Molecular Soil Biology 2015, Vol.6, No.2, 1-6
4
1.2 Influence of NaHCO
3
upon
S. sungkianica
seeds
germination and seeding growth
1.2.1 Influence of NaHCO
3
upon seed germination
All
S. sungkianica
seeds germinated on the second day
regardless the difference of NaHCO
3
concentration,
which means the initial germination has no relation
with it.For most plant species, seed germination rate is
highest when it happens in pure water; and drops
with the increase of NaHCO
3
. In a low NaHCO
3
environment, however, some alkali-resistant seeds
show a higher germination rate than they are in pure
water (Zeng et al., 2014; A.El-Keblawy et al., 2005).
Table 2 shows the
S. sungkianica
germination rate
first rises then falls with the increase of NaHCO
3
,
when NaHCO
3
=10 mmol/L, the number is 80.50±3.14%,
which is higher than the control group (0 mmol/L,
77.00±2.12%), and shows no signs of significant
differences (P>0.05). Other indexes like seeding length,
germination potential, GI and VI all reach their
highest points when NaHCO
3
=10 mmol/L, while the
numbers are much lower in the control group (P<0.01).
When NaHCO
3
=30 mmol/L, the germination rate,
thus 62.50 ± 1.99%, much lower than the control
group; nonetheless, the rate was still as high as
18.00±0.83% when NaHCO
3
=50 mmol/L. The linear
regression equation is
y
=
-
1.298
x
+113.159,
R
2
=0.954,
The alkali-tolerance limit, semi-lethal alkali
concentration, and alkali concentration of
S.
sungkianica
seeds are 67.92, 48.66, and 29.39 mmol/L,
respectively. In the re-germination experiment, which
all the un-germinated seeds were put into pure water,
result shows that seeds under stress treatment mostly
turn dark-brown and lose its germination ability; those
color remain unchanged, however, can re-germinate.
And the rate of dark-brown seed rose with the increase
of NaHCO
3
concentration.
Table 2 Effect of NaHCO
3
on the growth of the seedlings of
S. sungkianica
Item
Concentration of NaHCO
3
(mmol/L)
0
10
20
30
40
50
Germination percentage
(%)
77.00±2.12ab
80.50±3.14a 70.00±2.23b
62.50±1.99c
54.00±1.58d
18.00±0.83e
Seeding length (mm)
5.03±0.34b
7.92±0.42a
7.76±0.39ab
5.01±0.19c
2.75±0.12d
2.64±0.11e
Germination potential
(%)
74.50±2.08a
77.50±2.96a 67.00±2.19b
61.00±1.78c
52.00±1.45d
10.50±0.77e
Germination index
56.50±4.02a
58.88±3.89a 51.00±3.44b
46.13±3.65c
39.50±1.24d
19.50±1.22e
Vigor index
79.66±5.99b
128.94±5.32a 85.17±4.45b
52.12±3.11c
29.63±1.59d
5.52±2.03e
1.2.2 Influence of NaHCO
3
upon anatomical
structure of seeding roots
Figure 3-A is the anatomical structure of
S. sungkianica
root. From out to core, the cross section is divided by
epidermis, cortex and vascular bundle, with the
presence of aerenchyma. The
S. sungkianica
showed a
strong resistance when NaHCO
3
= 10 mmol/L (Figure
3B), the anatomical structure is still intact, with no
significant differences with that of the control group.
When NaHCO
3
=30 mmol/L (Figure 3C), the epidermis
and exodermis all disappear while the parenchymatous
become the protective tissue, and the aerenchyma is
also disappear; the radial and tangential walls of the
cortical cell show a tendency of thicken, as for
vascular bundle, the number of vessels in primary
xylem decrease but enlarged in diameter, which is
good for the water transportation and the physiological
metabolism of plants (Wang, 2012).
1.2.3 Influence of NaHCO
3
upon the anatomical
structure of seeding lamina
Figure 4-A shows the anatomical structure of
S.
sungkianica
lamina of the control group, of which
includes upper epidermis, mesophyll tissue and lower
epidermis, with no epidermal hair but covered with
cuticle. When NaHCO
3
=10 mmol/L (Figure 4B),
compare to control group, the lamina structure
remains intact, lamina and both upper and lower
epidermis cells are thickened, which means the lamina
grew better in this condition (Werner et al., 1990);
when NaHCO
3
= 30 mmol/L (Figure 4C), both upper
and lower epidermis cells become shrunk and the
