Effects of groundwater depth variation on photosynthesis and photoprotection of <Emphasis Type="Italic">Elaeagnus angustifolia</Emphasis> L. |
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Authors: | Chang-Ming Zhao Gen-Xuan Wang Xiao-Ping Wei Jian-Ming Deng Dong-Liang Cheng |
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Institution: | (1) Key Laboratory of Arid and Grassland Ecology of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, PR China;(2) College of Life Sciences, Zhejiang University, Hangzhou, 310027, PR China |
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Abstract: | Physiological and photosynthetic responses were investigated at three different depths of groundwater (DGW: 1.4, 2.4, and
3.4 m) in Elaeagnus angustifolia L., a locally adapted tree to the arid region in northwest China. Predawn leaf water potential and chlorophyll content declined
gradually with the increasing DGW, whereas there was little effect on predawn variable-to-maximum chlorophyll fluorescence
ratio F
v/F
m and leaf carotenoid compositions (xanthophyll cycle pool, neoxanthin, lutein, and β-carotene). Net photosynthetic rate (P
n), quantum yield of PSII electron transport (ΦPSII), stomatal conductance (Gs), and intercellular CO2 concentration (Ci) declined obviously; however, P
n decreased more than ΦPSII at deeper DGW. The photoinhibition of PSII at all three DGW occurred at midday in summer and increased as DGW increased.
The ΔpH-dependent thermal dissipation and the level of de-epoxidation of the xanthophyll cycle at all three DGW reached their
maxima at midday with the increase of light intensity. However, the fraction of functional PSII and light intensity at deeper
DGW (2.4, 3.4 m) showed a negative correlation. This correlation suggested that most of violaxanthin was converted into zeaxanthin
at midday, and the reversible inactivation of partial PSII reaction centers took place at deeper DGW. These results together
suggest that both the xanthophyll cycle-dependent thermal dissipation and the reversible inactivation of partial PSII might
have played important roles in avoiding the excess light-induced energy damage in leaves of this tree species at deeper DGW. |
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Keywords: | Elaeagnus angustifolia L Photoinhibition Reversible inactivation of PSII Xanthophylls Photoprotection |
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