Figure 4.

¹⁵NO₃⁻ influx in Arabidopsis and Thellungiella roots. Seedlings were grown on vertical plates with nutrient solution containing 4 mm (A), 1 mm (B), and 0.4 mm (C) nitrate for 10 and 12 d, respectively, and then transferred to nutrient solution containing the indicated concentrations of ¹⁵NO₃⁻ (99% atom excess ¹⁵N) for 5 min. Data are means ± sd (n = 5), and each replicate consisted of a pool of 15 to 20 plants. Fisher's protected lsd test showed a significant difference (P < 0.05) at 0.4 and 0.2 mm ¹⁵NO₃⁻ between Arabidopsis and Thellungiella.