Fig. 3.

Specific leaf N content of leaf 4 in non-grafted, self-grafted and reciprocally-grafted plants of the winter oilseed rape cultivars NPZ-1 and NPZ-2 (left), and Apex and Capitol (right), grown in hydroponics after 12 d of N starvation (0.1mM N) or optimal N supply (4.0mM N). The plants were pre-cultured for 28 days at 2.0mM N. Different letters on top of the columns indicate differences between the variants (P<0.05). ANOVA: **, *** indicate significant differences at P<0.01 and P<0.001, respectively; ns, non-significant. The error bars represent the standard deviations of the means (n=3–4).