In addition to the light visible to humans (400 nm 700 nm) plants see or use other radiation too. The 400 nm700 nm wavelength range is called Photosynthetically Active Radiation or PAR. Much of the light that plants need is in this range, but for optimal growth result, UV light (280 - 400 nm) and/or far-red light (700-800 nm) might be important. For example far-red is critical for the flowering of many plants. All light is not equal to plants, ie. some areas are more important than others.
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1) Valoya AP67 General Growth Spectrum
For vegetative and generative growth. Performs very well with a large variety of plants, ranging from cucumber and tomato to lemon trees and even snow algae. It provides strong vegetative growth and early flowering of plants. With some leafy green plants elongation is achieved, while with some flowers the growth result is a compact plant. The AP67 spectrum has also been shown to promote quick and good rooting. The AP67 is strong on far-red (about 18 % of the total radiation) and has no UV radiation. Suggested use: Suitable for most vegetables e.g. cucumber, flowers and tree seedlings. Also positive results with algae. Appearance to humans: Pinkish light, quality control possible, good working environment.
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A good balanced ratio between red and blue light, needs to be complemented with far-red and green in right proportions for the right applications.
For example far-red, 700800 nm is critical for flowering of many plants. Less is known about the green, 500600 nm area, but recent research is finally able to conclude that this is also important for plant development. Besides being potentially harmful, plants also show photomorphogenic responses to UV-B (280-315 nm) radiation. Both UV-B and UV-A (315-400 nm) radiation are important in inducing production of phenolics, anthocyanins (coloration) and antioxidants in plants. Thus the full spectrum from about 350750 nm at a suitable light intensity is interesting in plant cultivation. The key is then to create a light which is optimally suitable for its task, by balancing the different areas so that the plant gets the right energy and signals to achieve the growers goals.*
