Table I.

pH modifiers alter the pHc of tier 2 and 3 root columella cells of Arabidopsis without affecting root growth

Treatment	pHc	Statistical Significance	Root Growth	Statistical Significance
			μm
Control medium	7.20 ± 0.02		582 ± 72
0.3 μm Bafilomycin A1	7.10 ± 0.04	NS	475 ± 97	NS
1.3 μm Bafilomycin A1	6.75 ± 0.02	S	431 ± 39	NS
100 μm Benzoic Acid	5.52 ± 0.03	S	580 ± 57	NS
50 μm Procaine	7.63 ± 0.08	S	640 ± 66	NS
100 μm Procaine	7.65 ± 0.08	S	540 ± 131	NS
500 μm Methylamine	8.12 ± 0.04	S	466 ± 63	NS

The average pHc from separate roots after a control treatment was 7.20 ± 0.02 (n = 5). Control or pH modifying solutions were applied solely to the root cap. Root growth was measured over 5 h and pHc of the same roots was measured in tier 2 and tier 3 columella cells. Data are means ± se (n = 5 for pHc data, n = 20 for growth data). A t test (95% confidence interval) was used to compare experimental and control values. NS, Not significant.