# Plants and uv?



## PoohBear (May 19, 2007)

Do plants utilitze any UVA or UVB?


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## hoppycalif (Apr 7, 2005)

From: http://www.nas.nasa.gov/About/Education/Ozone/radiation.html
Both plants and phytoplankton vary widely in their sensitivity to UV-B. When over 200 agricultural plants were tested, more than half showed sensitivity to UV-B light. Other plants showed neglible effects or even a small increase in vigor. Even within a species there were marked differences; for example one variety of soybean showed a 16% decrease in growth while another variety of the same soybean showed no effect [R.Parson]. An increase in UV-B could cause a shift in population rather than a large die-off of plants

From: http://www.littlegreenhouse.com/guide3.shtml
UVB is harmful, causing plant colors to fade
UVA is neither harmful nor beneficial


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## rs79 (Dec 7, 2004)

At high altitiudes plants, that is, trees, are dwarfed because of UV. This is how Bonsai got started.


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## elaphe (Aug 24, 2006)

Algae likes UVA and UVB! On my turtle tubs, I have ZooMed UVB bulbs over the basking end and GE daylight bulbs on the other end. Algae only seems to really take off on the end with the UVB bulbs. There is also some light that gets in from the GE Reveal bulbs that I use for heat lamps. 

One other thing I've noticed is that the hornwart that gets pushed to this end from the current tends to grow in yellow/red instead of green like it does under the daylight bulbs (if it doesn't get eaten first!).

I don't know if this helps, but it's what I've seen in my experience.

Brian


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## jazzlvr123 (Apr 29, 2007)

All UV does is Kill algae and bacteria in the water ass it flows through. It does not affect the growth of the plants because the plants do not receive UV light. only the water that passes through the cannister gets UV light.


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## hoppycalif (Apr 7, 2005)

I think the question related to tank lighting instead of UV sterilizers. But, the comment raises a question: How can algae grow well in UVB, but a UV sterilizer kills algae??


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## elaphe (Aug 24, 2006)

hoppycalif said:


> I think the question related to tank lighting instead of UV sterilizers. But, the comment raises a question: How can algae grow well in UVB, but a UV sterilizer kills algae??


A UV sterilizer utilizes a different wavelength of UV. It's called UVC. In most diurnal reptiles (not sure about plants) UVA is what causes a general good feeling, good appetite, better breeding success, etc. UVB is used to make vitamin D3 for the assimilation of calcium. UVC is just all around bad for any life form.

Pretty much any fluorescent bulb is going to put out some UVA. Incandescent lamps also put out UVA. UVB is much more expensive to make. Only special fluorescent lamps, mercury vapor, metal halide, etc make UVB. I noticed on the spectral chart for my Giesemann Midday bulbs that they produce a very small amount of energy in the UVA range, but none in the UVB. I don't run any kind of glass shield between these and the tank and my plants seem to do fine. I bet if I were to put a UVB producing bulb over the tank, the results would change drastically. UVA can give you a sunburn, but UVB is what gives you a "really good" sunburn! I'm thinking that's why my hornwart in the turtle tubs grows in yellow/red on that end of the tub?

Brian


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