Abstract: Tamarix ramosissma and Alhagi sparsifolia are two mycorrhizal plant species in the desert riparian forests of the lower reaches of Tarim River, which are strongly affected by salt stress during seedling growth. To investigate the effects of  arbuscular mycorrhizal fungi (AMF) on the growth and characteristics of chlorophyll fluorescence of the seedlings of both species under salt stress, a pot experiment was conducted with four treatments, including control (CK), AMF inoculation (+AMF), salt stress (+S), and AMF inoculation under salt stress (+S+AMF). We measured AMF colonization of seedling roots (colonization rate and intensity), growth characteristics (plant height, basal stem, crown width, root length, root surface area, average root diameter, root volume, and root tip number), chlorophyll content (chlorophyll a and b, and total chlorophyll), and chlorophyll fluorescence parameters (minimum fluorescence F_o, maximum fluorescence F_m, photochemical quenching factor qP, non-photochemical quenching factor NPQ, maximum photochemical efficiency F_v/F_m, and potential activity F_v/F_o). The results showed that salt stress significantly inhibited the colonization rate, apparent growth index, chlorophyll content and chlorophyll fluorescence parameters of seedlings of both species (P < 0.05). Inoculation with AMF promoted the aboveground and belowground growth of the seedlings, increased the chlorophyll content and F_o, F_m, and qP values, reduced the magnitude of changes in the NPQ values and salt stress time on F_v/F_m and F_v/F_o, and improved the characteristics of chlorophyll fluorescence to attenuate the damage of salt stress on seedlings. AMF was more effective in mitigating the effect of salt stress on A. sparsifolia seedlings than that on T. ramosissma. Therefore, AMF can promote the growth of seedlings under salt stress by increasing root growth, chlorophyll content, and chlorophyll fluorescence properties in host plants. Such effects vary with different life types of plant species.

Key words: arbuscular mycorrhizal fungi, salt stress, Tamarix ramosissma, Alhagi sparsifolia, root system, chlorophyll fluorescence