| Summary: | 碩士 === 國立臺灣大學 === 森林環境暨資源學研究所 === 95 === Abstract
This study investigated growth and physiological performance of Taiwan red cypress (Chamaecyparis formosensis) and Taiwan yellow cypress (Chamaecyparis obtusa var. formosana) in response to different light and nutrient treatments in Chi-Tou forest nursery. The seedlings were treated with 4 levels of nitrogen, 60, 120, 180, and 240 kg/ha and grown in 3 levels of light intensities, 100%, 50%, and 10% of full sunlight. The experiment was conducted from September 2004 to June 2006.
Height growth of seedlings of Taiwan red cypress was significantly greater than those of Taiwan yellow cypress in all combinations of light and nutrient treatments, especially in 50%N240. The diameter growth of both species differed significantly among light treatments. The increasment of diameter growth was increased with light intensity, with the largest diameter occurring in 100%N240. The biomass of both species also increased with light intensity. Nutrient levels significantly affected the biomass of Taiwan red cypress but not that of Taiwan yellow cypress. Foliar chlorophyll and N concentrations of both species were significantly higher in 10% of natural light than in higher light intensities. Nutrient levels significantly affected foliar of Taiwan red cypress but not that of Taiwan yellow cypress. The quantum yield of both species increased significantly with light intensity. The higher quantum yield could be related to the acclimated increased of stomatal conductance in higher light intensity. Dark respiration increased with light intensity. Higher light intensity significantly increased light compensation point of Taiwan red cypress but not that of Taiwan yellow cypress. The maximal assimilation rate of both species was lowest in 10% of natural light. Fv/Fm in both species decreased with increasing light intensity. qP and NPQ in both species increased with light intensity. The results suggested that both species grown under 100% of natural light had better adaptation to high light environment. Overall, the effect of the variation of light intensity on growth and physiological performance was significant than that of nutrient levels. None of the above chlorophyll fluorescence parameters, Fv/Fm, qP and NPQ, was affected by nutrient treatments. Compared to nutrient treatments, light treatments had significant effect on growth and physiology of seedlings. The growth performance and biomass accumulation were better in Taiwan red cypress than those of Taiwan yellow cypress.
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