碩士 / 國立中興大學 / 森林學系所 / 99 / The purposes of this study were to investigate seasonal dynamics of nodule and free-living nitrogen fixation rate of Casuarina equisetifolia and Pongamia pinnata in the coastal windbreak forest at Houlong, Miaoli, to understand the habitat’s nitrogen supply conditions and plants nutrient dynamics in the soil.
2 years and 6 years old of the dominant and suppressed trees were selected in the study plots, using the acetylene reduction method to determine the activity of nodule and free-living nitrogen fixation. The nitrogen and phosphorus nutrients in the soils and plants were also investigated.
The results showed that the two species owned the largest nitrogen fixation activity in June, 2009 (8.38~15.05 ; 9.37~29.40 C2H4 hr-1 g dwt-1); and the minimum nitrogen fixation activity from October, 2009 to January, 2010 (0.22~0.71; 0.38~1.18 C2H4 hr-1 g dwt-1). On both Casuarina and Pongamia, there is significant positive correlation between plant total nitrogen concentration and nodule nitrogenase activity (p＜0.01). Moreover, in Pongamia, dominant trees have higher nodule nitrogenase activity than those of suppressed. It clearly showed that nodules nitrogen fixation could help the plant growth. This study also found that the free-living nitrogen fixation potential of the soil and the nodule nitrogenase activity in seasonal changes were negatively correlated with growth potential and plant total nitrogen concentration. It was speculated that the root exudate is the free-living nitrogen bacteria’s energy source related to the carbon / nitrogen ratio in plants.
This study demonstrated that there are seasonal changes in nodules and free-living nitrogen fixation of Casuarina and Pongamia. However, there is negative correlation between nodule nitrogenase activity and free-living nitrogen-fixing has a negative correlation. The higher the nodule nitrogenase activity is, the more it helps the growth of trees.
| Identifer | oai:union.ndltd.org:TW/099NCHU5360017 |
| Date | January 2011 |
| Creators | Chia-Ying Huang, 黃家瑩 |
| Contributors | Chiang-Her Yen, 顏江河 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 50 |
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