IMPROVEMENT OF RHIZOBIAL INOCULANTS OF FABA BEAN IN EGYPTIAN SOILS

Abstract

Faba bean (Vicia faba L.) is a major leguminous crop grown around the world and is most intensively cultivated in the North East Africa. In Egypt, faba bean is considered as one of the most important food legumes and plays a major role in the Egyptian diets. Rhizobium is able to form nitrogen-fixing root nodules as a result of symbiosis with legumes and this permits plant growth in the absence of exogenous N fertilizers. Inoculation of legumes with rhizobia strains selected for high N2-fixing capacity can improve nitrogen fixation in agriculture, particularly when native rhizobia strains are absent from soils or ineffective. Rhizobium-based biofertilizers, available in liquid forms, are commonly used as liquid inoculants and are more suitable for mechanical planting. However, there is a real need for improved formulations of inoculants, to create and commercialize new biofertilizers that will be more effective, more stable over time, of better quality, and meeting farmers' needs. Alternative materials such as polymers are being widely studied to improve the quality and efficiency of rhizobia inoculants and to reduce production costs, as well as their impact on the environment. Rhizobia can show wide variations in numerous characteristics; abiotic and biotic i.e., phage susceptibility stress factors. The presence of rhizobiophages in soils suggests that through selection or elimination of certain types of Rhizobium bacteria, the rhizobiophages influence the evolution of bacterial populations. The present study was devoted to achieve the following main objectives, improve the biofertilizer quality of Rhizobium spp. using alginate formulation and selecting rhizobiophage resistant isolate of Rhizobium.