直接與植物生長與分化相關的三項光反應為光合作用、光形態發生與光週性。除了光量與光照時間需注意外，光質也很重要，所謂的光質係指光源所輸出的光譜。與光合作用相關者主要為波長範圍在400∼700nm內的光量子數目，而與光形態發生反應有關的紅光（R）波長範圍為600-700nm，遠紅光（FR）波長範圍為700∼800nm。另有藍光（B）波長400-500nm亦為本研究探討的範圍。

　　當太陽光穿透物體時，其光譜因為某部份被吸收而改變了。本研究量測太陽光穿透七種不同顏色之塑膠布，五種溫室覆蓋膜，六種常見之市售玻璃紙，以及藍色硫酸銅溶液時的光譜。同時計算各波段範圍之穿透率，R/FR值和B/R值。在所有的測試材料中，三層共擠壓膜與藍色玻璃紙的R/FR值分別為最高與最低；藍色玻璃紙與橙色玻璃紙的B/R值分別為最高與最低；紫色覆蓋膜與藍色玻璃紙的穿透率分別為最高與最低。隨著硫酸銅溶液濃度以及厚度的增加，R/FR值及B/R值也隨之增加。

本研究以水耕栽培的方式種植波士頓萵苣種苗，一部份的實驗在植物生長箱中進行，分別以四支旭光一般燈管、四支紅色燈管、四支藍色燈管、兩支紅色兩支藍色燈管、三支紅色一支藍色燈管、三支藍色一支紅色燈管做為人工光源，種植25天後探討萵苣種苗的「光形態發生」反應。結果顯示在三支紅色一支藍色燈管照射下的萵苣有最大生鮮重、乾重及葉面積。另一部份的實驗在自行搭建之水耕栽培架進行，以旭光一般日光燈管、植物生長燈、飛利浦Agro-Lite燈管等人工光源，以及太陽光自然光源栽培波士頓萵苣種苗，種植40天之後探討萵苣幼苗的「光形態發生」反應。結果顯示在植物生長燈照射下的萵苣有最大生鮮重、乾重，在Agro-Lite燈照射下的萵苣有最大葉面積。

【關鍵詞】光形態發生、光譜、萵苣、水耕栽培

Plants need light to maintain alive. Besides the duration and amount of light, light quality is also important to plants. The so-called light quality means spectrum from light source. There are three light response directly related with plants growth and morphogenesis, they are: photosynthesis, photo-morphogenesis and photoperiodism. The photon flux between 400 to 700nm are mainly responsible for photosynthesis; and red light(between 600 to 700nm) and far-red light(between 700 to 800nm) are mainly responsible for photomorphogenesis. Blue light(between 400 to 500nm) is also of interest of this study.

When sun light transmitted through an object, its spectrum might be altered due to the absorbtivity of the materials in a specific wavelength. 7 different color plastic films, 5 different greenhouse covering films and 6 glassy- paper were used to study how these materials altered the sun's spectrum. Transmittance, R/FR and B/R values are major concerns in the analysis of spectral data. Among all materials, 3 layer co-extruded film and blue glassy-paper have the highest and lowest R/FR value, respectively. Blue and orange glassy-paper have the highest and lowest B/F value, respectively. Purple color film and blue glassy-paper have the highest and lowest transmissivity, respectively. Also, if the concentration and the thickness of copper sulfate solution (CuSO4) increased, the R/FR and B/R values were increased accordingly.

Boston lettuce was grown hydroponically and various artificial tube lamps were used to study the effects of light quality on the growth of lettuce seedling. First part of the experiments was conducted using growth chambers and the secend part of the experiments was conducted using self-build hydroponic system. In the first experiment, different combination of blue and red lamps were used. Daylight lamps were also used to serve as the control group. The results shown that the 3red 1blue combination has the best outcome in terms of fresh weight, dry weight and leave area. In the 2nd experiment, daylight, plant growth and Agro-Lite(from Philips) lamps were used. The results of the 2nd experiment shown that the plant growth lamp has the best outcome in terms of fresh and dry weight, while lettuce under Agro-Lite has the largest leave area.

【Keywords】Photomorphogenesis, Light Spectrum, Lettuce, Hydroponics