. Author manuscript; available in PMC: 2018 Jan 18.

Published in final edited form as: Plant Cell Environ. 2014 Oct 7;38(4):751–766. doi: 10.1111/pce.12435

Table 1.

Leaf structural characteristics and pigment contents (mean ± SE) in hybrid aspen (P. tremula x P. tremuloides, clone H200) grown at contrasting temperatures

Characteristic	Growth temperature (day/night)

	25/20 ºC	35/27 ºC
Leaf area (cm²)	67.5 ± 2.4a	82.3 ± 2.7b
Leaf dry mass per unit area (g m^-2)	47.6 ± 1.7a	30.5 ± 1.1b
Leaf thickness (μm)	133.9 ± 3.3a	93.5 ± 2.8b
Palisade mesophyll thickness (μm)	71.5 ± 3.1a	40.9 ± 2.6b
Spongy mesophyll thickness (μm)	44.3 ± 1.0a	34.4 ± 0.8b
Chloroplast number per cm² leaf area (palisade)	(38.8 ± 2.2).10⁶a	(29.3 ± 1.9).10⁶a
Chloroplast number per cm² leaf area (spongy)	(7.5 ± 0.5).10⁶a	(7.1 ± 0.3).10⁶a
Total chloroplast number per cm² leaf area (palisade+spongy)	(46.3 ± 3.7).10⁶a	(36.4 ± 2.3).10⁶a
Chloroplast length (μm)	4.41 ± 0.17a	4.14 ± 0.18a
Chloroplast width (μm)	1.99 ± 0.09a	1.52 ± 0.11b
Chloroplast area (μm²)	7.23 ± 0.49a	4.99 ± 0.51b
Starch grain area per chloroplast (μm²)	1.05 ± 0.11a	0.047 ± 0.11b
Chlorophyll content per area (mg m^-2)	413 ± 16a	302 ± 12b
Chlorophyll content per dry mass (mg g^-1)	9.11 ± 0.27a	9.20 ± 0.29a
Chl a/b ratio	2.68 ± 0.11b	2.38 ± 0.08b
Carotenoid content (mg m^-2)	88.4 ± 2.9a	58.9 ± 2.2b
Carotenoid content per dry mass (mg g^-1)	1.80 ± 0.05a	1.90 ± 0.05a

Means with the same letter are not statistically different (P > 0.05 according to ANOVA, n = 6, for leaf structural measurements and pigment contents and n = 30-42 for leaf anatomical measurements)