Table 1.

Effect of manipulation of extracellular pH and ROS concentration on Arabidopsis root hair growth

Treatment	Growing, %	Stopping, %	Bursting, %
pH 4.5 (228)	0	0	100
pH 8 (54)	4	96	0
1 μM H2O2 (24)	0	100	0
100 μM ascorbate (104)	16	0	84
10 μM MCLA (100)	2	0	98
25 μM DPI (40)	0	17	83

To determine the effect of extracellular pH and ROS on tip growth, root hairs were selected that exhibited stable growth rates of 1–2 μm min⁻¹ in unbuffered minimal medium. After monitoring root hair growth for ≈10 min, treatment was started by adding compounds/buffers (10 mM DMGA for pH 4.5, 10 mM Hepes for pH 8) listed to the minimal growth medium. Numbers of root hairs are in parentheses.