Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan.
Department of Isotope Biogeochemistry, Helmholtz - Center for Environmental Research-UFZ, Leipzig, Germany.
Environ Sci Pollut Res Int. 2020 Dec;27(35):44528-44539. doi: 10.1007/s11356-020-10372-4. Epub 2020 Aug 8.
Lead (Pb) is considered an important environmental contaminant due to its considerable toxicity to living organisms. It can enter and accumulate in plant tissues and become part of the food chain. In the present study, individual and combined effects of Bacillus sp. MN-54 and phosphorus (P) on maize growth and physiology were evaluated in Pb-contaminated soil. A pristine soil was artificially contaminated with two levels of Pb (i.e., 250 and 500 mg kg dry soil) and was transferred to plastic pots. Bacillus sp. MN-54 treated and untreated maize (DK-6714) seeds were planted in pots. Recommended doses of nutrients (N and K) were applied in each pot while P was applied in selective pots. Results showed that Pb stress hampered the maize growth and physiological attributes in a concentration-dependent manner, and significant reductions in seedling emergence, shoot and root lengths, fresh and dry biomasses, leaf area, chlorophyll content, rate of photosynthesis, and stomatal conductance were recorded compared with control. Application of Bacillus sp. MN-54 or P particularly in combination significantly reduced the toxic effects of Pb on maize. At higher Pb level (500 mg kg), the combined application effectively reduced Pb uptake up to 42.4% and 50% by shoots, 30.8% and 33.9% by roots, and 18.4% and 26.2% in available Pb content in soil after 45 days and 90 days, respectively compared with that of control. Moreover, the use of Bacillus sp. MN-54 significantly improved the P uptake by maize plants by 44.4% as compared with that of control. Our findings suggest that the combined use of Bacillus sp. MN-54 and P could be effective and helpful in improving plant growth and Pb immobilization in Pb-contaminated soil.
铅（Pb）被认为是一种重要的环境污染物，因为它对生物体具有相当大的毒性。它可以进入并积累在植物组织中，并成为食物链的一部分。在本研究中，评估了 Bacillus sp. MN-54 和磷（P）对受 Pb 污染土壤中玉米生长和生理的单独和联合作用。将原始土壤人工污染为两个 Pb 水平（即 250 和 500 mg kg 干土），然后转移到塑料盆中。在盆中种植经 Bacillus sp. MN-54 处理和未处理的玉米（DK-6714）种子。在每个盆中都施加了推荐剂量的养分（N 和 K），而在选择性盆中施加了 P。结果表明，Pb 胁迫以浓度依赖的方式阻碍了玉米的生长和生理特性，与对照相比，幼苗的出现，茎和根的长度，鲜重和干重，叶面积，叶绿素含量，光合作用速率和气孔导度均显著降低。应用 Bacillus sp. MN-54 或 P，特别是联合应用，可显著减轻 Pb 对玉米的毒害作用。在较高的 Pb 水平（500 mg kg）下，与对照相比，联合应用可在 45 天和 90 天分别有效降低 42.4％和 50％的 Pb 吸收，43.3％和 46.3％的 Pb 吸收，43.3％和 46.3％的根，以及土壤中有效 Pb 含量的 30.8％和 33.9％。此外，与对照相比，使用 Bacillus sp. MN-54 可使玉米植物对 P 的吸收增加 44.4％。我们的研究结果表明，联合使用 Bacillus sp. MN-54 和 P 可以有效改善 Pb 污染土壤中植物的生长和 Pb 固定化。
