The responses of Endemic False Cypress Seeds of Taiwan to Water Supply Regimes during Germination
| Autor: | Hsiang-Ling Lin, 林湘玲 |
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| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 89 Chamaecyparis formosana and Chamaecyparis obtusa var. formosana are important endemic species in Taiwan. The points of natural regeneration decide by successful seed germination and seedling emergence. Moisture conditions seem to play a dominant role in regulating germination according to the natural distribution of Cypress forest. Howerve, there is no studies with water supply on germination of seeds of Chamaecyparis sp. After wind selection, the seeds of Chamaecyparis sp. were treated in the following tests with different water supply regimes: (1) Seed germinated with substance of water-mosses or filter papers or germinated under flooding condition. (2) Seeds germinated at —0.0, -0.05, —0.1, -0.2, -0.3, -0.4, -0.5, —1.0,and -1.5MPa water potentials. (3) Seeds germinated at —1.5MPa water potential of different duration of 7, 14, 21, 28days. (4) When increasing water stress from —0.05 to —1.5MPa occurred in the germinating process. (5) When cyclic water stress from —0.05 to —1.5MPa a cycle, occurred in the germinating process (6) The influence of hydrated-dehydrated cycles on the germination of seeds of Chamaecyparis sp. The results are summarized as follows: (1) The seeds of C. formosensis had higher germination percentage than C. obstua var. formosana under the condition of little oxygen by flooding. (2) C. formosensis could germinate at —0.2MPa and the germination of C. obstua var. formosana only occurred at —0.1MPa. (3)From the hydrotime equation, the base water potential(Ψb) of C. formosensis and C. obstua var. formosana are —1.77MPa and —1.85MPa, respectively. And the hydrotime(θH) of C. formosensis and C. obstua var. formosana are respectively 32.07 and 72.53MPa．H.(4) The germination percentage of C. obstua var. formosana are siginificantly lower than C. formosensis of 7, 14, 21, 28days duration of water stress of —1.5MPa. (5) When water supply decreased in the germinating process, it had no significant effect on C. formosana, but significantly lower the germination of C. obstua var. formosana. (6) When water stress occured cyclic, the germination expression of C. obstua var. formosana would fall down, but it didn’t decrease the germination of C. formosensis. (7) The germination day of C. obstua var. formosana seemed to increased with times of cycles of treatments but not achieve statistically significant difference, but no changes of seeds of C. formosensis. According to the experiment results, C. formosensis seeds could germinate at wide water supply range, and have better germination expression with lower oxygen in flooding than C. obstua var. formosana. But it doesn’t interpret the effects of the water requirement of seeds on the natural distribution of Chamaecyparis formosensis and C. obtsua var. formosana. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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