FIGURE 7.

(A) Part of the Plexiglas holder, viewed from above, which was used to pretreat the apical 0–3 mm region of the primary root of line FR697 with the H₂O₂ scavenger KI. The holder contained a 5-mm thick layer of 1% agarose gel, with or without KI, into which the root tip was inserted. Because the roots elongated during the pretreatment, the kernels were moved away from the gel every 2 h such that only the apical 3 mm of the roots were embedded in the gel. After 6 h, the seedlings were transplanted to well-watered or water-stressed conditions. (B) Elongation rates of control and KI-pretreated (30 or 45 mM) primary roots after transplanting to well-watered (WW) or water-stressed (WS; –1.6 MPa) conditions. The elongation rates are plotted at the midpoint between marking intervals, which were at 0, 16, 24, 40, and 48 h after transplanting. Data are means ± SE of three independent experiments (n = 15–40 seedlings per treatment in each experiment). Different letters denote significant differences between treatments at specific times within each condition (t-test; P < 0.05).