| Summary: | 碩士 === 國立中興大學 === 森林學系 === 92 === 本實驗主要目的在於探討不同植物之異戊二烯釋出量，及植物於缺水逆境之情況下，異戊二烯之釋出情形，以作為都市林、工業區綠化、行道樹選擇樹種時之參考依據。
利用固相微萃取法吸附植物釋出之異戊二烯，再利用氣相層析質譜儀結合冷凍捕捉裝置予以分析與定量。本實驗所選之樹種有檸檬桉、楓香、樟樹、青剛櫟及栓皮櫟等五種。其中釋出量較大的樹種為檸檬桉(32.87 mg/L)及楓香 (11.33mg/L)，樟樹之釋出量太少無法定量，而青剛櫟及栓皮櫟則測不出有異戊二烯釋出。
檸檬桉苗木在正常狀況下，光度、溫度及光合作用速率皆與異戊二烯釋出量呈正相關，而氣孔導度與異戊二烯釋出量則無明顯相關性。
檸檬桉苗木處於缺水處理期間，異戊二烯釋出量有稍微增加的趨勢，至光合作用速率接近停止時異戊二烯釋出量開始下降。恢復供水後，異戊二烯釋出量恢復情形較光合作用速率快速，且其釋出量會較正常狀況下，所測得之數值，增加兩倍。
The main purposes of this experiment was to study isoprene emitted from different plants and the effect of water stress on isoprene emission. Hopefully, these results will help in guiding the selection of species for urban forest, industrial park plantation, roadside planting and others.
The solid phase microextraction (SPME) was used to extract isoprene emitted from plants. Then the gas chromatography/mass spectrometer (GC/MS) equipped with Cryo-Trap was applied to analyze those adsorbates. Species selected in this experiment were Eucalyptus citriodora, Linquidambar formosana, Cinnamomum camphora, Cyclobalanopsis glauca, and Quercus variabilis. The amount of isoprene emitted from plants were in the following order: Eucalyptus citriodora (32.87 mg/L), Linquidambar formosana (11.33 mg/L), Cinnamomum camphora (trace), Cyclobalanopsis glauca and Quercus variabilis (nondetectable).
Isoprene emission is increased with light intensity, leaf temperature and photosynthesis rate. Stomatal conductance and isoprene emission have shown no positive relationship.
During the water stress period, the isoprene emission from the seedling of Eucalyptus citriodora was slightly increased and then dropped when the photosynthesis rate was closely to zero. After rewatering, the isoprene emission was recovered faster than photosynthesis rate and the amount of isoprene emitted was twice as much as in the normal condition.
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