Effects Of Enhanced UV-B Radiation On The Growth And Photosythetic Characteristics Of Tomato Seedling

Lige'er87-5(the normal type tomato) and 2005066(the etiolation type tomato) were investigated under plastic greenhouse ambient conditions with enhancd UV-B radiation with the intensities of 0w/m2(CK),0.5w/m2 respectively. The duration of UV-B treatment were sevenhours Per day,it starts from 9Am to 16Pm.The effects of UV-B radiation on the photosynthetic characteristics and growth of tomato seedlings were studied. The main results are as follows:1.The growth height,stem diameter and leaf size of the two kinds of tomato seedlings were inhibited by the enhancd UV-B radiation. The results showed that the etiolation type were more sensentive than the normal type.2.The results indicated that the changes of antioxidant systems in the two kinds of tomato cultivars were distinct. This may be responsible for their different adaptive responses to the stress, the normal type'adaptivity were better than the etiolation type.3.The contents of flavonoid was increased considerably under enhancd UV-B radiation.The changes of the etiolation type were more distinctly.4.Fv/Fm, Fv/F0,ФPSⅡ, Fv′/Fm′and qP reduced considerably when plants were treated under enhancd UV-B radiation, but the etiolation type was inhibited distinctly. qN increased under the enhanced UV-B radiation, but the common type increased distinctly, which could dissipate the excess excitation energy and protect photosynthetic apparatus.5.The contents of chlorophyll,Pn,Ci,Gs were decreased under the enhanced UV-B radiation,the changes of the etiolation type were more distinctly. It indicated that the photosynthetic efficiency of the etiolation type decreased distinctly.