Effects of cerium on membranous protective enzymes in rape seedlings exposed to two levels of enhanced ultraviolet-B radiation(UV-B,280～320 nm) was studied by hydroponics in the laboratory.

The response of defense enzyme and photosynthesis in rape seedling t o combined stress of elevated ultraviolet-B radiation (UV-B, 280～320nm) and a cid rain was studied under lab conditions.

In the experi ment, the rape seedlings were separated to three groups except control group.

The results showed that the grow th indexes of rape seedlings on main r oot length,root vol-ume,fresh weight,dry weight,and pl ant height,stemheight,leaf number,leaf area,leaf fresh weight,leaf dry weight,stemfresh weight and stemdry weight all obviou sly reduced under UV -B radiation str ess.

It was studied that effects of soybean isoflavones on some physiological Characteristics of the rape seedlings with simulated acid rain stress, probing into if soybean isoflavones would improve the rape seedlings growth withstanding simulated acid rain stress.

Effect of Ce on growth and photosynthesis of rape seedlings under elevated ultraviolet-B radiation (UV-B, 280～320 nm) was studied.

The results demonstrate that the cyanide-resistant respiration exists in different organs of bean seedlings, and the ρV_(alt) in true leaf was the highest, that in cotyledon the next, and hypocotyl ρV_(alt) was the lowest.

The result showed that retardant treatment could restrict remarkably the growth of Chinese cabbage seedling.