Effects of water stress and nitrogen supply on leaf gas exchange and fluorescence parameters of <Emphasis Type="Italic">Sophora davidii</Emphasis> seedlings |
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Authors: | F Z Wu W K Bao F L Li N Wu |
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Institution: | (1) Chengdu Institute of Biology, The Chinese Academy Sciences, 610041 Chengdu, P.O. Box 416, P.R. China;(2) Graduate University of the Chinese Academy of Sciences, 100039 Beijing, P.R. China |
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Abstract: | Two-month-old seedlings of Sophora davidii were subjected to a randomized complete block design with three water (80, 40, and 20 % of water field capacity, i.e. FC80, FC40, and FC20) and three N supply N0: 0, Nl: 92 and Nh: 184 mg(N) kg−1(soil)] regimes. Water stress produced decreased leaf area (LA) and photosynthetic pigment contents, inhibited photosynthetic
efficiency, and induced photodamage in photosystem 2 (PS2), but increased specific leaf area (SLA). The decreased net photosynthetic
rate (P
N) under medium water stress (FC40) compared to control (FC80) might result from stomatal limitations, but the decreased P
N under severe water deficit (FC20) might be attributed to non-stomatal limitations. On the other hand, N supply could improve photosynthetic capacity by increasing
LA and photosynthetic pigment contents, and enhancing photosynthetic efficiency under water deficit. Moreover, N supply did
a little in alleviating photodamages to PS2 caused by water stress. Hence water stress was the primary limitation in photosynthetic
processes of S. davidii seedlings, while the photosynthetic characters of seedlings exhibited positive responses to N supply. Appropriate N supply
is recommended to improve photosynthetic efficiency and alleviate photodamage under water stress. |
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Keywords: | adaptation chlorophyll fluorescence intercellular CO2 concentration leaf area net photosynthetic rate respiration rate specific leaf area stomatal conductance water use efficiency |
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