In DT84 soybean variety, MA was more effective than MB at R3.5 stageeven though MB performed better (P<0.05) at V6 stage for improvement of shootdry weight (56% over that of the uninoculated control). Nevertheless, noduledry weight of MB inoculated soybean plants at V6 and R3.5 growth stages wereabout 84 and 48 % higher than that of uninoculated control while those fromMA inoculated ones were about 28 and 60%. At R3.5 stage, shoot dry weightof soybean plants from inoculated treatments were about 16-69% over that fromuninoculated treatment however only the effects of single inoculation with MAwas significant (Table 3). Not only shoot dry weight, MA was significantly more effective than MBfor the effects on shoot N uptake at R3.5 stage. Single inoculation with MAresulted in improvement of 287% shoot N uptake while that of single inoculationwith MB increased about 112% compared to uninoculated control. In DT84soybean, single inoculation with EA did not show significant effect on all studiedparameters. Dual inoculation of EA and the tested bradyrhizobial isolates produceddepressive effect compared with single inoculation of each Bradyrhizobial isolate.Such depressive effects of dual inoculation on shoot dry weight, shoot N uptakeand amount of total fixed N were clearly observed in EA+MA treatment whilethat of EA+MB was shown on the amount of total fixed N.Regarding to N2 fixing of DT84 soybean, it was found both MA and MBwere effective to improve N2 fixation significantly. In uninoculated control plant,only 52% of N in the plant derived from N2 fixation while those from MA andMB inoculated plants were more than 93%.Though MA and MB were significantly different from the ability to improveshoot dry weight and shoot N uptake at R3.5 and the amount of total fixed N inDT84 soybean but these two Bradyrhizobial isolates did not differ significantlyfor the effect on seed yield. DT84 soybean seed yield increased about 55 and45% over that of uninoculated control by significant inoculation of MA and MBrespectively. Single inoculation of EA resulted in only 19% improvement and thedifference of seed yield between EA and the control was not significant.In Hinthada soybean, though the tested treatments affect significantlynodule dry weight, root dry weight, shoot dry weight at both V6 and R3.5 stage,measured N2 fixing parameter at R3.5 stage (RUI) and calculated percentageof fixed N (%P) (data not shown) but in this Myanmar soybean the significantcorrelations between RUI and the following parameters, nodule dry weight andshoot N uptake at R3.5 stage and seed yield were found. Furthermore, correlationbetween root dry weight and shoot N uptake of this soybean variety at R3.5 wasalso significantly (Table 4).In SJ5 soybean, the studied treatments did not have significant effects onnodulation and N2 fixing parameters but RUI correlated significantly with yield.Significant correlation between root nodule dry weight and shoot N uptake atR3.5 stage was also observed (Table 5).In DT84 soybean variety, significant correlation between RUI and thefollowing parameters, nodule, root and shoot dry weight and shoot N uptakeat R3.5 stage and seed yield (Table 3). Nodule dry weight at R3.5 stage wascorrelated significantly also with shoot N uptake (Table 4).
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