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Fig. 1. Introduction to Handeliodendron bodinieri, including H.bodinier (A); Leaf (B); Stamen (C); Pistil (D); Capsule (E); Seeds (F). A–E photo provided by Peng Jian.

Fig. 2. Distribution of Handeliodendron bodinieri, including Funing in Yunnan province; Xingyi, Anlong, Dushan, Pingtang, Libo, Sandu, Duyun in Guizhou province; Longlin, Tianlin, Leye, Lingyun, Tiandong, Longzhou, Tian’e, Fengshan, Nandan, Donglan, Huanjiang, Bama in Guangxi province.

Table 1. Osmotic adjustment of 15 kinds of PEG (molecular weight, 6000) for Handeliodendron bodinieri seeds. Seeds with a moisture content of 4.77% were soaked for 2, 4, or 6 days in 5%, 10%, 15%, 20%, or 25% PEG solutions in Petri dishes. Thus, the test comprised 15 treatments, including all possible combinations of PEG concentration and storage times.
serial number combination serial number combination serial number combination
1 5%PEG 2d 6 5%PEG 4d 11 5%PEG 6d
2 10%PEG 2d 7 10%PEG 4d 12 10%PEG 6d
3 15%PEG 2d 8 15%PEG 4d 13 15%PEG 6d
4 20%PEG 2d 9 20%PEG 4d 14 20%PEG 6d
5 25%PEG 2d 10 25%PEG 4d 15 25%PEG 6d
PEG = polyethylene glycol.
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Fig. 3. Physiological analysis of Handeliodendron bodinieri seeds after ultra-dry treatment with different moisture content in 4 ℃ and room temperature. Storage at room temperature, the MDA (p < 0.05) content and relative conductivity (p < 0.05) increased slowly as the storage time increased, whereas soluble sugar (p < 0.05) and soluble protein (p < 0.05) contents and SOD (p < 0.05) and POD (p < 0.05) activities first decreased and then increased. stored at 4 °C, the relative conductivity (p < 0.05) increased obviously as the MC decreased, and the soluble sugar (p < 0.05) and soluble protein (p < 0.05) contents (p < 0.05), SOD (p < 0.05) and POD (p < 0.05) activities, and MDA (p < 0.05) content varied at different time points. View larger in new window/tab.

Table 2. Means and standard errors of germination characteristics of Handeliodendron bodinieri seeds at room temperature and 4 ℃ after storage for 160 days. Germination characteristics of seeds (CK) with a moisture content of 9.62 not recorded are indicated as “n.d.”
Moisture
content (%) 		Germination proportion (%) Germination potential (%) Germination index Vigor index
room temperature
2.54% 70.45 ± 1.36d 70.45 ± 1.36d 3.00 ± 0.18d 1.15 ± 0.10c
3.14% 80.95 ± 2.00b 80.95 ± 2.00b 3.26 ± 0.07c 1.35 ± 0.03b
3.97% 83.33 ± 1.38b 83.33 ± 1.38b 3.72 ± 0.17b 1.31 ± 0.02b
4.77% 92.50 ± 2.5a 92.50 ± 2.5a 4.53 ± 0.13a 1.93 ± 0.09a
9.62% (CK) 77.27 ± 2.00c 36.36 ± 2.10d 1.94 ± 0.14e 0.66 ± 0.03d
p-value <0.001 <0.001 <0.001 <0.001
4 ℃
2.54% 68.18 ± 2.09c 22.73 ± 1.55b 2.12 ± 0.08a 0.76 ± 0.11ab
3.14% 73.81 ± 1.91b 19.05 ± 0.76c 1.84 ± 0.04b 0.68 ± 0.03b
3.97% 81.82 ± 2.00a 27.27 ± 0.91a 2.16 ± 0.10a 0.83 ± 0.01a
4.77% 54.76 ± 2.86d 16.67 ± 2.38c 1.09 ± 0.13c 0.37 ± 0.07c
9.62% (CK) n.d. n.d. n.d. n.d.
p-value <0.001 <0.001 <0.001 <0.001
Different lowercase letters showed significantly difference at p < 0.05. CK = control check.
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Fig. 4. Physiological index PCA factor of Handeliodendron bodinieri seeds after ultra-dry treatment with room temperature(A) and 4 ℃(B). In plot A, factor 1 accounted for 45.1% of the variance, factor 2 accounted for 23.9% In plot B, factor 1 accounted for 49.1% of the variance, factor 2 accounted for 26.5%. SOD = superoxide dismutase, POD = peroxidase activity, MDA = malondialdehyde, SS = soluble sugar, SP = soluble protein, RC = relative conductivity, GR = germination rate, GP = germination potential, GI = germination index, VI = vitality index. View larger in new window/tab.

