FIGURE 1.

High-affinity ${\mathrm{NO}}_{\mathrm{3}}^{\mathrm{–}}$ uptake rate in the roots of maize plants. ¹⁵${\mathrm{NO}}_{\mathrm{3}}^{\mathrm{–}}$ uptake rate by maize plants was measured after different period of treatment (induction) with the anion. At the indicated times, seedlings were transferred to 200 μM ¹⁵${\mathrm{NO}}_{\mathrm{3}}^{\mathrm{–}}$ solution and the ${\mathrm{NO}}_{\mathrm{3}}^{\mathrm{–}}$ uptake was carried out for up to 5 min. Data are the means ± SE; n = 3. The statistical significance was determined by means of Student’s t-test. (^∗∗P < 0.01; ^∗P < 0.05).