Physiology and Molecular Biology of Stress ... - KHAM PHA MOI

52
Z Dajic
5. SALT ACCUMULATION
High accumulation of salts in the shoot has been well established for salt- tolerant
species (e.g. Waisel, 1972; Flowers et al., 1977; Ungar, 1991). In halophytes of the plant
community Puccinellietum limosae in Serbia, which is spread on highly salinized soil
(annual values of EC e
ranged between 20.8 dS m -1 and 54.2 dS m -1 ), the level of total salt
accumulation in the shoot during the vegetative season (June-October), and the relations
among accumulated ions (Table 2) were strictly species specific, depending on
different adaptive strategies (Dajic, 1996), such as salt accumulation in the halophytes
Suaeda maritima and Salsola soda, and salt exclusion in the halophytic grass Puccinellia
limosa.
Table 2. Average seasonal ion concentrations of the shoot (ìmol g -1 dry weight) in halophytes
grown in natural habitat conditions
Species Na + K + Mg 2+ Cl -
1 660.9 ± 317.88 438.5.1± 162.96 155.2 ± 30.32 478.9 ± 180.71
2 843.5 ± 375.38 467.3 ± 182.67 168.7 ± 32.20 615.5 ± 263.23
2 2686.9 ± 982.06 341.5 ± 86.87 391.7 ± 132.81 1877.7 ± 614.2
4 791.3 ± 234.78 365.6 ± 95.41 158.3 ± 49.31 555.5 ± 244.18
5 1345.7 ± 608.58 363.5 ± 142.98 87.5 ± 22.05 504.9 ± 188.21
6 1834.8 ± 664.11 375.2 ± 99.21 125.2 ± 56.3 901.4 ± 538.31
7 127.5 ± 64.06 157.3 ± 54.82 61.1 ± 17.33 177.5 ± 65.2
1- Atriplex tatarica, 2- Atriplex litoralis, 3- Suaeda maritima, 4- Aster tripolium var. pannonicus,
5- Camphorosma annua, 6- Salsola soda, 7- Puccinellia limosa
(after Dajic, 1996)
5.1. Vacuolar Compartmentation
The high content of salts in aboveground parts of the halophytic plants is feature
associated with efficiency of such plants to deliver ions into the vacuoles. The ability
of plants to transfer ions into the vacuole is dependent on the proportion of highly
vacuolated cells and tissues, as well as the activity of transport systems located at the
tonoplast, which prevent excessive concentration of ions in the cytoplasm. Sequestration
of salts into the leaf and/or shoot vacuoles is typical attribute of dicotyledonous
halophytes, coupled with other physiological adaptations, such as regulation of transpiration
(and water regime in general) and performing of cell metabolism with low
potassium concentrations (Flowers and Dalmond, 1992).