A. MOSTAJERAN1, G. EMITAZI1 AND M. MAHMOODY
Abstract
In order to study the physico-chemical parameters of the soil and its effect on the growth and distribution of Rhizobium, a novel method has been used to enumerate Rhizobium with the use of plant infection as a complementry test. Although, the results indicated that the percentages of organic compounds and nitrogen, along with the soil density and pH have a significant effect on the number of Rhizobium, but the percentage of clay and the electrical conductivity did not have any effect on the number of this bacteria found in the soil. The number of nodules per plant indicates that some of the soil physico-chemical parameters such as bulk density, organic matter, nitrogen content have significantly effect on the degree of nodulation, while clay content and acidity of soil had no effect on nodule formation. The degree of nodulation with respect to the number of Rhizobium in the soii.shows that there was a correlation between the number of Rhizobium and the degree of nodulation. To evaluate the resistance of Rhizobium strains isolated from alfalfa in different locations to salinity, they were grown in vitro under different concentration of sodium chloride. According to statistical analysis the Naein strains are more resistant to salinity. However Ardestan strains have more significant effect on the growth of alfalfa.