Effects of storage temperature, duration and inoculation methods on Bradyrhizobium japonicum growth with soybean

The positive effect of root-nodulating strains of Bradyrhizobium spp in soybean in terms of biological nitrogen fixation and plant growth and development is still a main focus in the present. According to the literature, a concentration of 105 -106 bacteria on the seed, will guarantees that the root can be infected during the germination process, and in this way will achieve early nodulation. In this research the effects of storage temperature, duration and inoculation methods on the survival of Bradyrhizobium japonicum growth on soybean seeds and the performance of soybean bacterial inoculant on seeds under field conditions were determinate. The results showed that the storage of the inoculated seeds at low temperature (5-10°C) can assure a very good root infection in order to obtain a higher nodule number and after 90 days, whether the inoculation was done in station or factory. The registered results showed values which ranged from 0.03*105 to 5.06*105 CFU/seed. In case of the performance of soybean bradyrhizobia inoculants on seeds under field conditions we determined that from the soybean tap roots, the highest number of nodules was 138, while the lowest number was 42 nodules. Regarding the total weight of the nodules prevailed from the tap roots, the highest registered values was 4748.0 mg. In case of secondary roots, the highest number of nodules was 353, while the lowest number was 103