Minimizing Heavy Metal Accumulation in Edible Parts of Lettuce Plant

T HE experiment was conducted to reduce the buildup of heavy metals in lettuce plants grown in contaminated soil. Lettuce plants cv. Nader were cultivated on polluted soil in black polyethylene bags with or without the addition of biochar, rice straw, Pseudomonas fluorescens bacterial inoculation, biochar + rice straw, biochar + P. fluorescens , rice straw + P. fluorescens , and biochar + rice straw + P. fluorescens , as well as unpolluted soil as a control. The experiments were conducted in the seasons of 2019 and 2020 at the Vegetable Farm of the Faculty of Agriculture, Ain Shams University, Shubra El Kheima, Qalyubia Governorate, Egypt. The experimental treatments were distributed in a completely randomized design with three replicates. The attained results indicated that cultivating lettuce in polluted soil had negative effects on plant growth compared to those cultivated in unpolluted soil. Application of the experimental treatments improved the vegetative growth parameters, including plant length, leaf area, fresh and dry head weight, fresh and dry root weight, and head diameter. The results also showed that lettuce plants grown in heavy metal-polluted soil had lower values of vegetative growth parameters than those grown in polluted soil treated with biochar, rice straw, or P. fluorescens , and the interaction between them. When compared to bacterial inoculation treatment, the application of biochar and/or rice straw on lettuce plants grown in heavy metal-contaminated soil enhanced growth and leaf nutrient contents, while heavy metal contents decreased. The findings demonstrated that heavy metal-contaminated soil treated with biochar alone or in combination with rice straw and/or bacterial inoculation were effective in reducing the content of heavy metals in plant leaves and attenuating the harmful effects of heavy metals on grown lettuce plants