Alleviating the Deleterious Effects of Soil Salinity and Alkalinity on Faba Bean (vicia Faba L.) Production Using Rhizobium/Agrobacterium Inoculants

The effectiveness of Rhizobium inoculation is largely determined by soil properties. In this study, the symbiotic efficiency of 17 Rhizobium/Agrobacterium local strains was screened in greenhouse experiments. Subsequently, the combined effects of selected five rhizobial strains plus a starting N-dose (48 kg N ha(-1)) on nodulation and yield of faba bean were evaluated in two-year field trials. The field experiments were conducted in multiple locations which represent fertile, alkaline-calcareous, and salt-affected soils. Regardless of soil type, rhizobial inoculation overwhelmingly improved the nodulation of faba beans compared to the non-inoculated control and N-fertilized (48 and 96 kg N ha(-1)) treatments. In all of the sites, inoculated faba beans, with at least two strains, produced grain yield and grain N yield significantly greater, or comparable to N-fertilized (96 kg N ha(-1)) treatment. The maximum response of faba bean to inoculation was identified in the salt-affected soil, whereas faba bean inoculated with Rlv strain NGB-FR 126 showed significant increases in the averages of grain yield (50%) and grain N-yield (56%) compared to N-fertilized (96 kg N ha(-1)) treatment, over the two cropping seasons. Besides enhancing nodulation, application of rhizobial inoculants effectively improved production and plant response in alkaline-calcareous and salt-affected soil conditions.