3.1 Fiber morphology
The mean fiber length of F. strictus from three distribution areas was 1.30 mm, the mean width was 21.57 µm, the mean slenderness ratio was 60.79 µm, the mean wall thickness was 4.21 µm, the mean lumen diameter was 7.22 µm, and the runkel ratio was 1.22 µm.
3.1.1 Morphological characteristics of culm fiber in different locations
Fibers of F. strictus culms from different locations had different performance in terms of fiber characteristics (Fig. 2). The average fiber length in MJ was significantly larger than that in JP and LC. The average fiber width was decreased in the order of MJ > LC > JP, and significant differences was observed among the three locations. The mean of fiber slenderness ratio was the greatest in LC (62.54 µm) with insignificant difference among different locations. The mean wall thickness and runkel ratio was the greatest in MJ. However the lumen diameter of the culm in MJ was the smallest. The wall thickness of the MJ was significantly larger than that of JP and LC. The lumen diameter of the JP was larger than that of the MJ. The runkel ratio of the MJ was larger than that of the JP and LC. (Table 2).
In JP, the fiber length, width, slenderness ratio and wall thickness of 3-year culms was larger than that of 1- and 2-year culms. The wall thickness of 3-year culms was significantly larger than that of 1-year culms. However, insignificant difference in fiber length was observed among different portions of the culm (Fig. 3). The lumen diameter of the bottom portion of the culm was significantly greater than the middle portions.
In MJ, the greatest fiber length and slenderness ratio was found in 2-year culms. 3-year culms had greater width and lumen diameter than that of 1- and 2-year culms. The wall thickness and runkel ratio of 2-year culms was larger than that of 2- and 3-year culms. (Fig. 3) The middle portions had significantly larger the width than the top and bottom portions. No significant difference in length, slenderness ratio, wall thickness, lumen diameter and runkel ratio were observed among different portions of the culm (Fig. 2).
In LC, 3-year culms was the longest fibers. The width of 1- and 2-year culms was significantly greater than that of 3-year culms, whereas the smallest slenderness ratio was observed in 1-year culms. The fiber slenderness ratio presented a decreasing trend with increasing culm ages (Fig. 3). The bottom portion had greater fiber length and lumen diameter than the top and middle portions. No significant differences in the width, slenderness ratio, wall thickness and runkel ratio were observed among different culm portions (Fig. 2).
3.1.2 Morphological characteristics of culm fibers in different ages
The fiber wall thickness in F. strictus culm increased with the culm age and reached the maximum values in 3-year culm (Table 2). For 1-year culm, the fiber length, width, slenderness ratio, wall thickness, lumen diameter and runkel ratio was the largest in MJ, while the fiber slenderness ratio of the 2-year culms was the smallest in MJ. The fiber length, width, slenderness ratio and lumen diameter were the smallest in 1-year culms. Significant differences in wall thickness was observed among different 1- and 3-year culms, the fiber wall thickness of 3-year culms was larger than that of 1-year culms (Fig. 2).
Table 2
Fiber morphology of bamboo culm in different locations, ages and portions
|
|
Length
(mm)
|
Width
(µm)
|
Slenderness Ratio
(L/W)
|
Wall thickness
(µm)
|
Lumen diameter
(µm)
|
Runkel Ratio
(2Wt/Ld)
|
Location
|
JP
|
1.08 ± 0.05b
|
18.57 ± 0.48b
|
58.11 ± 1.73a
|
3.95 ± 0.18b
|
8.16 ± 0.50a
|
1.00 ± 0.07b
|
|
MJ
|
1.45 ± 0.05a
|
23.49 ± 0.81a
|
62.00 ± 2.46a
|
4.93 ± 0.17a
|
6.11 ± 0.15b
|
1.62 ± 0.06a
|
|
LC
|
1.36 ± 0.04a
|
21.80 ± 0.67a
|
62.54 ± 1.99a
|
3.74 ± 0.15b
|
7.38 ± 0.62ab
|
1.05 ± 0.06b
|
Age
|
1
|
1.31 ± 0.09a
|
21.50 ± 1.17a
|
60.55 ± 2.47a
|
3.96 ± 0.22a
|
7.40 ± 0.61a
|
1.14 ± 0.11a
|
|
2
|
1.23 ± 0.05a
|
20.92 ± 0.82a
|
58.98 ± 2.11a
|
4.24 ± 0.27a
|
6.54 ± 0.47a
|
1.33 ± 0.11a
|
|
3
|
1.38 ± 0.06a
|
22.31 ± 0.89a
|
61.79 ± 1.58a
|
4.42 ± 0.23a
|
7.71 ± 0.49a
|
1.20 ± 0.12a
|
Position
|
Top
|
1.27 ± 0.07a
|
21.48 ± 0.94a
|
59.02 ± 1.38a
|
3.97 ± 0.21a
|
6.86 ± 0.49a
|
1.21 ± 0.11a
|
|
Middle
|
1.31 ± 0.07a
|
22.27 ± 0.98a
|
58.81 ± 1.57a
|
4.26 ± 0.25a
|
6.87 ± 0.46a
|
1.28 ± 0.11a
|
|
Bottom
|
1.33 ± 0.08a
|
20.98 ± 1.00a
|
63.49 ± 2.72a
|
4.40 ± 0.25a
|
7.93 ± 0.61a
|
1.18 ± 0.13a
|
Mean
|
1.30 ± 0.01
|
21.57 ± 0.18
|
60.79 ± 0.59
|
4.21 ± 0.14
|
7.22 ± 0.31
|
1.22 ± 0.07
|
Note: Means followed by the same letter in the same column are not significantly different at 0.05 probabilities
|
For the 1-year culms, the value of fiber morphology were the largest in the MJ. The value of fiber morphology were the smallest in the JP (Fig. 3). The fiber length and width of MJ and LC was larger than that of JP. The fiber runkel ratio of MJ and JP was larger than that of LC. No significant differences in the slenderness ratio, wall thickness and lumen diameter were observed among different locations.
