a study of uv-c and plant growth regulators effects on plantlets of aloe vera line.

background & aim: effects of ultra violet spectrum on plants due to their obligatory requirement for sunlight for survival are unavoidable. direct effects of uv on plant growth and development are generally negative and usually they use many different defense mechanisms to acclimate and protect themselves. material & methods: the present research for the first time was conducted to investigate the destructive, target or even possible constructive effects of ultraviolet-c (100-280 nm) on in vitro plantlets of aloe vera and changes of these effects under different concentrations of plant growth regulators of media cultures. aloe was selected because it is one of the most important subtropical medicinal plants and normally it is exposed to uv in its original growing regions. treatments were media culture in four stages and uv-c in two stages (0 and 40 mwcm-1). in vitro plants were cultured on four different media in six replications. three replications of them were exposed one hour per day with uv-c for one month. results & discussion : our results showed that longest plantlets, highest number of roots and longest roots formed on the media contain 1.5 mgl-1iba and highest number of shoots on the media contain 1.5 mgl-1iba and 1 mgl-1 ba.  conclusion: uv-c has significantly reduced the length of roots and shoots root number but increased the shoot number.