Table 1.
Effects of different NaCl levels on the growth of the four tested Bradyrhizobium strains.
| Strains | Replicates | NaCl (M) | ||||||
|---|---|---|---|---|---|---|---|---|
| CK | 0.1 | 0.2 | 0.3 | 0.35 | 0.4 | 0.5 | ||
| RJS9-2 | I | ++++ | ++++ | ++++ | ++++ | +++ | + | + |
| II | ++++ | ++++ | ++++ | +++ | +++ | ++ | − | |
| III | ++++ | ++++ | ++++ | +++ | +++ | + | − | |
| IV | ++++ | ++++ | ++++ | +++ | +++ | ++ | + | |
| BS1-1 | I | ++++ | + | + | − | − | − | − |
| II | ++++ | + | − | + | − | − | − | |
| III | ++++ | ++ | + | − | − | − | − | |
| IV | ++++ | ++ | + | − | − | − | − | |
| PN13-3 | I | ++++ | + | + | − | − | − | − |
| II | ++++ | + | ++ | − | − | − | − | |
| III | ++++ | + | + | − | − | − | − | |
| IV | ++++ | ++ | + | − | − | − | − | |
| LZ3-2 | I | ++++ | + | − | − | − | − | − |
| II | ++++ | + | + | − | − | − | − | |
| III | ++++ | + | − | − | − | − | − | |
| IV | ++++ | + | + | − | − | − | − | |
The four tested strains were separately inoculated onto solid medium supplied with 0.0017, 0.1, 0.2, 0.3, 0.35, 0.4, or 0.5 M NaCl. Among the different NaCl concentrations, 0.0017 M NaCl was set as the control (CK). All of the plates were incubated in an incubator at 28 °C in the dark. The growth of the four tested strains was recorded after 6 days of NaCl treatment. ++++: No inhibition by salt stress. +++: 30% growth inhibition by salt stress. ++: 60% growth inhibition by salt stress. +: 90% growth inhibition by salt stress. −: No growth under salt stress.