Abstract
Light plays a vital role on the growth and development of plant. On the base of white light with high color rendering to the benefit of human survival and life, we proposed to improve “color rendering” of LED lighting for accelerating the growth of lettuce. Seven spectral LED lights were adopted to irradiate the lettuces under 150 μmol·m−2·s−1 for a 16 hd−1 photoperiod. The leaf area and number profiles, plant biomass, and photosynthetic rate under the as-prepared LED light treatments were investigated. We let the absorption spectrum of fresh leaf be the emission spectrum of ideal light and then evaluate the “color rendering” of as-prepared LED lights by the Pearson product-moment correlation coefficient and CIE chromaticity coordinates. Under the irradiation of red-yellow-blue light with high correlation coefficient of 0.587, the dry weights and leaf growth rate are 2–3 times as high as the sharp red-blue light. The optimized LED light for lettuce growth can be presumed to be limited to the angle (about 75°) between the vectors passed through the ideal light in the CIE chromaticity coordinates. These findings open up a new idea to assess and find the optimized LED light for plant growth.
Highlights
Light is the primary environmental factor for plant growth and development
The 437 nm bands belong to blue light for developing the chloroplast and the 678 nm bands are attributable to red light for promoting photosynthesis[12,13,14,15]
Where x is the spectral data points of each as-prepared Light-emitting diodes (LEDs) light and y is those of the ideal light
Summary
Caused by lack of sunshine, plant growth in northern countries and during non-native seasons has been already supported by artificial illumination[1,2] Artificial light sources such as incandescent, metal-halide, fluorescent lamps are generally used for plant cultivation. Spectral modulation produced by LED lighting plays an important role for enhancing plant development, because plant morphology and physiology are strongly influenced by the light quality, which refers to the color or wavelength reaching a plant’s surface[4]. An optimal strategy of light quality regulation would allow one to select the most efficacious spectral composition, thereby enabling plant growth in the most energy-efficient way. It is well known the white LEDs with high color rendering are conductive to human eyes. We suppose the absorption spectrum of fresh leaf to be the emission spectrum of ideal light[10], and evaluate the “color rendering” of as-prepared LED lights by the Pearson product-moment correlation coefficient and CIE chromaticity coordinates
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