Transcript UV- influence on plants.

Made by: Agata Skwara
UV radiation
Ultraviolet (UV) light is electromagnetic radiation with a wavelength
shorter than that of visible light, but longer than X-rays, in the range
10 nm to 400 nm, and energies from 3eV to 124 eV. It is so named
because the spectrum consists of electromagnetic waves with
frequencies higher than those that humans identify as the color violet.
Although ultraviolet is invisible to the human eye, most people are aware
of the effects of UV through the painful condition of sunburn, but the
UV spectrum has many other effects, both beneficial and damaging, to
human health.
UV light is found in sunlight and is emitted by electric arcs and specialized
lights such as black lights. It can cause chemical reactions, and
causes many substances to glow or fluoresce. Most ultraviolet is
classified as non-ionizing radiation. The higher energies of the
ultraviolet spectrum from about 150 nm ('vacuum' ultraviolet) are
ionizing, but this type of ultraviolet is not very penetrating and is
blocked by air.
Types of UV radiation
UVA
UVA was once thought to have a minor effect on skin
damage, but now studies are showing that UVA is
a major contributor to skin damage. UVA
penetrates deeper into the skin and works more
efficiently. The intensity of UVA radiation is more
constant than UVB without the variations during
the day and throughout the year. UVA is also not
filtered by glass.
UVA - 320 to 400 nm
UV-B
UVB affects the outer layer of skin, the
epidermis, and is the primary agent
responsible for sunburns. It is the most
intense between the hours of 10:00 am and
2:00 pm when the sunlight is brightest. It is
also more intense in the summer months
accounting for 70% of a person's yearly UVB
dose. UVB does not penetrate glass
UVB - 290 to 320 nm
UV-C
UVC radiation is almost completely
absorbed by the ozone layer and does
not affect the skin. UVC radiation can be
found in artificial sources such as
mercury arc lamps and germicidal lamps
UVC - 100 to 290 nm
Types Of UV radiation in sphere of atmosphere
Influence UV-B on plants
In the experiment conducted in the greenhouse, the
different doses of UV-B radiation applied to the two species
Avena
fatua and Setaria viridis induced changes in leaf and plant
morphology. It was a decrease of plant height, fresh mass
of
leaves, shoots and roots as well as leaf area. Besides, it
caused the leaf curling in both of the species. The
significant
differences between Avena fatua and Setaria viridis in the
studied traits were mainly due to the tillering ability of the
species. The content of chlorophyll varied considerably.
The average values of leaf greenness (SPAD units) for oats
were
about 43 while for green foxtail 32, respectively. UV-B did
not reduce leaf weight ratio, shoot dry matter, shoot to root
ratio and leaf area ratio.
UV-B, respecFigure 1. Effect of radiation on the plants of Avena fatua
(from the left 0, 4, 8 and 12 kJ/m2/d tively)
Figure 2. Effect of radiation on the plants Setaria viridis
(from the left 0, 4, 8 and 12 kJ/m2/d UV-B, respectively
Bibliography
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http://www.cazv.cz/2003/PSE3_03/8-zuk.pdf
http://www.ccpo.odu.edu/~lizsmith/SEES/ozone/cl
ass/Chap_1/index.htm
http://dermatology.about.com/cs/agingskin/g/uva.ht
m
http://www.onlinephotographers.org/pl/foto/2438/
http://rafik450.pinger.pl/m/3586904/trawa