Sandstorms damage the photosynthetic activities of Haloxylon ammodendron seedlings

Abstract

Haloxylon ammodendron is a preferred shrub species for buffering against wind and fixing sand in arid sandy areas of northwest China. To determine whether sandstorms cause damage to H. ammodendron seedlings, we investigated the effects of wind-blown sands on the photosynthetic function of H. ammodendron by simulating sand-carrying wind in the wind tunnel. The results showed that photosystem II (PSII) non-photochemical quenching (NPQ) was sensitive to wind erosion, and sustained blowing of sand-carrying winds enhanced NPQ reduction. The rapidly relaxing quenching NPQf made up the majority component of NPQ; the NPQf/NPQ ratio was approximately 64.4% in the sand-free wind group and nearly 56.2% in the sand-carrying wind group. The distribution of the quantum efficiency of the excitation energy indicated that the relative proportions of the quantum yield of PSII photochemistry ΦPSII, the quantum yield of quenching due to light-induced ΦNPQ, and non-light-induced ΦNO were influenced by both wind erosion and light intensity; the sand-carrying wind resulted in a relative decrease in ΦNPQ and a corresponding increase in ΦNO. The maximum quantum efficiency of PSII photochemistry Fv/Fm was relatively stable in the sand-free wind group, with an average value of approximately 0.81. Compared to sand-free wind, sand-carrying winds caused remarkable decreases in Fv/Fm. Light intensity was the main factor affecting ΦPSII, ΦNPQ, and relative electron transport rate (rETR); there was no interaction effect between the duration of sand-carrying wind and light intensity. Taken together, wind-blown sands cause irreversible damage to the photosynthesis of H. ammodendron seedlings, which is the main factor restricting population regeneration in shelterbelts.