Abstract
Drought stress is one of the primary abiotic stresses that inhibits the rehabilitation of degraded rangelands in Saudi Arabia, however, studies on the ability of arbuscular mycorrhizal fungi (AMF) to improve stress tolerance are lacking. Panicum turgidum, (Poaceae) is widely distributed in the Sahara of Saudi Arabia and represents a relatively good source for crude protein as fodder. An experiment was conducted in pots to evaluate the ability of AMF to improve drought-stress tolerance in P. turgidum. Results indicated that drought stress reduced the growth of P. turgidum and affected AMF colonization by reducing the number of spores, arbuscules, vesicles, and mycelia. Inoculation of the soil with AMF significantly enhanced root growth and ameliorated the negative effects of drought stress. AMF upregulated the antioxidant system in P. turgidum which prevented the accumulation of hydrogen peroxide and thus reduced the rate of lipid peroxidation. In addition, AMF also enhanced the synthesis of indole acetic acid (IAA); thereby promoting growth under both normal and drought-stress conditions. In summary, soil inoculation with AMF improved drought stress tolerance in P. turgidum by enhancing the antioxidant system in host tissues.