Studies On The Responses Of Desert Algae To Ultraviolet Radiation And The Algal Crust Formation Under Field Conditions

Scytonema javanicum (Kütz.) Born et Flah, Microcoleus vaginatus Gom. and Phormidium tenue (Menegh.) Gom., isolated from desert microbial crusts by Dr. C.X. HU, were used as experimental materials. Effects of UV radiation on the morphology and ultrastructure of S. javanicum, and on the physiological and biochemical characteristics of S. javanicum and M. vaginatus were studied. Those that the mechanism of oxidative stress by UV-B radiation, the optimized cultivation conditions for mass culture, the implantation and development of man-made algal crust in field and physical-chemical properties of artificial algal crust were also studied. The main results were shown as the followings:After exposure to an enhanced UV-B radiation, both morphology and ultrastructure of S. javanicum changed, the diameter and volume of cells diminished, biomass decreased and population color got yellowing in the culture. The laminar structure became more visible, and increasing number of polysaccharides and fat granules were displayed.Under UV-A radiation, changes in Fv/Fm of S. javanicum had such a trend: firstly decreased, then increased even exceeded the controls in 48hrs. To M. vaginatus, the Fv/Fm had a slightly decrease. These changes suggested the photosynthesis of algae was somewhat related with UV-A radiation. Undeer 0.48...