Light is made up of particles of energy, known as photons. The light we see is made up of photons of different wavelengths and, thus, different colors. Ultraviolet light is invisible. Plants can use most of the colored spectrum, but not ultraviolet light.
Ultraviolet (UV) light has among the shortest wavelengths in the light spectrum. Although the sun radiates ultraviolet light, most of it is screened by the stratospheric ozone layer so it does not affect plant growth.
Microscopic Life Forms
Ultraviolet light is used to kill bacteria and other microscopic life forms. Its deadly effect is not limited to microscopic organisms, though. UV light can alter the composition of materials and conditions needed for photosynthesis, the process plants used to grow.
Scientists have been testing the effects of ultraviolet-B radiation on crops for decades due to concerns about the depletion of the ozone layer. Although the effects vary among plant species and cultivars, most plants are negatively affected to some degree.
Scientists are addressing concerns about potential crop losses by trying to develop plants that are resistant to damage from ultraviolet light.
Limiting the Effects
According to plant scientists Alan Teramura and Joe Sullivan of Columbia University, plants which are not stressed by lack of water or nutrients are better able to withstand exposure to ultraviolet light.