ABSTRACT
Plants use sunlight for photosynthesis and, as a consequence, are exposed to solar ultraviolet (UV) radiation (280–400 nm). Solar UV radiation is a part of the solar electromagnetic spectrum, which is generally divided into three classes: UV-A (315–400 nm), UV-B (280–315 nm), and UV-C (≤280 nm). The UV-C is completely absorbed by the Earth’s atmosphere, while UV-B and UV-A can reach the surface of the Earth. The level of UV-B radiation reaching the Earth’s surface is mainly influenced by the stratospheric ozone, which is the primary UV-B absorbing component. The ozone layer directly absorbs about 90% of the UV-B radiation (McKenzie et al. 2007). The level of UV-A reaching the Earth’s surface is independent of ozone concentration, since it is not attenuated by ozone, and it causes negligible damage to biological systems (Caldwell and Flint 1997; Solomon 2008).
