生物炭、磷及AMF对Cd胁迫下柳枝稷生长及土壤性质的影响

This research investigated the effects of phosphorus, biochar addition and arbuscular mycorrhizal fungi (AMF) inoculation on the Cd tolerance of switchgrass. A pot experiment was conducted comprising four treatments: CK, 4.5% biochar (B), 60 mg·kg^-1 phosphorus (P₆₀), 4.5% biochar+60 mg·kg^-1 phosphorus (B+P₆₀), with or without AMF inoculation. Measurements made included plant growth, mineral concentration, Cd concentration, soil pH, available P and acid phosphatase, and forms of Cd present in the soil. It was found that P addition significantly increased root colonization, and the colonization reached 56.9% with the P₆₀ treatment. Compared with CK, B, P₆₀ and B+P₆₀ treatments had no significant effects on plant height, leaf SPAD and biomass of switchgrass. The plant height, leaf SPAD and biomass of switchgrass increased significantly with AMF inoculation, but there were no significant differences among the treatments after AMF inoculation. Except for higher Se and Cd in shoot concentrations in P₆₀ and B+P₆₀ treatments, compared to CK, there were no significant differences between B, P₆₀ and B+P₆₀ treatments and the CK treatment for P, Se and Cd concentrations in shoot tissues. After AMF inoculation, the contents of Se and Cd under CK and B treatments in plants with AMF present were higher than those in plants uninoculated with AMF, and the concentrations of Cd in shoots of plants in the B+AM treatment were significantly higher than those of other treatments. However, the shoot concentrations of Se and Cd in plants in the P₆₀ treatment were lower than those plants with no AMF present. In addition, the root Cd concentrations of B and B+P₆₀ treatments were significantly higher than those of CK and P₆₀ treatments, soil available P contents were higher than those of CK, and soil acid-extracted Cd concentrations were lower than those of CK and P₆₀ treatments regardless of AMF inoculation status. The soil residual Cd concentrations of CK, B and B+P₆₀ treatments with AMF inoculation were higher than corresponding non-inoculated treatments, but the residual Cd contents for the P₆₀ treatment was lower than that of corresponding uninoculated treatment. In summary, B or B+P₆₀ treatments increased the root Cd and soil available P concentrations, reduced the soil acid-extracted Cd contents;Combined with AMF, B or B+P₆₀ treatment increased switchgrass biomass, shoot Se and Cd content, and increased soil residual Cd concentrations. Therefore, AMF inoculation of plants combined with biochar or biochar+phosphorus soil additions can increase the biomass and Cd uptake of switchgrass and reduce the soil Cd bio-availability. These findings are applicable to remediation of heavily Cd contaminated soils. © 2021, Editorial Office of Acta Prataculturae Sinica. All rights reserved.

Effects of biochar,phosphorus addition and AMF inoculation on switchgrass growth and soil properties under Cd stress

This research investigated the effects of phosphorus, biochar addition and arbuscular mycorrhizal fungi （AMF） inoculation on the Cd tolerance of switchgrass. A pot experiment was conducted comprising four treatments： CK, 4.5% biochar （B）, 60 mg·kg^-1 phosphorus （P₆₀）, 4.5% biochar+60 mg·kg^-1 phosphorus （B+P₆₀）, with or without AMF inoculation. Measurements made included plant growth, mineral concentration, Cd concentration, soil pH, available P and acid phosphatase, and forms of Cd present in the soil. It was found that P addition significantly increased root colonization, and the colonization reached 56.9% with the P₆₀ treatment. Compared with CK, B, P₆₀ and B+P₆₀ treatments had no significant effects on plant height, leaf SPAD and biomass of switchgrass. The plant height, leaf SPAD and biomass of switchgrass increased significantly with AMF inoculation, but there were no significant differences among the treatments after AMF inoculation. Except for higher Se and Cd in shoot concentrations in P₆₀ and B+P₆₀ treatments, compared to CK, there were no significant differences between B, P₆₀ and B+P₆₀ treatments and the CK treatment for P, Se and Cd concentrations in shoot tissues. After AMF inoculation, the contents of Se and Cd under CK and B treatments in plants with AMF present were higher than those in plants uninoculated with AMF, and the concentrations of Cd in shoots of plants in the B+AM treatment were significantly higher than those of other treatments. However, the shoot concentrations of Se and Cd in plants in the P₆₀ treatment were lower than those plants with no AMF present. In addition, the root Cd concentrations of B and B+P₆₀ treatments were significantly higher than those of CK and P₆₀ treatments, soil available P contents were higher than those of CK, and soil acid-extracted Cd concentrations were lower than those of CK and P₆₀ treatments regardless of AMF inoculation status. The soil residual Cd concentrations of CK, B and B+P₆₀ treatments with AMF inoculation were higher than corresponding non-inoculated treatments, but the residual Cd contents for the P₆₀ treatment was lower than that of corresponding uninoculated treatment. In summary, B or B+P₆₀ treatments increased the root Cd and soil available P concentrations, reduced the soil acid-extracted Cd contents; Combined with AMF, B or B+P₆₀ treatment increased switchgrass biomass, shoot Se and Cd content, and increased soil residual Cd concentrations. Therefore, AMF inoculation of plants combined with biochar or biochar+phosphorus soil additions can increase the biomass and Cd uptake of switchgrass and reduce the soil Cd bio-availability. These findings are applicable to remediation of heavily Cd contaminated soils.