Ameliorative Effects of Trichoderma harzianum and Rhizosphere Soil Microbes on Cadmium Biosorption of Barley (Hordeum vulgare L.) in Cd-Polluted Soil

Cadmium’s presence in agricultural soils resulting from industrial activities, factories, fertilizers, and pesticides is an environmental challenge threatening public health. Therefore, this study was carried out to assess Trichoderma harzianum and indigenous rhizosphere soil microbes’ ability on cadmium absorption, translocation, and tolerance in barley. A pot experiment was conducted in a full factorial randomized design with three replicates. Treatments were T. harzianum (Tri) and rhizosphere soil (Rhi) and Cd at seven levels (0, 1.54, 3.84, 9.6, 24, 60, and 150 mg kg−1). We found that simultaneous application of T. harzianum and indigenous soil microorganisms had positive effects on barley tolerance index (TI), Cd uptake efficiency, shoot dry weight, and plant uptake. Co-inoculation of T. harzianum and soil microorganisms resulted in significantly higher chlorophyll content as compared to plants inoculated only with only T. harzianum or soil microorganisms. The maximum root uptake obtained at 150 mg kg−1 Cd added was in plants also co-inoculated with Tri and Rhi. Also, the Cd uptake efficiency was lower in plants inoculated with Tri and Rhi compared to non-inoculated plants. Meanwhile, Cd uptake efficiency increased with soil Cd up to 133 mg kg−1. The lowest Cd phytoextraction efficiency was observed with Tri and Rhi co-inoculated plants. The obtained results suggest that co-inoculation of T. harzianum and soil microbes ameliorates the negative effects of Cd contamination and could then be used as an option to remediate Cd-contaminated soils even in higher levels than this study.