Figure 1.

Effect of plant growth regulators on the root growth under mechanical stress. (a) effect of a dialysis membrane (as a mechanical barrier) on root growth. One-day-old seedlings were transferred onto dialysis-membrane-covered agar plates that were placed vertically or horizontally (day 0) and grown for 2 days (day 2). The arrowheads indicate the position of the root tip at day 0. Bars, 10 mm. (b) effect of omeprazol (OMP), plant growth regulators, and the related compounds on root growth after transfer to vertically (white bars) and horizontally (gray bars) placed plates, as shown in (a). Each chemical (3 µM OMP, 30 nM naphthaleneacetic acid (NAA), 300 nM ACC, 300 nM MeJA, 1 µM gibberellin A4 (GA4), 1 µM abscisic acid (ABA), 1 nM brassinolide (BL), 100 nM kinetine, 30 µM thermospermine (Tspm), and 10 µM AgNO₃) was supplemented continuously after germination. (c) Ratio of horizontal to vertical root growth shown in (b). (d) effect of different concentrations of ACC and MeJA on the root growth under mechanical stress. (e) ratio of horizontal to vertical root growth shown in (d). In (b) to (e), the error bars represent SD (n > 20). The asterisks indicate statistically significant differences between means, as assessed using Student’s t-test (P < .01).