In recent research at Michigan State University, we delivered moderate intensities of blue light in our greenhouses in an attempt to regulate flowering and suppress extension growth. However, at a higher intensity (such as 20 μmol∙m–2∙s–1 or higher), blue light can promote flowering of long-day plants and inhibit flowering of short-day plants. Blue Light and FloweringĪt a low intensity, such as that typically used to deliver photoperiodic lighting (1-2 μmol∙m–2∙s–1), blue light does not regulate flowering of most daylength-sensitive crops. This physiological disorder typically decreases as blue/UV radiation increases. Similarly, in the absence ofīlue/UV, some plants in the tomato (nightshade) family develop intumescences, or small blisters, on leaves, stems and petioles. Thus for these crops, delivery of blue/UV radiation prior to marketing can increase crop quality attributes such as leaf coloration and nutrition. In some leafy greens crops such as lettuce, blue/UV also increases the production of healthful compounds such as antioxidants and some vitamins. For example, in the absence of blue/UV radiation, plants that have purplish leaves outdoors may have green leaves. Radiation with shorter wavelengths (blue/UV) stimulates the production of compounds that can influence leaf coloration. Research from Heidi Lindberg and Erik Runkle, MSU. Plants were grown at the same photosynthetic photon flux density (PPFD) in an environmental growth chamber. Seedlings grown indoors with blue light are often shorter, and have smaller leaves, than those grown under only red light.

There are some reports in which extension growth is actually promoted under only blue light, although this response seems to be crop specific. The utility of blue light as a growth regulator is pronounced with indoor lighting and generally has less or no growth-inhibiting effects in supplemental greenhouse lighting. In the production of ornamentals, these attributes can be desirable because in essence, blue light can act as a growth regulator. Generally, blue light suppresses extension growth plants grown with blue light are usually shorter and have smaller, thicker and darker green leaves compared to plants grown without blue light (Figure 1).

Therefore, indoor lighting (such as in vertical farming) and greenhouse lighting usually include blue in the spectrum. Generally, only a low intensity of blue is needed in a light spectrum for fully functional photosynthesis. In addition, blue light regulates the opening of stomata, which are the tiny openings on leaves that control both water loss and the uptake of carbon dioxide. However, at least a minimal intensity of blue light is needed in sole-source (indoor) lighting applications for normal plant growth. Blue Light and Plant Growthīlue photons drive the photosynthetic reaction, although from an energy standpoint, one might consider them less efficient than green or red photons because their high energy isn’t fully utilized some of the energy is essentially lost compared to photosynthetic photons with a longer (less energetic) wavelength. Thus, while blue light can appear somewhat dim to us, it has high energy and is useful for plant growth applications. In contrast, blue light is considered equally effective as green or red light at driving photosynthesis. Our perception of blue light, especially at shorter wavelengths (for example, 400 to 425 nm) is low compared to green This waveband is within the visible spectrum, has relatively high energy, and has pronounced effects on plant growth and flowering. Blue light is usually referred to as radiation with wavelengths between 400 and 500 nm.

7 days to die farming artificial light