Figure 2.

The effect of NPA application at several positions on the Arabidopsis primary root. Five-day-old Arabidopsis seedlings were treated with a line of agar containing 100 μm NPA at several positions along the root. The root was divided into 10-mm zones, with zone 1 beginning at the root-shoot junction. The lines of agar were placed above zone 1, 2, or 3, as indicated. The number and density of lateral roots were determined after 3 d of growth. The data were analyzed by Student's t test, and P values were determined for each sample compared with the controls and are indicated with asterisks (*P ≥ 0.015 and ≤ 0.038; **P ≤ 0.005).