Environmental Engineering Reference
In-Depth Information
solution lowered its water potential, thus it became more difficult for plants to absorb enough
water. To determine the different influences of salts on water balance of two types of
soybean, the ψ
w
and RWC of ZH13 and BB52 were assayed after salt treatment. The young
seedlings and the mature seedlings were detected respectively. From the Figure 1A, B, we can
clearly see that with the increasing salt concentration the ψ
w
and RMC were reduced
increasingly severe, especially for mature seedlings of ZH13 (Figure 1A). The ψ
w
of the
leaves of mature ZH13 was reduced 11.2 times under 300 mM treatment, and the RWC of the
mature ZH13 was lessened by 64.2%. Under 200 mM NaCl treatment, there were 66.7% of
the ZH13 at mature stage displayed wither and fall which were the classical symptom of
hydropenia, while all the plants
showed
the classical symptom of hydropenia under 300 mM
NaCl treatment and more than 30% have already been dead. For the RWC, there was no
obvious difference between them in young seedlings, while in mature seedlings the BB52 had
higher RWC, especially under 300 mM NaCl treatment (Figure 1B). Compared to ZH13,
though the ψ
w
and RMC of the wild soybean BB52 were also down regulated, the degree of
the declining was quite small. Most of them were able to maintain development under 300
mM NaCl treatment. In addition, although the ψ
w
and RMC of the young seedlings were all
affected seriously, both types can manage to survive and few of them became withered.
3.2. The Effects of Salt Treatment on Proline and Glycine Betain Content
Proling is one of the most important compatible solutes. On the one hand, its
accumulation in the cells of plants is able to lower the water potential of the cell to maintain
the hydrologic balance under abiotic stress, and on the other hand, the proling acts as
molecular chaperone to stabilize the protein conformation by binding to the proteins (Maggio
et al., 2002).
Thus to some degree the content of the proline reflects the resistant ability of the plants.
Figure 2A shows that the contents of the proling were almost identical in two types soybean
under normal conditions, while
with the rise of
the salt concentration, the content of proline
was also increased obviously. For young seedlings the content of the proline began to
augment rapidly when the concentration of NaCl was above 100 mM, and the wild soybean
BB52 showed more outstanding. Under 300 mM NaCl treatment the rate of increase of
proline contents in young seedlings of ZH13 and BB52 were able to reach 34.2 and 38.2
respectively, yet the extent of the augment for mature seedlings were more sharp attaining
24.9 and 151.1 times respectively (Figure 2A).
Glycine betain is another important compatible solute with almost the same functions of
proline, therefore we also measured its changes during the salt stress. Its content showed the
same trend as proline. For the young seedlings of ZH13 and BB52, the contents of the glycine
betain were increased by 59.4% and 62.9% under 300 mM NaCl treatment, respectively
(Figure 2 B). The changes were more obvious in mature seedlings of ZH13 and BB52 and
they were 25.1% and117.2% (Figure 2 B). The pronounced difference also told us that the
wild soybean possessed better abilities of osmotic adjustment.
