以模型分析綠光與黃橙光對波士頓萵苣鮮重之影響

Modelling The Effects of Green and Yellow-orange Light on Fresh Weight of Boston Lettuce

光提供植物行光合作用的能源，而綠光對植物的影響一直有爭議，包括其有益於作物成長、減少作物成長以及綠色作物不需綠光等。本研究旨在釐清綠光與黃橙光對水耕栽培的波士頓萵苣鮮重之影響。使用不同品牌的一種螢光燈管（代號T5）與七種發光二極體（light emitting diode, LED）燈管（代號分別為T-A、T-Y、T-N、T-M、E-CW、G-CW與E-WW）共計八種人工光源，對室內水耕栽培的波士頓萵苣（Lactuca sativa L.＂Ostinata＂）提供光合作用所需之光照，並以所開發模型分析各光譜波段對其鮮重增加之影響。結果顯示以藍（400-500 nm）、綠（500-600 nm）與紅（600-700 nm）三區段光譜進行分析時，各段光譜對波士頓萵苣鮮重增加的貢獻無法釐清；而以五區段光譜（400-475 nm藍光、475-525 nm藍綠光、525-575 nm綠光、575-625 nm黃橙光與625-700 nm紅光）進行分析時，則可有效判別不同波段對波士頓萵苣鮮重增加的貢獻度。其中綠光（525-575 nm）對鮮重增加的貢獻度與紅光（625-700 nm）和藍光（400-475 nm）的貢獻度相比時差異不大；但是高G_（540）/B_（450）值會減少萵苣鮮重增加。故適量比例的綠光可以促進生長，過高比例的綠光則會減少生長，而黃橙光（575-625 nm）會減少萵苣生長。 Light provide energy for plant photosynthesis. The contribution of green light to photosynthetic activity has some controversy from different literatures, including to improve or suppressing plant growth, or not needed for green plant. This study aimed to clarify the effects of various spectral sections especially on green and yellow-orange light for the production of lettuce in hydroponic system. Eight types of light sources (1 fluorescent lamp and 7 LED lamps: T-A, T-Y, T-N, T-M, E-CW, G-CW, and E-WW) were used as the sole light source to cultivate Boston lettuce (Lactuca sativa L. 'Ostinata'). The spectral range of photosynthetically active radiation (PAR, 400-700 nm) was separated into 3 or 5 sections and the contributions of each spectral section on fresh weight gained were quantified. The results indicated that the conventional method of separating range of PAR into red, green and blue at 100 nm apart was not accurate enough to clarify the contribution of different spectral sections on fresh weight of Boston lettuce. However separating into 5 sections can fulfill the analysis. The green light (525-575 nm) was equally important on the red (625-700 nm) and blue (400-475 nm) to plant growth, but high G_(540)/B_(450) reduced lettuce growth. The proper green light to PAR spectrum could promote, while high amount of green light reduced, plant growth. Yellow-orange light (575-625 nm) would reduce the growth of lettuce.