Rhizobium Strain Effects on the Growth and Nitrogen Assimilation in Pisum sativum and Vicia faba Plant Growth under Salt Stress

Abstract

Summary The present study was designed to investigate the differences in responses to salt stress between pea (Pisum sativum) and faba bean (Vicia faba) plants inoculated with the same salt-tolerant (GRA19) or saltsensitive (GRL19) Rhizobium leguminosarum strain. After 12 days of growth, the nutrient solution was supplemented progressively with salt until reaching the final concentration (100 mmol/L NaCl) on day 18. This level of NaCl was maintained until harvesting at the beginning of flowering. The growth of pea plants was reduced only in plants inoculated with GRL 19 strain, while the growth of faba bean plants was inhibited regardless of the Rhizobium strain used. Under salt stress, pea plants showed higher levels of nodule mass and nitrogen fixation than faba bean plants. In nodules, nitrogenase and glutamate synthase activities proved more sensitive to salinity than did glutamine synthetase.