Table 3.

Cytokinin content in needles of maritime pine plants derived from somatic embryos matured at different temperatures (18, 23, or 28 °C) that were employed in a heat stress experiment for 10 days at 45 °C. Plants were sampled at the beginning of the stress treatment (t0), at the end of the stress treatment (t10), and after a recovery period of a further 10 days (tR). Data are the mean ± SE of six replicates and 22 cytokinins grouped by type: cis-zeatin (cZ), trans-zeatin (tZ), dihydro-zeatin (DZ), and isopentenyladenine (iP). Within each group of plants, values followed by the same letter did not differ significantly (p < 0.05), according to Kruskal-Wallis one-way ANOVA.

Plants	Time	Total iP-Types	Total tZ-Types	Total DZ-Types	Total cZ-Types
M18	t0	0.34 ± 0.04 a	1.45 ± 0.08 a	2.30 ± 0.07 a	2.65 ± 0.16 a
	t10	0.22 ± 0.03 b	0.34 ± 0.05 b	0.86 ± 0.12 ab	0.87 ± 0.08 b
	tR	0.35 ± 0.04 a	0.47 ± 0.05 ab	0.62 ± 0.03 b	1.87 ± 0.04 a
M23	t0	0.26 ± 0.04 b	1.38 ± 0.05 ab	1.56 ± 0.09 ab	2.26 ± 0.06 b
	t10	0.45 ± 0.06 a	0.95 ± 0.11 b	0.87 ± 0.15 b	2.67 ± 0.22 ab
	tR	0.45 ± 0.08 a	2.72 ± 0.52 a	4.12 ± 0.50 a	4.22 ± 0.50 a
M28	t0	0.28 ± 0.06 b	3.73 ± 0.62 a	2.44 ± 0.34 a	6.81 ± 1.14 a
	t10	0.50 ± 0.12 a	0.82 ± 0.05 b	0.64 ± 0.09 b	2.90 ± 0.28 b
	tR	0.28 ± 0.03 b	2.56 ± 0.14 a	2.19 ± 0.16 a	4.60 ± 0.32 ab