium spp. strains: symbiotic N-2 fixation in normal and sodicsoils

Following screening, selection, characterization and examination of their s ymbiotic Nz fixation, only two Rhizobium strains (ND-16 and TAL-1860) and f our lentil genotypes (DLG-103, LC-50, LC-53 and Sehore 74-3) were found to be suited to sodic soils. Interactions between salt-tolerant lentil genotyp es and Rhizobium strains were found to be significant, and resulted in grea ter nodulation, Nz fixation (nitrogenase activity), total nitrogen, plant h eight, root length and grain yield in sodic soils under field conditions co mpared to uninoculated controls. Significantly more nodulation, nitrogenase activity, glutamine synthetase (GS) and NADH-dependent glutamate synthase (NADH-GOGAT) activities were found in normal soil as compared to the soil s upplemented with 4% and 8% NaCl. Salt stress inhibited nitrogenase, GS and NADH-GOGAT activities. However, nitrogenase activity in nodules was more se nsitive to salt stress than GS and NADH-GOGAT activities (NH4+ assimilation ). The relevance of these findings for salt-tolerant symbionts is discussed .