For the 2-year culms, the fiber length of the MJ and LC had significantly larger than that of the JP. The fiber width, wall thickness and runkel ratio of the MJ were significantly larger than that of the JP and LC. The slenderness ratio of the LC was largest and the lumen diameter of the JP was largest (Fig. 3).
In the 3-year culms, the fiber length of JP had significantly smaller fiber length than the MJ and LC. The fiber width of culm had significant difference in locations and the fiber width of the MJ was largest. The LC had significantly smaller fiber wall thickness than the MJ. The JP and LC had significantly smaller runkel ratio than the MJ. No significant differences in the slenderness ratio and lumen diameter were observed among different locations.
3.1.3 Morphological characteristics of culm fiber in different portions
The fiber length, slenderness ratio, wall thickness and lumen diameter average in bottom portions of F. strictus culm showed the greatest, the fiber width and runkel ratio average in middle portions of F. strictus culm showed the greatest (Table 2). The slenderness ratio was increased in the order of bottom portions > middle portions > top portions. The lumen diameter in bottom portions of JP had significantly larger than that in middle portions of JP. The width in middle portions of MJ had significantly larger than that in bottom portions of MJ (Fig. 2). No significant difference in fiber length, slenderness ratio, wall thickness and runkel ratio were observed among different portions of the culm.
For the top portion of the culms, the fiber length, width and runkel ratio of MJ had significantly larger than that of JP. The lumen diameter of JP had significantly larger than that of MJ. No significant difference in the slenderness ratio and wall thickness were observed among different portions of the culm.
For the middle portion of the culms, the fiber length of MJ had significantly larger than that of JP, the fiber width was significant difference in the order of MJ > LC > JP, the wall thickness of MJ had significantly larger than that of JP and LC, the runkel ratio was significant difference in the order of MJ > JP > LC. No significant difference in the slenderness ratio and lumen diameter were observed among different locations.
For the bottom portion of the culms, the fiber length of MJ and LC had significantly larger than that of JP, the fiber width of MJ had significantly larger than that of JP and LC, the lumen diameter of JP had significantly larger than that of MJ, the runkel ratio of MJ had significantly larger than that of JP and LC. No significant difference in the slenderness ratio and wall thickness were observed among different locations.
3.1.4 Frequency distribution of the mean fiber length
According to the classification standards of the International Council of Wood Anatomy, the length of short fiber is below 0.9 mm, medium fiber is in the range of 0.9 mm and 1.6mm, and long fiber is above 1.6 mm (Li et al. 2017). The proportion of long and medium fibers were larger in F. strictus culm, the proportion mean of long fiber was 23%, the medium fiber was 59.5% and the short fiber was 17.5%. The frequency distribution of fiber length of F. strictus culm varied greatly between locations, ages and portions. The proportion of long fiber was the highest in MJ (36.6%), followed by LC (23.0%) and JP (10.0%), while JP had the highest proportion of short fiber. The medium fibers demonstrated an increasing trend with culm ages, and the proportion of long fibers reaches its maximum in 3-year culms. The proportion of long and medium fibers in the middle portion of the culm was greater than that in the top and bottom portions (Table 3).
Table 3
Frequency distribution of fiber length of Ferrocalamus strictus culm in locations, ages and positions
Fiber Length (mm)
|
Location (%)
|
Age (%)
|
Portion (%)
|
Mean (%)
|
JP
|
MJ
|
LC
|
1
|
2
|
3
|
Top
|
Middle
|
Bottom
|
L ≤ 0.9
|
34.6
|
6.4
|
10.7
|
20.0
|
20.4
|
11.2
|
20.4
|
14.6
|
19.6
|
17.5
|
0.9 ≤ L ≤ 1.6
|
55.4
|
57
|
66.3
|
55.9
|
62.1
|
60.7
|
59.3
|
61.3
|
57.4
|
59.5
|
1.6 ≤ L
|
10
|
36.6
|
23
|
24.1
|
17.5
|
28.1
|
20.3
|
24.1
|
23.0
|
23.0
|
3.2 Soil elemental in different locations
The content of organic matter, total boron, available potassium and alkali-hydrolyzed nitrogen in the soil from MJ was largest than those in JP and LC. The organic matter content in the soil from MJ (109.57 g·kg− 1) was significantly higher than that from JP (59.51 g·kg− 1), the total boron content in the soil of MJ (26.50 mg·kg− 1) and LC (23.6 mg·kg− 1) were significantly higher than that in JP (6.10 mg·kg− 1), and the alkali-hydrolyzed nitrogen content in MJ (271.00 mg·kg− 1) and LC (260.00 mg·kg− 1) was significantly greater than that in JP (200.67 mg·kg− 1) (Table 4).
