The Effect of Salinity on Nitrogen Fixation in Rhizobium and Soybean Symbiosis System

This experiment was conducted to investigate the effect of salinity on nitrogen fixation in Rhizobia and soybean symbiosis system. Soil and water salinity are the most important factors to decrease of agricultural productions in arid and semi-arid regions. Also nitrogen is one of the macro elements that plants need to growth. Biological fertilizers can use instead of chemical fertilizers for nitrogen fixation. In order to study of salinity effect on the dry matter production for both above ground portions and the roots and also percentage of the plant uptake Nitrogen، a greenhouse experiment was conducted. Greenhouse experiment was done in a completely randomized factorial block design. 4 treatments (blank، Nitrogen، granular inoculant using and powder inoculant using) 3 levels of salinity (EC=0، 4، 8 ds/m) with 4 replications were used. After 90 days، in order to dry matter measurement، above ground portions and roots were cut and put in 110ͦc oven for 48 hours. The data were analyzed by SAS software for statistical evaluations. Results showed that the amounts of dry matter production for both above ground portions and the roots and also the plant nitrogen uptake percentage were shown significant difference between salinity treatments. In EC=0 ds/m، the powder form treatment was shown the highest nitrogen uptake percentage، then granular inoculant، nitrogen treatment and blank respectively. However in EC=4، 8 ds/m the granular form treatment was shown the highest nitrogen uptake percentage، then powder form inoculant، nitrogen treatment and blank respectively.