TABLE 1.
Plant parametersa
| Parameter | Nonamended soil (mean ± SD)
|
Leaf litter-amended soilb (mean ± SD)
|
Effects of leaf litter amendment and inoculation (P)c
|
|||
|---|---|---|---|---|---|---|
| Noninoculatedd | Inoculatede | Noninoculatedd | Inoculatede | Inoculation | Leaf litter | |
| Plant height (cm) | 26 ± 7 | 30 ± 9 | 36 ± 10 | 38 ± 7 | 0.181 | <0.001 |
| Plant weight (g [dry wt.]) | 2.9 ± 1.3 | 4.1 ± 2.5 | 4.3 ± 1.7 | 5.6 ± 1.6 | 0.028 | 0.004 |
| C/N ratio of leaves | 15 ± 1.4 | 16 ± 1.3 | 14 ± 1.4 | 16 ± 1.4 | 0.003 | 0.836 |
| Atom% excess 15N values of leaves | 1.1 ± 0.6 | 0.9 ± 0.9 | 0.7 ± 0.3 | 0.6 ± 0.5 | 0.022 | 0.445 |
| Atom% excess 15N values of stems | 1.6 ± 0.8 | 1.2 ± 0.8 | 1.1 ± 0.5 | 0.8 ± 0.6 | 0.178 | 0.016 |
| Atom% excess 15N values of roots | 2.0 ± 1.0 | 1.4 ± 0.8 | 1.3 ± 0.7 | 1.3 ± 0.9 | 0.129 | 0.018 |
| Plant uptake of soil nitrogen (%) | 6.1 ± 2.2 | 5.9 ± 3.7 | 6.0 ± 4.0 | 7.1 ± 4.7 | 0.494 | 0.455 |
| Amount of fixed nitrogen in plants (%) | 33 ± 19 | 53 ± 34 | 58 ± 25 | 78 ± 24 | 0.008 | 0.002 |
| δ13C values of leaves (‰) | −30.5 ± 0.8 | −29.7 ± 1.6 | −29.8 ± 0.8 | −29.2 ± 1.1 | 0.075 | 0.016 |
| δ13C values of roots (‰) | −30.3 ± 0.7 | −29.5 ± 1.8 | −29.3 ± 1.2 | −28.7 ± 1.3 | 0.225 | 0.014 |
a
The averaged parameters (± standard deviation) were obtained after 4 months of growth.
b
Soil “Ettiswil” mixed with dried alder leaves to a final concentration of 1%.
c
Statistical analysis was performed using two-way ANOVA, and corresponding P values are shown.
d
Soil “Ettiswil.”
e
Soil “Ettiswil” inoculated with Frankia strains ArI3, Ag45/Mut15, and AgB1.9, each at a density of 107 cells g of soil−1 (fresh wt.).