The contents of total phosphorus, total sulfur, total calcium, total copper, total aluminum available potassium and available phosphorus in the soil from LC was largest (Table 4). The total phosphorus content in the soil from JP (0.53 g·kg− 1) and MJ (0.56 g·kg− 1) was significantly smaller than that in LC (1.52 g·kg− 1). The soil from LC had higher total sulfur content (0.57 g·kg− 1) than JP (0.40 g·kg− 1). The content of total calcium, total copper, available potassium and available phosphorus was the greatest in the soil from LC but lowest in JP. The total potassium content showed the regularity in the soil, followed by JP (35.64 g·kg− 1), LC (22.37 g·kg− 1), MJ (7.96 g·kg− 1). The total magnesium, total iron, total zinc content showed the regularity in the soil, followed by LC, JP, MJ. (Table 4).
Table 4
Differences in soil elements in locations
Element
|
Location
|
Mean
|
JP
|
MJ
|
LC
|
O. M(g·kg− 1)
|
59.51 ± 2.25B
|
109.57 ± 15.54A
|
70.96 ± 3.53AB
|
84.30 ± 10.35
|
T.K(g·kg− 1)
|
35.64 ± 0.89A
|
7.96 ± 0.59C
|
22.37 ± 0.13B
|
20.39 ± 4.30
|
T.P(g·kg− 1)
|
0.53 ± 0.02B
|
0.56 ± 0.01B
|
1.52 ± 0.17A
|
0.77 ± 0.15
|
T.Mg(g·kg− 1)
|
3.30 ± 0.11B
|
1.16 ± 0.08C
|
5.57 ± 0.33A
|
2.85 ± 0.61
|
T.S(g·kg− 1)
|
0.40 ± 0.01B
|
0.49 ± 0.02AB
|
0.57 ± 0.06A
|
0.47 ± 0.03
|
T.Fe(g·kg− 1)
|
27.08 ± 0.86B
|
23.00 ± 0.88C
|
42.84 ± 0.37A
|
28.77 ± 2.77
|
T.Mn(mg·kg− 1)
|
185.67 ± 4.98B
|
159.75 ± 5.04B
|
1022.00 ± 78.00A
|
360.00 ± 125.87
|
T.Zn(mg·kg− 1)
|
83.33 ± 1.76B
|
37.00 ± 11.03C
|
120.00 ± 1.00A
|
70.89 ± 12.56
|
T.Al(g·kg− 1)
|
95.10 ± 1.67A
|
41.18 ± 2.69C
|
80.96 ± 0.75B
|
67.99 ± 8.76
|
T.Ca(g·kg− 1)
|
0.34 ± 0.03B
|
0.38 ± 0.04B
|
6.71 ± 2.49A
|
1.77 ± 1.02
|
T.Cu(mg·kg− 1)
|
7.10 ± 0.85B
|
8.68 ± 1.37B
|
45.80 ± 1.30A
|
16.40 ± 5.60
|
T.B(mg·kg− 1)
|
6.10 ± 0.90B
|
26.53 ± 1.66A
|
23.60 ± 3.10A
|
19.07 ± 3.39
|
Hy.N(mg·kg− 1)
|
200.67 ± 9.68B
|
271.00 ± 16.91A
|
260.00 ± 2.00A
|
245.11 ± 13.46
|
A.K(mg·kg− 1)
|
112.00 ± 15.53B
|
143.75 ± 13.12AB
|
195.50 ± 11.50A
|
144.67 ± 12.99
|
A.P(mg·kg− 1)
|
2.26 ± 0.40C
|
6.87 ± 0.94B
|
12.70 ± 2.23A
|
6.63 ± 1.46
|
A.Si(mg·kg− 1)
|
65.00 ± 3.06B
|
24.50 ± 2.99B
|
156.50 ± 52.50A
|
67.33 ± 20.05
|
Note: O.M = Organic matter; T.K = Total potassium; T.P = Total phosphorus; T.Mg = Total magnesium; T.S = Total sulfur; T.Fe = Total iron; T.Mn = Total aluminum; T.Zn = Total zinc; T.Al = Total aluminum; T.Ca = Total calcium; T.Cu = Total copper; T.B = Total boron; Hy.N = Alkali-hydrolyzed nitrogen; A.K = Available potassium; A.P = Available phosphorus; A.Si = Available silicon.
|