Stress tolerance of Xerocomus badius and its promotion effect on seed germination and seedling growth of annual ryegrass under salt and drought stresses

Comparative evaluations were conducted to assess the effects of different pH levels, NaCl-induced salt stress, and PEG-induced drought stress on the mycelial growth of Xerocomus badius. The results showed that X. badius mycelium grew well at a wide pH range of 5.00 ~ 9.00. Although the mycelium remained viable, mycelial growth of X. badius was significantly inhibited with increasing salt and drought stresses. Furthermore, a soilless experiment in Petri dishes was performed to investigate the potential of X. badius to induce beneficial effects on seed germination and seedling growth of annual ryegrass (Lolium multiflorum Lam.) under salt and drought stresses. Seed priming with X. badius enhanced the seedling growth of L. multiflorum Lam. under NaCl-induced salt stress and PEG-induced drought stress. However, X. badius did not significantly improve the seed germination under non-stress and mild stress conditions. It suggested that X. badius inoculation with seeds was not essential for seed germination under non-stress and mild stress conditions, but contributed highly to seedling growth under severe stress conditions. Therefore, seed priming with X. badius on ryegrass could be an effective approach to enhance plant tolerance against drought and salt stresses. X. badius could be a good candidate for the inoculation of ectomycorrhizal plants cultivation programs in mild saline and semiarid areas.