Factors Limiting Photosynthetic Recovery in Sweet Pepper Leaves After Short-Term Chilling Stress Under Low Irradiance |
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Authors: | Li X-G Wang X-M Meng Q-W Zou Q |
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Institution: | (1) College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, 271018, P. R. China;(2) High-Tech Research Center, Crop Institute, Shandong Academy of Agricultural Sciences, Ji'nan, Shandong, 250100, P. R. China;(3) College of Population, Resources and Environment, Shandong Normal University, Ji'nan, Shandong, 250014, P. R. China;(4) College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, 271018, P. R. China, e-mail |
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Abstract: | The effects of chilling treatment (4 °C) under low irradiance, LI (100 mol m–2 s–1) and in the dark on subsequent recovery of photosynthesis in chilling-sensitive sweet pepper leaves were investigated by comparing the ratio of quantum yields of photosystem (PS) 2 and CO2 assimilation, PS2/ CO2, measured in normal air (21 % O2, NA) and low O2-air (2% O2, LOA), and by analyzing chlorophyll (Chl) a fluorescence parameters. Chilling treatment in the dark had little effect on Fv/Fm and PS2/ CO2, but it caused the decrease of net photosynthetic rate (P
N) under saturating irradiance after 6-h chilling treatment, indicating that short-term chilling alone did not induce PS2 photoinhibition. Furthermore, photorespiration and Mehler reaction also did not obviously change during subsequent recovery after chilling stress in the dark. During chilling treatment under LI, there were obvious changes in Fv/Fm and PS2/ CO2, determined in NA or LOA. Fv/Fm could recover fully in 4 h at 25 °C, and PS2/ CO2 increased at the end of the treatment, as determined in both NA and LOA. During subsequent recovery, PS2/ CO2 in LOA decreased faster than in NA. Thus the Mehler reaction might play an important role during chilling treatment under LI, and photorespiration was an important process during the subsequent recovery. The recovery of PN under saturating irradiance determined in NA and LOA took about 50 h, implying that there were some factors besides CO2 assimilation limiting the recovery of photosynthesis. From the progress of reduced P700 and the increase of the Mehler reaction during chilling under LI we propose that active oxygen species were the factors inducing PS1 photoinhibition, which prevented the recovery of photosynthesis in optimal conditions because of the slow recovery of the oxidizable P700. |
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Keywords: | Capsicum chilling chlorophyll fluorescence Mehler reaction P700 photoinhibition photorespiration photosystem 2 |
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