Table 3. Means and standard errors of germination percentage and germination index changes of different priming for Handeliodendron bodinieri seeds in ultra-dry storage.
serial number treatment germination
(%) 		germination index (GI)
1 5%PEG 2d 83 ± 2.65bcd 3.71 ± 0.25c
2 10%PEG 2d 84 ± 2 bc 3.80 ± 0.19c
3 15%PEG 2d 82.67 ± 1.16cd 3.68 ± 0.11c
4 20%PEG 2d 91.33 ± 1.53a 4.51 ± 0.15a
5 25%PEG 2d 83 ± 2.00bcd 3.71 ± 0.19c
6 5%PEG 4d 78.33 ± 1.53de 3.26 ± 0.15d
7 10%PEG 4d 87.67 ± 1.53ab 4.15 ± 0.15b
8 15%PEG 4d 81.67 ± 2.52cd 3.58 ± 0.24c
9 20%PEG 4d 84 ± 2.00bc 3.80 ± 0.19c
10 25%PEG 4d 76.33 ± 1.53ef 3.07 ± 0.15d
11 5%PEG 6d 70.67 ± 2.08gh 2.53 ± 0.20e
12 10%PEG 6d 59 ± 4.00i 1.58 ± 0.20g
13 15%PEG 6d 67.33 ± 4.04h 2.21 ± 0.37f
14 20%PEG 6d 35.67 ± 4.51l 1.01 ± 0.06h
15 25%PEG 6d 28.33 ± 3.51j 0.88 ± 0.07h
16 SWVP 72.33 ± 1.53fg 2.69 ± 0.15e
Different lowercase letters showed significantly difference at p < 0.05. PEG = polyethylene glycol, SWVP = saturated water vapor priming.
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Fig. 5. Germination rate (A) and germination index (B) change of polyethylene glycol treatments (x-axis) for Handeliodendron bodinieri seeds. The GR (p < 0.05) and GI (p < 0.05) were higher after the 10 different PEG priming treatments with treatment times of 2 days and 4 days were higher than after saturated water vapor priming (CK). View larger in new window/tab.

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Fig. 6. Effect of ultra-dry storage on plant growth of Handeliodendron bodinieri seedlings. The different letter indicate significant differences among different treatments, and the same letter indicates no significant difference (p < 0.05 Duncan’s). View larger in new window/tab.

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Fig. 7. Effect of ultra-dry storage on plant physiology of Handeliodendron bodinieri seedlings. The different letter indicate significant differences among different treatments, and the same letter indicates no significant difference (p < 0.05 Duncan’s). View larger in new window/tab.

Table 4. The common factor variance and weight of the growth physiological index of Handeliodendron bodinieri seedlings in ultra-dry storage after planting the ultra-dry storage seeds for one year.
index Common factor variance weight index Common factor variance weight
plant height 0.949 0.052 K 0.954 0.053
stem diameter 0.798 0.044 SOD 0.867 0.048
biomass 0.933 0.052 POD 0.939 0.052
Root-shoot ratio 0.894 0.049 MDA 0.99 0.055
total root length 0.94 0.052 SS 0.875 0.048
total root surface area 0.934 0.052 SP 0.96 0.053
Average root diameter 0.898 0.050 RA 0.983 0.054
leaf area 0.908 0.050 Pn 0.714 0.039
N 0.711 0.039 Gs 0.947 0.052
P 0.975 0.054 Tr 0.932 0.051
N = nitrogen, P = phosphorus, K = potassium kalium, SOD = superoxide dismutase, POD = peroxidase activity, MDA = malondialdehyde, SS = soluble sugar, SP = soluble protein, RA = root activity, Pn = net photosynthesis, Gs = stomatal conductance, Tr = trmmol.
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Fig. 8. The seedling quality index of Handeliodendron bodinieri seedlings in ultra-dry storage. Seedling quality evaluation score of H. bodinieri seedlings from ultra-dry-stored seeds at 4 °C (0.59) and ultra-dry-stored seeds at room temperature (0.58) was significantly higher than that of seedling from sand-stored seeds (0.37).