Objective Research on the response process of physiological parameters of desert plants to natural environment fluctuations can better understand and predict the impact of climate change on desert ecosystems.
Method We conducted in situ field measurements of chlorophyll fluorescence for three desert shrub species (Artemisia ordosica, Salix psammophila and Hedysarum mongolicum) to explore the responses of photosystem II (PSII) maximum quantum yield (Fv / Fm), photochemical efficiency (ΦPSII) and non-photochemical quenching (NPQ) to environmental factors, in order to understand the PSII photosynthetic physiology and its photoprotection mechanism of desert shrubs in arid environment.
Result Under water stress (soil water content < 0.08 m3/m3), Fv / Fm and Φ PSII of three kinds of desert shrubs were reduced and NPQ increased (P < 0.01). The Fv / Fm of S. psammophila was lower than that of A. ordosica and higher than H. mongolicum (P < 0.01). The ΦPSII of H. mongolicum was lower than both A. ordosica and S. psammophila (P < 0.01). The ΦPSII and NPQ for three typical desert shrubs presented a clear daily variation with photosynthetic active radiation (PAR), and also were affected by air temperature (Ta), relative humidity (RH) and vapor pressure difference (VPD). Three shrub species resisted drought stress through heat dissipation mechanism, but had different degrees. The Fv / Fm of A. ordosica can be restored to an appropriate value of about 0.75 through self-regulation of heat dissipation, and its reaction center damage was recoverable. H. mongolicum was greatly affected by drought stress, and its photoprotective response of heat dissipation was sensitive.
Conclusion A. ordosica can be considered as the first choice for vegetation restoration in arid areas, S. psammophila is the second and H. mongolicum is not recommended. The activity of PSII reaction center is characterized by changes in chlorophyll fluorescence parameters, which can fully reflect the response strategy of desert shrubs to environmental fluctuations, and can be used as an important means to explore the response of desert plants in arid and semi-arid areas to environmental changes.