Table 2.

Comparison of lignin content and cellulose crystallinity index of fibres and sclereids of different Malus accessions determined by Raman spectroscopic analyses in transverse sections of matured peduncles

Species, cultivar	n	Lignin content (%)			Cellulose crystallinity index (%)
		Fibres (mean ± s.d.)	Sclereids (mean ± s.d.)	Test statistics	Fibres (mean ± s.d.)	Sclereids (mean ± s.d.)	Test statistics
Construction type 1:
M. sylvestris	16	19·5 ± 1·1 a	19·1 ± 0·7 ab	P = 0·252, t = 1·2	80·2 ± 6·8 a	59·5 ± 10·9 a	P < 0·001, t = 5·9
M. sieversii ssp. Kirghisorum	32	18·7 ± 1·3 a	19·5 ± 1·0 a	P = 0·008, t = –2·8	68·9 ± 13·9 ab	48·4 ± 10·4 b	P < 0·001, t = 6·8
M. × domestica ‘Pinova'	16	17·8 ± 1·1 ab	18·8 ± 0·8 ab	P = 0·009, t = –2·8	56·8 ± 9·9 bc	42·3 ± 5·0 b	P < 0·001, t = 282·0
M. coronaria	32	18·0 ± 1·8 a	18·7 ± 1·6 b	P = 0·147, t = –1·5	73·8 ± 13·2 ab	60·6 ± 14·6 a	P = 0·005, t = 638·0
Construction type 2:
M. baccata	32	11·1 ± 1·9 c			36·6 ± 3·7 d
M. fusca	32	14·1 ± 2·1 bc			48·5 ± 12·1 c

n, sample size. Data are from four measurements (at 2–4 single cells) at four different regions in transverse sections of two peduncles of each species, respectively; only one sample for both M. sylvestris and the cultivar ‘Pinova’. Test statistics: t-test, Mann–Whitney rank sum test, P values indicating statistical differences between values of fibres and sclereids. Values in a column with the same letter are not statistically different (for the lignin content of sclereids: one-way ANOVA F_3,94 = 3·3, P = 0·025 followed by an all-pairwise multiple comparison procedure Tukey test, P < 0·05; other parameters Kruskal–Wallis one-way ANOVA on ranks followed by an all-pairwise multiple comparison procedure Dunn's method, P < 0·05; for the lignin content of fibres: H_5,155 = 109·9, P ≤ 0·001; for the cellulose crystallinity index of fibres: H_5,143 = 95·2, P ≤ 0·001; for the cellulose crystallinity index of sclereids: H_3,94 = 33·3, P ≤ 0·001).