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Table 2 Analysis of variance of the N concentrations, species and organ effects.

From: Depletion of the heaviest stable N isotope is associated with NH4+/NH3 toxicity in NH4+-fed plants

Factor δ 15N
(‰)
Total Biomass
(g DW)
Total Biomass Ratio
(NH4+/NO3- )
Effect on NO 3 - -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 NH 4 + -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
  1. 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.