Table II.

Inhibitory effect of pH-5.5 buffer on water-induced increases in leaf growth rate and extensibility

Treatment	Growth Rate	Extensibility
		in vivo	in vitro
pH	μm min−1	μm (2 g 3 min)−1
4.5	7  ± 1	22  ± 3	23  ± 3
5.5	3  ± 0	13  ± 2	12  ± 1

Isoosmotic solutions containing 50 mm succinate buffer at pH 4.5 or 5.5 were injected into the leaf-elongation zone as in Figure 1. Growth rate and extensibility were assayed 9 and 12 min after injection, respectively. Results are means ± se, n = 10 for growth rates and n = 5 for the extensibility measurements.