Table 1.

Total sugar release for the top three performing Populus samples at each pretreatment condition tested (indicated by asterisk), with their performance and relative rankings listed for the other conditions applied

Rank	Sample ID	Sugar release (g/g) and rank (number) for the other pretreatments				Lignin content (%)	S/G ratio (−)	dbh (cm)
		180 °C	160 °C	140 °C	No pretreatment
180 °C
1	273	0.672 ± 0.014*	0.608 ± 0.006 (4)	0.550 ± 0.010 (6)	0.060 ± 0.030 (32)	22.42	2.0	23
2	909	0.667 ± 0.030*	0.675 ± 0.010 (2)	0.568 ± 0.012 (2)	0.224 ± 0.007 (5)	22.57	2.0	24
3	349	0.654 ± 0.015*	0.606 ± 0.033 (5)	0.551 ± 0.008 (5)	0.074 ± 0.049 (25)	22.48	2.0	14
160 °C
1	833	0.600 ± 0.015 (23)	0.682 ± 0.007*	0.498 ± 0.010 (12)	0.169 ± 0.015 (8)	21.81	2.0	26
2	909	0.667 ± 0.030 (2)	0.675 ± 0.010*	0.568 ± 0.012 (2)	0.224 ± 0.007 (5)	22.57	2.0	24
3	819	0.634 ± 0.004 (7)	0.622 ± 0.014*	0.580 ± 0.019 (1)	0.258 ± 0.002 (4)	17.83	1.7	49
140 °C
1	819	0.634 ± 0.004 (7)	0.622 ± 0.014 (3)	0.580 ± 0.019*	0.258 ± 0.002 (4)	17.83	1.7	49
2	909	0.667 ± 0.030 (2)	0.675 ± 0.010 (2)	0.568 ± 0.012*	0.224 ± 0.007 (5)	22.57	2.3	24
3	152	0.644 ± 0.002 (5)	0.590 ± 0.054 (9)	0.564 ± 0.005*	0.05 ± 0.020 (34)	22.5	1.7	38
No pretreatment
1	876	0.601 ± 0.009 (22)	0.576 ± 0.005 (10)	0.553 ± 0.009 (4)	0.376 ± 0.011*	15.74	1.9	8
2	081	0.606 ± 0.021 (19)	0.575 ± 0.030 (11)	0.533 ± 0.021 (8)	0.336 ± 0.020*	17.06	1.8	16
3	869	0.534 ± 0.008 (32)	0.483 ± 0.030 (31)	0.430 ± 0.017 (24)	0.283 ± 0.013*	17.30	1.3	92

Shown are the mean values from three replicates for all pretreatment conditions and two replicates for just enzymatic hydrolysis together with SEMs. The sugar releases are reported in grams sugars per grams raw biomass. dbh, diameter on breast height (i.e., the diameter of the sampled tree).