Abstract
1 Introduction
Nearly half of the land in Tibet is arid or semi-arid. Due to its special topographical, geomorphic and climatic conditions, the natural conditions are harsh, the ecosystem is fragile, and the carrying capacity is very limited (
2 Materials and methods
2.1 Plant materials
The study materials used in this study were
Source of | Geographical | Elevation (m) | Compact form |
---|---|---|---|
Linzhi | 93° 94′ N, 29° 79′ E | 3117 | LZS |
Linzhou | 91° 08′ N, 29° 88′ E | 3889 | LZX |
Xietongmen | 88° 21′ N, 29° 42′ E | 3891 | XTM |
Sog | 93° 79′ N, 31° 83′ E | 3940 | SX |
Longzi | 92° 32′ N, 28° 42′ E | 3948 | LZ |
Namling | 89° 08′ N, 29° 64′ E | 3949 | NML |
Purang | 81° 16′ N, 30° 34′ E | 4061 | PL |
Dingjie | 87° 77′ N, 28° 37′ E | 4163 | DJ |
Gyirong | 85° 32′ N, 28° 89′ E | 4198 | JL |
Sa’gya | 87° 90′ N, 29° 00′ E | 4233 | SJ |
Damxung | 91° 05′ N, 30° 51′ E | 4333 | DX |
Tingri | 87° 04′ N, 28° 47′ E | 4413 | DR |
Table 1.
Locations where P.centrasiaticum seedlings were collected in 12 sites in Tibet
2.2 Experiment design
Seedling cultivation: According to the germination rate test, the
2.3 Index measurement and methods
The formula for calculation of PEG-6000 for different water potentials (
where
The methods used for determination of physiological indexes: The content of malondialdehyde was determined by a kit method. The content of proline was determined by Ninhydrin colorimetry. The content of total chlorophyll, chlorophyll a, chlorophyll b and carotenoid were determined by Colorimetry (
The calculation formula for the membership function method: The parameters of proline and chlorophyll content that correlated positively with drought resistance were expressed in the following formula (
The parameters of malondialdehyde content that correlated negatively with drought resistance were expressed in the following formula:
where
2.4 Statistical analysis
Data were collected in Excel 2016, variance analysis was conducted using SPSS 19 software, the LSD method was used to carry out multiple comparisons of
3 Results
3.1 Differences of MDA among the sites
For the control, the MDA content of seedlings from Linzhi was the highest, and the MDA content of seedlings from Tingri was the lowest (
Figure 1.
3.2 Differences of Pro in seedlings from different sites
For the control, the Pro content of seedlings from Linzhi, Linzhou and Xietongmen was higher, significantly higher than that in other areas (
Figure 2.
3.3 Differences of chlorophyll in seedlings from different sites
In the control, the chlorophyll content in
Figure 3.
3.4 Comprehensive evaluation
The results of the above indexes can only indicate the total physiological response of a single index under drought stress, and it is difficult to judge the drought resistance capacity of specific regions. Using the membership function analysis method, the membership function values of the 12
Sites | MDA | Pro | Chlorophyll | Average membership | Ranking |
---|---|---|---|---|---|
Linzhi | 0.341 | 0.746 | 0.232 | 0.440 | 8 |
Linzhou | 0.460 | 0.768 | 0.515 | 0.581 | 2 |
Sog | 0.505 | 0.379 | 0.662 | 0.515 | 3 |
Xietongmen | 0.318 | 0.834 | 0.637 | 0.596 | 1 |
Longzi | 0.714 | 0.326 | 0.165 | 0.402 | 11 |
Namling | 0.737 | 0.398 | 0.207 | 0.448 | 6 |
Purang | 0.515 | 0.438 | 0.366 | 0.440 | 9 |
Dingjie | 0.647 | 0.390 | 0.263 | 0.433 | 10 |
Gyirong | 0.729 | 0.229 | 0.372 | 0.443 | 7 |
Sa’gya | 0.651 | 0.296 | 0.178 | 0.375 | 12 |
Damxung | 0.680 | 0.407 | 0.302 | 0.463 | 4 |
Tingri | 0.740 | 0.340 | 0.289 | 0.456 | 5 |
Table 2.
Membership function values of drought resistance indexes and comprehensive drought resistance ranking of P.centrasiaticum from 12 sites
4 Discussion
4.1 Relationship between membrane lipid peroxidation and drought resistance
Plant cell membranes play an important role in maintaining the stability of cells. Drought stress subjects plants to peroxidation and change in the content of MDA in the plants (
4.2 Relationship between osmoregulation substances and drought resistance
Osmoregulation is an important physiological mechanism for plants to adapt to drought stress, and as a result, has become the most active research field in drought resistance physiology (
4.3 Relationship between photosynthetic physiology and drought resistance
When a plant is under drought stress, the stomata on the leaves close, and the amount of carbon dioxide absorbed by the plant is reduced, resulting in a slowdown of photosynthesis. The decrease of chlorophyll content in plants with strong drought resistance was small, while the decrease in plants with weak drought resistance was large (
5 Conclusions
In summary, the balance between production and elimination of reactive oxygen species in
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