Purpose To study the effects of soil sterilization and the fungicide benomyl on soybean growth and heavy metal accumulation.
Methods Taking polluted farmland soil as the substrate, indoor pot experiments were carried out to determine the growth indexes, chlorophyll content, antioxidant physiological indicators, content and accumulation of heavy metals lead (Pb), zinc (Zn), cadmium (Cd), cuprum (Cu) of soybean, and the available content of heavy metals in soil under the conditions of soil sterilization and benomyl application.
Results Compared with original soil, under soil sterilization treatment, the plant height, stem and leaf biomass, and fruit biomass of soybeans decreased by 21.00%, 43.92%, and 44.47%, respectively; but the root biomass increased by 56.57%. Soil sterilization and benomyl treatments significantly increased the soil available Pb content, by 160.62% and 179.00%, respectively; and significantly reduced soil available Zn content by 33.82% and 17.37%, respectively. Soil sterilization also significantly increased the contents of Zn and Cd, and the accumulation of Pb, Zn, Cd, and Cu in soybean roots, and significantly decreased the accumulation of Pb and Cu in soybean stems, leaves and fruits, and also increased the enrichment coefficient of Pb, Zn, and Cd. The application of benomyl significantly increased carotenoid and Pb content in stems, leaves, and roots, by 77.00%, 36.87%, and 12.43%, respectively; and significantly increased the accumulation of Pb in soybean stems and leaves; the enrichment coefficient and transport coefficient of Pb were increased significantly; but there was no significant effect on the soybean growth, antioxidant physiology, and other heavy metal accumulation.
Conclusion The complete elimination of soil microbes inhibits soybean growth and significantly reduce the plant’s ability to tolerate and accumulate heavy metals, indicating that soil microorganisms play a crucial role in soybean growth and heavy metal tolerance.
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