Figure 2.

Temporal course of H₂O₂ and O₂⁻ concentration in the youngest fully expanded young leaves of two barley cultivars (Milford, M; Sahin-91, S91) grown in the nutrient solution under two levels of K supply (adequate K: 0.8 mM K⁺; low K 0.04 mM K⁺) without and with a PEG-induced water deficit (−PEG; +PEG) 5–25 days after the onset of K treatments (DAO). The letters (a–f) represent each single combination of K-level × PEG-level × barley-variety. On each sampling day, values of the treatments “low K −PEG”, “adequate K +PEG” and “low K +PEG” are expressed as fold changes in comparison to control (“adequate K −PEG” = 100%, represented by the solid horizontal line in each plot). Symbols represent means ± SE (n = 6). Significant differences of the measurements are provided in the appendix (Table A1).