The parasitic plant Cistanche deserticola attaches to Haloxylon ammodendron,a perennial shrub with high tolerance to salinity and drought.However,little was known about the parasite-host relation between the two species.Effects of the parasite on chlorophyll a fluorescence and nutrient accumulation in the host plant (H.ammodendron) were investigated in the Taklimakan Desert.Some photosynthetic parameters of both host and non-host H.ammodendron plants were measured by in vivo chlorophyll a fluorescence technology in the field.The assimilating branches of host and non-host plants were collected and nutrient and inorganic ion contents were analyzed.The results from field experiments showed that the infection of C.deserticola reduced the non-photochemical quenching of the variable chlorophyll fluorescence (NPQ) and the potential maximum quantum yield for primary photochemistry (Fv/Fm) of the host.Compared with non-host plants,the host H.ammodendron had low nutrient,low inorganic ion contents (Na+ and K+) and low K+/Na+ ratios in the assimilating branches.It suggested that C.deserticola infection reduced the nutrient acquisition and caused damage to the photoprotection through thermal dissipation of the energy of the photosystem Ⅱ in the host,resulting in a decrease in the tolerance to salinity and high radiation.It was concluded that the attachment of the parasite plant (C.deserticola) had negative effects on the growth of its host.