Table 1.

Basal (nonstressed) alterations to plant physiology of English oak (Quercus robur L.) at week 2 after paclobutrazol (PBZ) application.^{^z^y}

Parameter	Control	2 mL (0.06 fl oz) PBZ foliar spray	4 mL (0.12 fl oz) PBZ foliar spray	5 mL (0.15 fl oz) PBZ root drench	10 mL (0.3 fl oz) PBZ root drench	Percent change by PBZ
Membrane integrity	2.23	1.79^*	1.89^*	1.70^*	1.67^*	−17.9--33.5
PI	5.81	6.89^*	5.99^ns	7.00^*	6.17^*	+3.3–17.0
Pn	4.87	5.11^*	5.02^ns	5.15^*	5.00^ns	+2.6–5.4
Carotenoids (lutein: β-carotene:neoxanthin:α-carotene)	4.13 (58:17:21:4)	5.28^* (59:16:22:3)	4.40^* (61:15:22:2)	5.63^* (56:19:20:5)	4.48^* (60:17:20:3)	+14.9–21.8
Xanthophylls (zeaxanthin:antheraxanthin:violaxanthin)	3.18 (45:17:38)	3.47^ns (43:18:39)	3.45^ns (46:15:39)	4.50^* (42:18:40)	4.07^* (44:18:38)	+15.5–23.3
Total carotenoids (x + c)	7.31	9.11^*	7.85^*	10.13^*	8.55^*	+17.2–22.3
Proline	117.1	140.4^*	139.0^*	145.0^*	154.3^*	+15.7–24.1
SOD	213.4	245.4^*	222.7^ns	239.7^*	251.4^*	+4.2–15.1
Catalase	845.6	1000.2^*	934.6^*	1228.9^*	1177.8^*	+9.5–31.2
Leaf necrosis	0.1	0.4^*	0.0^ns	0.0^ns	0.0^ns	0-+75
Chlorophyll a/b	2.97	3.01^ns	3.00^ns	2.89^ns	3.05^ns	−2.7-+2.6
Total chlorophylls	82.1	101.3^*	93.5^*	112.5^*	98.3^*	+12.1–27.0

↵^zTrees 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).
↵^yMembrane integrity, PI, chlorophylls, carotenoids, xanthophylls, leaf proline, SOD, catalase, and leaf necrosis values mean of ten trees. Membrane integrity (percent electrolyte leakage), leaf chlorophylls, carotenoids, and xanthophylls content μg/g fresh leaf weight), leaf proline μg/g dry leaf weight), SOD (units g fresh leaf weight), catalase μmol/min⁻¹ g fresh leaf weight).
↵*Significantly different from controls according to least significant difference at P < 0.05; ^ns = not significantly different from control value.
PI = photosynthetic efficiency; Pn = light-induced CO2 fixation; SOD = superoxide dismutase.