Our study showed that the effectiveness of MA and MB Myanmar Bradyrhizobial
isolates to improve growth, N2 fixation and seed yield of soybean
depended on soybean varieties. In Hinthada and SJ5 soybean varieties, MB was
significant better than MA when single inoculation was used. MA was more
effective than MB only in DT84 soybean for improvement shoot dry weight and
N uptake of shoot at R3.5 stage and amount of fixed N throughout the growing
season but not different significantly from MB for the effect on seed yield.
Single inoculation of EA, the selected endophytic actinomycetes did not
have significant effects on all studied parameters in all three tested soybean varieties.
Dual inoculation with EA and MB was not effective compared with single
inoculation of MB and even produced significant depressive effect on amount of
total fixed N for these three soybean varieties. Significant depressive effect of
dual inoculation with EA and MA was found also in DT84 soybean.