Physiological responses of 2-year-old Acer davidii seedlings to short-term enhanced UV-B radiation

Abstract

Abstract: At the Maoxian Ecological Experimental Station of Chinese Academy of Sciences in northwest Sichuan Province,2-year-old native maple（Acer davidii） seedlings were potted outdoors with enhanced UV-B radiation（280～320 nm） of 0.27 W·m^-2(7.7 kJ·m^-2·d^-1),which was approximated to the predicted enhanced UV-B reaching the earth surface when stratosphere ozone was depleted by 15% in the local area,with the control plant received ambient UV-B.The gas exchange index and chlorophyll fluorescence,and the contents of chlorophyll and UV-absorbing compounds were examined after 50 days of the radiation.The results showed that enhanced UV-B radiation significantly lowered the maximal net photosynthetic rate（CK=6.214,TR=4.452）,raised the dark respiration rate（CK=0.413,TR=1.295） and light compensation point（CK=21.629,TR=59.861）,but had little effect on quantum yield（CK=0.021,TR=0.032）.Under enhanced UV-B radiation,the diurnal changes in net photosynthetic rate,water use efficiency,quantum efficiency of photosystem Ⅱ centers（F_v/F_m）,and quantum yield of photosystem Ⅱ photochemistry(Φ_PSП) were reduced,chlorophyll a,total chlorophylls,and chlorophyll a/b（CK=16.23,5.39,TR=13.17,4.93） were also markedly reduced,but chlorophyll b remained nearly unchanged.Contrary to the previous studies,enhanced UV-B radiation decreased the content of UV-absorbing compounds（CK=0.87,TR=0.79） in 2-year-old Acer davidii seedling leaves,indicating that the measurement of leaf UV-B absorbing compounds didn't necessarily provide a good indicator of plant tolerance to UV-B.It could be concluded that enhanced UV-B radiation had some inhibitory effects on the photosynthesis of Acer davidii seedlings.Long-term researches are necessary to confirm this conclusion.

Key words: UV-B radiation, Acer davidii, Physiological response

CLC Number:

Q945

ZUO Yuanyuan, LIU Qing, LIN Bo, HE Hai. Physiological responses of 2-year-old Acer davidii seedlings to short-term enhanced UV-B radiation[J]. Chinese Journal of Applied Ecology, 2005, 16(9): 1682-1686.

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