Salinity effects on arbuscular mycelium network-mediated performance of Saltcedar and Camelhorn seedlings

Abstract

Arbuscular mycorrhizal fungi are important soil microorganisms that form arbuscular mycelium networks (AMN) and promote plant growth. However, reports on AMN effects on growth and physiological characteristics of desert plants under salinity are scarce. Here, we aimed to investigate the effects of salinity on AMN-mediated growth, photosynthesis, and metabolism of Saltcedar (Tamarix ramosissima) and Camelthorn (Alhagi sparsifolia) seedlings. Three salt treatments (0 %, 0.4 %, and 0.8 %, S1, S2, and S3, respectively), and two mycelial transfer distances (15 and 30 cm, L1 and L2, respectively), were tested on seeds planted in AMF-inoculated/uninoculated soil. At S1, mycorrhizal colonization promoted aboveground biomass of Saltcedar by 23.6 % (L1) and 21.8 % (L2) compared to non-inoculated plants, with chlorophyll a content elevated by 18.9 % (L1) and 17.5 % (L2), and SOD activity increased by 12.3 % (L1) and 11.8 % (L2) regardless of distance. For Camelthorn under S1, belowground biomass increased by 32.1 % (L1) and 30.5 % (L2), root length was enhanced by 27.5 % (L1) and 23.2 % (L2), and root/shoot ratio was 14.86 % higher under L1 than L2. Mycorrhizal colonization had no significant effect on F0 or Fm values of Saltcedar, nor Fm values of Camelthorn under S2 +L1. At S2+L1, AMF inoculation significantly reduced Fo values of Saltcedar by 4.5 % and increased Fm values of Camelthorn by 12.5 %. Neither growth nor physiological indexes differed between species in L2 under S2. Photosynthesis, antioxidant and osmotic regulation ability, and salt tolerance significantly improved in Saltcedar upon mycorrhizal colonization under low salinity and long distance, with chlorophyll fluorescence parameter Fv/Fm increased by 5.0 % (L1) and 4.8 % (L2). Meanwhile, root/shoot ratio and root morphological indexes improved in Camelthorn, which survived and continued to grow.