MadSci Network: Botany |
The simplest answer to that question is the fact that fluorescent light is more like natural sunlight than incandescent. By more alike, I mean that the emission line spectra of fluorescent light and sunlight are nearly the same. An emission line spectrum is a pattern of colors that is as unique to a kind of light as a fingerprint is to us. It is used to tell different kinds of light apart and different elements apart. To see an emission line spectrum, you must have a special instrument called a spectroscope. When placed at the proper angle to the light source, a rainbow will appear. This is illustrated in the picture below. This rainbow will most often be missing many colors in it. A scientist can tell which kind of light it is by which lines are missing. White light is made up of all possible colors (wavelengths) of light combined. The whole spectrum is pictured below, you know it as the rainbow. Plants need two main colors (wavelengths) of light. Red and blue. Green light is not used. It is deflected towards your eye, this is why plants appear green. If you were to look through a spectroscope at incandescent light, you would notice the prominent red lines. When red light is used alone on plants, it tends to produce leggy plants. The bulbs also produces a lot of heat in comparison to the amount of light given off. Cool white and warm White fluorescent tubes, used together, produce the best light for plant growth. Cool white emits light in the blue wavelength while warm white emits light in the red range. These two when used in the correct balance, much like sunlight, will grow healthy plants. Keep asking questions! :]
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