2005-09-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/702905摘要：文心蘭為台灣栽種面積最大的蘭花作物，達 197 公頃，產值約4億台幣。除了切花大量外銷日本外，盆花產業也逐漸抬頭。由於文心蘭類對環境適應力較強，大部分業者便以簡易&#28201;網室栽培。但在此簡易設施環境下，夏季午後也許因為強光高溫，常使文心蘭光合作用受滯，有嚴重午休現象 (midday depression)，其詳細原因不明。因此導致植株生長不佳、品質下降。光合作用速率在中午降低的午休現象雖然也見於其他植物如茶樹，但文心蘭類在程度上似乎更為嚴重。 本計畫之主要目的在於瞭解文心蘭基本光合作用特性，並探究造成午休現象之可能原因。本年度擬比較在不同環境下，文心蘭光合作用午休現象的嚴重程度，以及在遭遇高溫逆境後，文心蘭光合作用的恢復能力。在方法上，係利用LI-6400可攜式光合作用測定儀測量淨光合作用速率、氣孔導度等，用葉綠素螢光儀測定PSⅡ光反應效率，另利用樹脂印膜法觀察氣孔開度等，以探討夏日午間導致文心蘭光合作用能力下降之原因，並進一步瞭解各項生理反應間之相關性。 台灣文心蘭栽種面積雖居蘭科作物之首，但產值遠不及蝴蝶蘭，且各項生理及栽培資訊十分缺乏，亟待加強基本生理研究，以<br> Abstract: Oncidium is the most widely grown orchid in Taiwan. The production area in 2004 was 197 hectares, with a value up to 4 billion NT dollars. Simple protected facilities, such as net houses, are adapted to grow Oncidium, since they are cost effective. However, under such environment, Oncidium suffer from reduced leaf photosynthesis at midday in the summer, leading to poor product quality. The reduced photosynthesis is also seen in some other crops such as tea, and is termed as “midday depression.” However, the degree of photosynthesis reduction in Oncidium seems to be greater than that in other crops. The causes of midday depression in Oncidium are unclear. We hypothesize they are associated with high temperature, high light intensity, and/or their interaction. The objectives of this study are to characterize the photosynthetic pattern of Oncidium, and the potential causes of midday depression, with a goal to relieve Oncidium from midday depression, leading to an improved yield and quality. Experiments will be conducted to compare net photosynthetic rates of Oncidium under different environment and to determine if the daily photosynthetic pattern would change with and without stresses. The course studies will be performed every hour from 0600 h to 1800 h on CO2 fixation, stomatal conductance, photochemical efficiency of Photosystem II (Fv/Fm), and stomatal aperture. The ability to recover from midday depression after environmental stresses will be evaluated. The association of these physiological changes will also be investigated to elucidate their relation to midday depression in Oncidium. Although Oncidium is the number one orchid in Taiwan in the order of production area, research in this major crop is very limited. Its production value is far less than that of Phalaenopsis, the lack of basic information regarding their photosynthesis and cultivation is a responsible reason. This study is expected to have a more clear understanding about the midday depression of Oncidium. This project can have positive impact at a variety of levels within the industry, including grower (better yield and quality), the consumer (more value) and the supplier (potentially increased sales). The likelihood for scientific success is relatively high, and a successful solution would provide concrete information about a continuing problem in the industry.文心蘭光合作用午休現象蘭花Oncidiumphotosynthesismidday depressionorchid