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Change in effects of elevated ozone concentration on physiological characteristics of Brassica pekinensis leaves with prolonged exposure time
Received:October 06, 2022  
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KeyWord:O3 concentration;exposure time;OTC;Brassica pekinensis;physiological characteristics
Author NameAffiliationE-mail
GAO Yiqin College of Life Sciences, Hebei Normal University, Shijiazhuang 050016, China
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China 
 
WANG Xiaoke State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China  
WAN Wuxing College of Life Sciences, Hebei Normal University, Shijiazhuang 050016, China wan.wx1972@126.com 
FENG Meiqi College of Life Sciences, Hebei Normal University, Shijiazhuang 050016, China
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China 
 
ZHANG Danhong State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China  
GENG Chunmei Chinese Research Academy of Environmental Sciences, Beijing 100012, China  
YIN Baohui Chinese Research Academy of Environmental Sciences, Beijing 100012, China  
ZHANG Nan Chinese Research Academy of Environmental Sciences, Beijing 100012, China  
SONG Rui College of Life Sciences, Hebei Normal University, Shijiazhuang 050016, China  
LIU Ying College of Life Sciences, Hebei Normal University, Shijiazhuang 050016, China  
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Abstract:
      The objective of this study was to quantify the adverse interaction effects of increased near-surface ozone(O3)concentration and prolonged exposure time on physiological indices of Brassica pekinensis leaves based on open-top chamber(OTC)analysis. The responses of physiological indices of B. pekinensis leaves were measured to the following four O3 concentration levels:ambient environmental concentration(NF); environmental concentration + 40 nmol · mol-1(NF40); environmental concentration + 80 nmol · mol-1(NF80); and environmental concentration + 120 nmol·mol-1(NF120). The relationship between intercept and slope of the best-fit linear models was temporally assessed with respect to different observation times, and the following physiological indices of B. pekinensis were analyzed: chlorophyll(Chl), carotenoid(Car), soluble protein(SP), soluble sugar(SS), phosphoenolpyruvate carboxylase activity(PEPC), malondialdehyde(MDA), ascorbic acid(AsA), glutathione(GSH), total antioxidant capacity(T-AOC), and O3 exposure dose(AOT40). With the increased O3 concentration after 28-d cumulative fumigation, the Chl, Car, and SP contents declined by 19.09%, 30.45%, and 33.66%; 12.85%, 24.69%, and 27.78%; and 26.30%, 37.89%, and 38.16% in response to NF40, NF80, and NF120, respectively, relative to the NF control group(P<0.05). The contents of MDA, SS, GSH, AsA, and T-AOC rose by 31.11%, 33.42%, and 75.23%; 165.61%, 207.08%, and 306.00%; 78.30%, 89.08%, and 162.09%; 14.47%, 15.11%, and 92.35%; and 27.87%, 32.84%, and 42.61% in response to NF40, NF80, and NF120, respectively, relative to the NF control group. The increased O3 concentration decreased the photosynthetic pigment, increased the physiological injury, and induced the antioxidant ability of B. pekinensis leaves to resist O3 stress. With the prolonged O3 exposure time, the sensitivity of Chl, Car, SP, and MDA to O3 fell(P<0.05), while the sensitivity of SS, GSH, AsA, and TAOC to O3 did not change significantly. This shows that the effect intensity of O3 on the physiological indices of B. pekinensis leaves declined with the prolonged exposure time. The sensitivity of this vegetable species to O3 stress decreased with time. Overall, the high concentration of O3 fumigation for a long time reduced photosynthesis of B. pekinensis, improved its antioxidant capacity, and finally decreased its biomass, while its sensitivity to O3 stress decreased.