[Effects of Exogenous NO Combined with EDDS on Growth and Cd Accumulation of <i>Bidens pilosa</i> under Soil Cd Stress Conditions].

Under 40 mg·kg^-1 Cd stress, pot experiments were conducted to investigate the effects of 0.05, 0.10, 0.20, and 0.30 mmol·L^-1 sodium nitroprusside （SNP） and 0.50, 1.00, and 1.50 mmol·L^-1 [S,S]-ethylenediamine disuccinic acid （EDDS） on the growth, metabolism, and Cd accumulation of <i>Bidens pilosa</i> seedlings. The results showed that compared with those of the control group （without SNP and EDDS）, different concentrations of SNP or EDDS single treatment could significantly increase the plant height, root length, fresh weight, and dry weight of aboveground and underground parts of <i>B. pilosa</i> and effectively increase the photosynthetic pigment content and Cd content in the aboveground and underground parts. The combined treatment of different concentrations of SNP and EDDS could effectively promote the growth of <i>B. pilosa</i>, and some growth indices and Cd accumulation indices were higher than those of the single treatment of SNP and EDDS at the same concentration. Among them, the 0.20 mmol·L^-1 SNP + 1.00 mmol·L^-1 EDDS composite treatment had the following effects： ① The treatment significantly promoted the biomass of <i>B. pilosa</i> and increased the plant height and fresh and dry weight of aboveground and underground parts by 39.47%, 142.32% and 267.63%, and 377.63% and 304.55%, respectively. ② It significantly improved the remediation effect of <i>B. pilosa</i> on Cd-contaminated soil, and the Cd content, enrichment coefficient, remediation efficiency, and transport coefficient of aboveground and underground parts of <i>B. pilosa</i> were increased by 91.22% and 81.51%, 101.71%, and 91.37%, 641.67%, and 5.14%, respectively, and the Cd content and enrichment coefficient of aboveground parts were significantly higher than those of underground parts. ③ The treatment also significantly increased the Cd content in subcellular fractions of <i>B. pilosa</i>, the Cd content in the cell wall and soluble part was higher than that in the organelle and mitochondrial parts, and the Cd content in subcellular fractions of the aboveground part was also higher than that of the underground part. The comprehensive analysis showed that the application of appropriate concentrations of SNP and EDDS could effectively promote the growth and Cd accumulation of <i>B. pilosa</i> under soil Cd stress, which is helpful for <i>B. pilosa</i> to enhance Cd resistance and detoxification through the cell wall barrier and vacuolar compartmentation. According to the experimental results, the combination of 0.20 mmol·L^-1 SNP + 1.00 mmol·L^-1 EDDS can be used to enhance the remediation efficiency of <i>B. pilosa</i> on Cd-contaminated soil.