飽和脈衝葉綠素螢光影像系統之建立 及於植物光熱逆境生理之應用

Abstract

本研究開發了飽和脈衝螢光影像系統，以進行植物光熱逆境之生理狀態分析。系統中的光平面系統是藉由可程式邏輯控制器，依飽和脈衝葉綠素螢光量測方式所需要的弱調控光、光化學能光及飽和脈衝光三種不同強度光源，進行時間序列之控制。 影像擷取平台則搭配不同螢光激發狀態，進行攝影機訊號增益倍率之調控，以解決攝影機動態範圍之能力不足問題，再藉由影像擷取頻率之自動調變，增加螢光劇烈變化階段之時間解析能力，以及減少在螢光反應趨於穩定時之取樣速度；並於取像時一併記錄擷取影像之時間，再以自行開發之螢光影像處理程序，分析完整之螢光影像資訊。 當植物處於正常狀態和不同光熱逆境階段時，經由本系統分析所得之『葉綠素螢光非光化學淬熄指標』、『葉綠素螢光非光化學淬熄指標變化曲線』和『螢光指標強度影像』等三種螢光指標，相較於市售MINI-PAM之量測結果，驗證本系統具備檢測植物逆境生理變化之能力。 此外，因本系統可以獲得完整葉面之螢光反應，考慮葉面上各部位因逆境所產生之變異，與市售單點儀器比較後，本系統量測逆境植物有更為一致之量測結果。飽和脈衝葉綠素螢光影像系統提供另一種途徑，可讓研究者以非破壞性的方式探討植物生理現象。

In this article, the saturation pulse fluorescence imaging system (SPFIS) was developed to analyze to physical status of plants under light and heat stress. One part of SPFIS, the light plane system, was controlled by a programmable logic controller (PLC) to supply three different lighting conditions, including weak modulated measuring beam, continuous actinic light and saturating pulse lights, during measuring period. The other part of SPFIS, fluorescence imaging system, was developed to grab images with different signal gain setting of the CCD camera according to the different lighting conditions. The function of gain setting was used to overcome the insufficiency of camera dynamic range. Besides, the imaging frequency of SPFIS was auto adjusted to increase the time resolution when the fluorescence reaction change quickly and to decrease the sampling rate when the fluorescence reaction is stable. The imaging time was also recorded. The serial fluorescence images and the time record of plants were computed by the designed image processes to extract the complete fluorescence image information. The plants, under normal and different phases of light and heat stress, were analyzed by SPFIS to obtain three fluorescence results, including non-photochemical quenching of chlorophyll fluorescence, non-photochemical quenching curve of chlorophyll fluorescence, and intensity image of fluorescence index. Compared with the measurement results of the same plant by mini-PAM, SPFIS had the ability to detect the variation of physical status when plants were under stress. Moreover, according to SPFIS could obtain the complete fluorescence reaction of full leaves and consider the variations of full leaves under stress, the measurement results showed more consistent than mini-PAM, when plants were under stress condition. Saturation pulse fluorescence imaging system provides another way for research workers to monitoring plant physiological in non-destroy style.