Figure 1

Net nitrate-uptake rate by cucumber roots (A) and leaf discs (B). Cucumber plants were grown in N-free nutrient solution for 5 days before being exposed to 4 mM nitrate. Uptake by roots was measured at 0.2 mM nitrate, while by leaves either at 0.2 (inside) or 2 mM nitrate. Data are means ± SD of three experiments with four replicates.