Table 3.

The effects of 21 days of drought on chlorophyll fluorescence (PI), photosynthetic CO2 fixation (Pn), leaf chlorophyll content, and necrosis of containerized English oak (Quercus robur L.).^{^z^y}

	PI	Pn	Chlorophyll content	Leaf necrosis	Membrane integrity	Survival (%)
Control	0.18	1.87	30.9	4.1	27.2	20
2 mL (0.06 fl oz) PBZ foliar spray	1.15*	3.38*	38.9*	1.8*	9.8*	100*
4 mL (0.12 fl oz) PBZ foliar spray	2.02*	3.42*	41.1*	2.1*	8.9*	100*
5 mL (0.15 fl oz) PBZ root drench	1.68*	3.52*	48.3*	1.9*	13.2*	100*
10 mL (0.3 fl oz) PBZ root drench	2.41*	3.58*	42.2*	2.0*	9.5*	100*

↵^zMeasurements were made immediately at the cessation of the drought treatment when trees were placed under glasshouse conditions (22°C ± 2°C [71.6°F ± 35.6°F], 16 hr light/8 hr dark photoperiod and minimum 250 μmol/m⁻²/s⁻¹ photosynthetically active radiation at the tree crown.
↵^yPBZ-treated plants: PI and leaf chlorophyll content, values mean of ten trees, five leaves per tree. Pn and electrolyte leakage values mean of ten trees, two leaves per tree. Leaf necrosis values mean of ten trees. Controls: PI and leaf chlorophyll content, values mean of two trees, five leaves per tree. Pn and electrolyte leakage values mean of two trees, two leaves per tree. Leaf necrosis values mean of two trees.
*Significantly different from controls according to least significant difference at P < 0.05; ^ns = not significantly different from control value.
PBZ = paclobutrazol.