Table 2.
Analysis of variance of the N concentrations, species and organ effects.
| Factor | δ 15N (‰) |
Total Biomass (g DW) |
Total Biomass Ratio (NH4+/NO3- ) |
|||
|---|---|---|---|---|---|---|
| Effect on NO3--fed plants | F | P > F | F | P > F | F | P > F |
| N Conc. | 0.78 | 0.4743 | 38.53 | < 0.0001 | 10.92 | < 0.0001 |
| sp. | 13.20 | < 0.0001 | 80.73 | < 0.0001 | 64.81 | < 0.0001 |
| N Conc. × sp. | 1.18 | 0.3655 | 4.26 | < 0.0001 | 1.43 | 0.1912 |
| Organ | 1.80 | 0.1966 | - | - | - | - |
| Whole model R2 | 0.884 | 0.942 | 0.927 | |||
| Effect on NH4+-fed plants | F | P > F | F | P > F | F | P > F |
| N Conc. | 34.69 | < 0.0001 | 1.57 | 0.2183 | 8.93 | 0.0005 |
| sp. | 17.73 | < 0.0001 | 80.56 | < 0.0001 | 59.10 | < 0.0001 |
| N Conc. × sp. | 0.93 | 0.5418 | 6.84 | < 0.0001 | 1.40 | 0.1999 |
| Organ | 4.76 | 0.0392 | - | - | - | - |
| Whole model R2 | 0.916 | 0.936 | 0.908 | |||
The effects of N concentration and species (sp.) and the corresponding interactions are shown separately by the N source on the isotopic composition (‰), total biomass (g DW) and total biomass ratio (NH4+/NO3--fed plants). The organs did not influence the N concentration interaction (N Conc. × Organ; P > 0.8) or the species interaction (sp. × Organ; P > 0.05) or N Conc. × sp. interaction (N Conc. × Sp. × Organ; P > 0.8) with either N source. The interaction terms, including the organ effects, are therefore not shown above. Significant effects (P ≤ 0.05) are shown in bold text.