Fig. 5

Change of proteinogenic amino acids in leaf and stem base with cuttings of Petunia hybrida in response to graduated nitrogen fertilisation (N_d) to donor plants and dark exposure. Levels: low, high and excess N_d and 168 h dark exposure of cuttings (168 hpe, 10 °C). Panels a to f: Full cycles and open squared symbols connected with full and intermittent lines represent cuttings directly at severance (0 hpe) and after dark exposure, respectively. Total amino acids are given as μmol g⁻¹ FM and single amino acids as nmol g⁻¹ FM, respectively. Multifactorial ANOVA’s revealed significant main and interaction effects for N_d-levels × dark exposure × tissue type p < 0.00001 to p < 0.05 (Panels a, c, d, e, f), for N_d-levels × tissue type p < 0.00001 (Panel b), for dark exposure p < 0.000001 (Panel b). Vertical bars represent 95 % confidence intervals of mean values. Further details are presented in methods and with Additional file 1) Experiments of nitrogen preconditioning of cuttings, Additional file 2) Explanation of experimental designs for statistical analyses and Additional file 3) Supplemental data of figure 5 for Exp. 3: AA-ND, respectively