Studies on nodulation of soyabean in Egypt. I. Selection of an efficient strain of Rhizobium japonicum.

Both pot (sterilized sand cultures) and field experiments were run, using 23 different strains of Rhizobium japonicum and the commercial soyabean inoculum "Okadin". The failure of the control (non-inoculated plants) to form nodules may be due to the abscence of adequate densities of effective soyabean-rhizobia strains and their low persistence under Egyptian soil conditions. Therefore, inoculation with an efficient strain of R. japonicum seemed to be necessary. However, the strains used varied in their effectiveness, indicating that both the total number of nodules and total nitrogen content of the nodules should not be taken as an index.