Table 4.
Impacts of N, P, and Mg combinations on colonization densities of Bradyrhizobium japonicum and on the growth of soybean seedlings in a gnotobiotic sand-vermiculite system.
| Treatments* | Root lengtha | Shoot heighta | Fresh weightb | Dry weightb | 104CFU/cm root |
|---|---|---|---|---|---|
| HNHP | 13.5 ± 1.00bcd | 20.0 ± 1.82a | 1.14 ± 0.12ab | 0.14 ± 0.04ab | 2.62 ± 0.56cd |
| HNHMg | 16.0 ± 1.50ab | 15.5 ± 1.00b | 1.31 ± 0.23ab | 0.19 ± 0.08a | 6.78 ± 0.78a |
| HNLP | 14.5 ± 1.71bcd | 17.5 ± 1.29b | 1.26 ± 0.15a | 0.13 ± 0.01ab | 3.05 ± 0.49c |
| HNLMg | 16.2 ± 0.95a | 20.5 ± 1.804 | 1.30 ± 0.23a | 0.13 ± 0.03ab | 4.72 ± 0.73b |
| LNHP | 13.2 ± 1.50bcd | 18.5 ± 0.57ab | 1.12 ± 0.16ab | 0.09 ± 0.03b | 2.01 ± 0.30e |
| LNHMg | 15.5 ± 1.00abc | 20.0 ± 1.29a | 1.12 ± 0.08ab | 0.13 ± 0.05ab | 4.10 ± 0.59b |
| LNLP | 13.0 ± 1.71cd | 16.0 ± 0.50b | 0.95 ± 0.14b | 0.09 ± 0.02b | 1.89 ± 0.31e |
| LNLMg | 11.7 ± 1.00d | 17.2 ± 0.45b | 1.36 ± 0.18a | 0.11 ± 0.01b | 1.84 ± 0.25e |
Plants were grown for 12 days;
a
cm,
b
g/plant; Different letters indicate significant differences between treatments at P < 0.05 (Tukey's t-test).
*
high N and high P (HNHP), high N and high Mg (HNHMg), high N and low P (HNLP), high N and low Mg (HNLMg), low N and high P (LNHP), low N and high Mg (LNHMg), low N and low P (LNLP), and low N and low Mg (LNLMg). Columns represent means for six plants (N = 6) with standard error bars, and different letters indicate significant differences between treatments at P < 0.05 (Tukey's t-test).