Red Light Vs.
Blue Light: Which Light Color Is Better For Plant Growth?
The question of which light color is better for plants comes up from time to time. Some people believe that red light is better than blue light while others say that it depends on the type of plant and other factors such as soil quality and temperature. There are many opinions on this topic, but there isn’t any scientific evidence to support these claims either.
There are two types of light that plants need: short wavelength (red) and long wavelength (blue). Plants have receptors in their leaves called chlorophyll. Chlorophyll absorbs certain wavelengths of light, including those in the visible spectrum. These wavelengths include the colors red, orange and yellow.
When plants absorb these wavelengths they convert them into chemical energy so that they can use it to make sugars and oxygen for respiration. If plants were able to absorb all wavelengths of light, they would burn out quickly. Instead, plants convert some of the absorbed light into heat and release it through photosynthesis.
Plants are very sensitive to changes in light levels. They will die if the amount of sunlight decreases too much or increases too little. Plants cannot survive without sunlight and must get enough of it every day to stay alive.
Light is measured in units called lumens. The lumen measures how much light falls in a particular area. It is a measure of “brightness,” but it doesn’t tell us anything about the quality of light. A lumen is not the same as a lux, which is a measurement of illumination or the “intensiveness” of light in a particular area.
If you want to compare the brightness of two light sources, you need to measure their brightness in the same units.
The light spectrum, or the different wavelengths present in different types of light, is divided into seven main color categories: red, orange, yellow, green, blue, indigo and violet. The visible light spectrum ranges from 380 nanometers (violet) to about 750 nanometers (red). Violet is on the short wavelength side of the visible light spectrum and red is on the long wavelength side.
Visible light is only a very small part of the entire electromagnetic spectrum. This includes all the different wavelengths of light, or types of electromagnetic radiation, that are present in our environment. Our eyes can only see a very small part of the entire light spectrum. This part of the spectrum is called visible light and it’s the only type of light our eyes can detect.
Higher plants have evolved a number of specialized cells called chloroplasts to conduct photosynthesis. These chloroplasts give leaves and green plants their characteristic green color. The chloroplasts contain chlorophyll, the green pigment that absorbs light energy for plants to use in photosynthesis.
The other colors in the visible light spectrum don’t really help plants carry out photosynthesis. In fact, some of these wavelengths of light are actually harmful to plant life if they’re exposed to them for extended periods of time.
Sources & references used in this article:
Growth of potato plantlets in vitro is different when provided concurrent versus alternating blue and red light photoperiods by RC Jao, W Fang – HortScience, 2004 – journals.ashs.org
Plastic mulch color effects on reflected light and tomato plant growth by DR Decoteau, MJ Kasperbauer, DD Daniels, PG Hunt – 1988 – pubag.nal.usda.gov
Spectral distribution of light in a tobacco canopy and effects of end-of-day light quality on growth and development by MJ Kasperbauer – Plant physiology, 1971 – Am Soc Plant Biol
Plant productivity in response to LED lighting by GD Massa, HH Kim, RM Wheeler, CA Mitchell – HortScience, 2008 – journals.ashs.org
Effect of red light and blue light on the anthocyanin accumulation and expression of anthocyanin biosynthesis genes in red-leaf lettuce. by K Shoji, E Goto, S Hashida, F Goto… – Journal of Science and …, 2010 – cabdirect.org