SYNERGISTIC EFFECTS OF BIOCHAR AND ARBUSCULAR MYCORRHIZAL FUNGI ON ENHANCING ELYMUS ELYMOIDES GROWTH IN SALINE COASTAL SOIL

The study aimed to investigate the effect of biochar (BC) application on soil properties, Elymus elymoides growth, and mycorrhizal fungi diversity. Soil samples were treated with different rates of BC (1%, 2%, and 5%) and inoculated with arbuscular mycorrhizal fungi (AMF) or without AMF. The results indicated that the application of BC at 2% and 5% rates significantly increased the soil pH by 4.3% and 5.8%, respectively. Moreover, the exchangeable potassium (K) levels showed a significant increase in soils treated with BC, i.e., K levels increasing by 66.7% and 211.1% at 2% and 5% BC application rates, respectively. Conversely, sodium (Na) levels in the soil decreased significantly with increasing BC application rates. The soil organic carbon (SOC) levels showed a significant increase in the treatment groups compared to the control group, with increases of 150%, 177.78%, and 222.17% in BC1, BC2, and BC5, respectively. The cation exchange capacity (CEC) values also showed a significant increase in BC1, BC2, and BC5, with increases of 14.81%, 29.63%, and 44.44%, respectively, compared to that in the control group. In terms of Elymus elymoides growth, BC2 showed the highest percent increase in plant height with 54.83%, reaching 27.33 cm, while BC1 and BC5 also had significant increases of 13.23% and 49.35%, respectively, reaching 20 cm and 26.33 cm. However, when AMF was added to the treatment groups, the plant growth decreased for all groups, with BC2 showing the highest percentage decrease of 28.07%, reaching 19.67 cm. The results of the mycorrhizal fungi diversity showed that biochar application had a significant effect on the growth and diversity of mycorrhizal fungi, with the BC and BC + AMF groups showing the most inhibitory effects. The addition of biochar had a negative effect on all types of mycorrhizal fungi, with the species of important genera such as Rhizophagus, Glomus, Clarediogous, and Redochera decreasing to 39.67%, 22.67%, 18%, and 16.33%, respectively. However, the addition of biochar and AMF together led to an increase in the abundance of Rhizophagus to 62.67%, Glomus to 67.67%, Clarediogous to 38.33%, and Redochera to 16.67%.