Stress Factors Affecting Symbiosis Activity and Nitrogen Fixation by Rhizobium Cultured in vitro

Abstract

Rhizobium (family Rhizobiaceae ) is a group of symbiotic bacteria which fix atmospheric nitrogen throughout nodule formations, can be found in soil or in roots of legumes. This process transforms atmospheric nitrogen to ammonia, nitrate and nitrogen dioxide. Within the soil, rhizobia frequently encounter various stresses that affect their growth, their initial steps of symbiosis and the capability of nitrogen fixation. Biological nitrogen fixation is a critical and key process in sustainable land management, nitrogen being the nutrient that limits crop production in a high level. Biotic and abiotic stresses impose a major threat to agriculture and symbiotic nitrogen fixation is dependent on host cultivar and rhizobia, but as well may be limited by pedoclimatic factors. The most common factors affecting nitrogen fixation and symbiosis activity are salinity, drought and temperature