Arbuscular mycorrhizal fungi and humic substances increased the salinity tolerance of rice plants

Abstract

Salinity induces salt uptake by plant cells, which hinders plant growth and results in decreased agronomic crop yields. Humic substances (HSs) have been shown to be ecological agricultural alternatives to stimulate plant development under both normal and abiotic stress conditions. At the same time, arbuscular mycorrhizal fungi (AMF) provide nutrients and provide salinity tolerance through the osmotic balance between Na+ and K+. This study aimed to evaluate the effects of the combination of AMF and HSs on the growth of rice plants under salinity stress. The experiment was carried out in a greenhouse: Pots filled with sand were treated with a nutrient solution (as a control), 40 mg HS L−1 or 200 mM NaCl and inoculated with Acaulospora mellea, Glomus formosanum, Rhizoglomus clarum, or Glomus spp. The HSs and AMF stimulated biomass production and root growth compared to those of uninoculated plants. The leaf P content increased in the presence of HSs and AMF under stress conditions. The sodium concentration was higher in the shoots of plants not treated with HSs than in those of the control plants. The potassium concentration decreased in the shoots under saline conditions. HSs and AMF alone or in combination promoted mycorrhizal colonization, especially that of A. mellea. AMF and HSs stimulated plant growth, improved root morphological characteristics, and increased P accumulation in rice plants under salt-stress conditions. These results support the production of biofertilizers with protective effects for sustainable agriculture.