Inorganic or organic amendments facilitated the phytostabilisation potential of Robinia pseudoacacia L. under the heavy metal-contaminated soil: plant growth, heavy metal immobilization, and microbial co-occurrence network
Description
Robinia pseudoacacia L., a pioneer woody legume plant, had been confirmed as a candidate plant for the phytostabilisation of heavy metal contaminated soil. However, high levels of heavy metals in mining areas produced an adverse on plant growth. In this study, five types of inorganic or organic amendments, namely limestone (SH), hydroxyapatite (LH), biochar (SW), calcium magnesium phosphate fertilizer (GM), and organic fertilizer (YJ), were selected to assisted with R. pseudoacacia L. to improve plant growth, and further enhance the phytostabilisation potential in mining areas. The results indicated that both inorganic and organic amendments could promote the growth of R. pseudoacacia L., reduce Cd and Pb uptake in plant, immobilize the bioavailability of Cd and Pb in the soil, and change the co-occurrence network of soil microbial community structure. The growth of R. pseudoacacia L. was significantly increased under the application of inorganic or organic amendments, especially for the application of LH was significantly (p< 0.05) increased by 57.2%-56.4%. Meanwhile, the diethyltriamine pentaacetic acid (DTPA) extractable Cd and Pb contents in soil with the application of LH were decreased by 16.0%-16.3% and 8.3%-8.6% relative to the control, and the Cd and Pb content in R. pseudoacacia L. roots was also significantly (p< 0.05) reduced by 35.9%-76.1% and 26.3%-74.3%, respectively. Five types of inorganic or organic amendments could significantly change the microbial community structure of R. pseudoacacia L. rhizosphere soil, especially for LH. Network analysis indicated that R. pseudoacacia L. associated with inorganic amendments could promote the stability and complexity of the microbial network in the contaminated soil. These results suggested that inorganic amendments might promote plant growth and improve the complexity of rhizosphere microbial network, thereby enhancing the adaptability of R. pseudoacacia L. for the phytostabilisation of mining areas.