Figure 5

Light- (A) and pH-dependency (B) of the net nitrate-uptake by leaf discs. N-deprived cucumber plants were treated with 4 mM nitrate for 12 h. Plants were exposed to dark, low (100 μmol m^-2 h^-1) or high (500 μmol m^-2 h^-1) light for 8 h before collecting leaf discs. The pH dependency was evaluated using 10 mM MES-NaOH buffer (pH 5.0, 5.5, 6.0 or 6.5) or 10 mM Hepes-NaOH (pH 7.5). Data are means ± SD of three experiments with four replicates.