Abstract: The effects of UV-B radiation on the growth of Ulva pertusa Kjellman spores were studied by experimental ecological methods. The results showed that the growth morphology of Ulva pertusa Kjellman spores was mainly rod shape and tadpole shape. The percentage of rod shape was 90.68%±2.50%. UV-B radiation could inhibit the growth of Ulva pertusa Kjellman spores, and the growth inhibition was more significant with the increased doses of UV-B radiation treatment. On the day 30, Ulva pertusa Kjellman seedling had emerged death under UV-B radiation, and the death rate was increased with the increased doses of UV-B radiation treatment. The chlorophyll a contents of Ulva pertusa Kjellman seedling were significantly decreased, while MDA contents were increased by UV-B radiation. Therefore, the reasons of Ulva pertusa Kjellman seedling growth inhibition and death were cell division, chlorophyll and cell membrane system damage.

Key words: UV-B radiation, Ulva pertusa Kjellman, spores, growth