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Journal of Desert Research ›› 2024, Vol. 44 ›› Issue (5): 23-28.DOI: 10.7522/j.issn.1000-694X.2024.00030

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Daily variations in chlorophyll fluorescence parameters of hypolithic cyanobacteria in desert region of the Hexi Corridor

Yidan Zhao1,2,4(), Tuo Chen1, Yang Liu1,2, Lu Zhang2,3,4, Yiyang Zhang2,3,4, Wei Zhang2,3, Gaosen Zhang2,3()   

  1. 1.State Key Laboratory of Cryospheric Sciences /, Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China
    2.Gansu Province Key Laboratory of Extreme Environmental Microbial Resources and Engineering /, Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China
    3.Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China
    4.University of Chinese Academy of Sciences,Beijing 100049,China
  • Received:2023-12-21 Revised:2024-02-12 Online:2024-09-20 Published:2024-10-15
  • Contact: Gaosen Zhang

Abstract:

Fewer studies have been conducted on changes in the photosynthetic activities of hypolithic microorganisms, with the majority of previous research concentrating on the microbial composition and distributional properties. The hour-by-hour daily variation characteristics of chlorophyll fluorescence parameters of three hypolithic cyanobacteria distributed in three different aridity levels of the Hexi Corridor were studied as experimental materials using the handy PEA plant efficiency meter over a 72-hour period. The results showed that the hypolithic cyanobacteria exhibited daily fluctuations in their maximum photochemical quantum yield (Fv /Fm) values, reaching a higher level at approximately 06:00 a.m. and 18:00-20:00 p.m., with the greatest values above 0.6. The Fv /Fm values were less than 0.1 at 12:00-14:00 at higher irradiance (>2 mW·cm-2), higher temperature (>30 ℃), and lower humidity (<12.5%) as a result of the environmental stress. Rainfall events, which may be related to the type of stone, soil, and rainfall amount in this area, caused significantly higher values of Fv /Fmfor hypolithic cyanobacteria in the North Gobi of Guazhou (GZ), with mean values fluctuating from 0.1 to 0.35, and smaller fluctuations of Fv /Fm in the Dacaotan of Jiayuguan (JYG), with mean values ranging from 0.1 to 0.19. This work exposes, to some extent, variations in photosynthetic activity of hypolithic cyanobacteria throughout a day and offers a theoretical foundation for the study of hypolithic microbial communities.

Key words: Hexi Corridor, hypolithic microorganisms, chlorophy Ⅱ fluorescence, cyanobacterial photosynthetic activity, daily variation

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