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We investigated the photosynthetic characteristics of Chorispora bungeana under conditions of drought stress caused by different concentrations of polyethylene glycol-6000 (PEG; 0, 5, 20, and 40%) and various concentrations of exogenous glycine (0, 5, 10, and 20 mM) with 20% PEG. We showed that moderate and severe drought stress of PEG reduced the chlorophyll (Chl) content (both Chl a and b), maximal quantum yield of PSII photochemistry (F v /F m ), actual photochemical efficiency of PSII in light (Y II ), and quantum yield of regulated energy dissipation (Y NPQ ), while Chl a/b and quantum yield of nonregulated energy dissipation (Y NO ) increased. The low and moderate drought stress increased Mg 2+ and Fe 3+ contents, while a decrease in Mg 2+ and Fe 3+ was found under severe drought stress. Compared to sole PEG stress, the addition of exogenous 10 mM glycine increased Chl, Mg 2+ and Fe 3+ contents, F v /F m , Y II , and Y NPQ , and reduced Y NO . On the contrary, 20 mM glycine showed an opposite effect, except for Y NO . Our results proved that Chl contents and fluorescence parameters are reliable indicators for drought tolerance of C. bungeana. We suggest that a proper glycine content can relieve the effect of drought stress on C. bungeana.

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