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Enhancing Native Plant Establishment in Mine Tailings under Drought Stress Conditions through the Application of Organo-Mineral Amendments and Microbial Inoculants
Atika, M.; Leila, B.; Pereira, S.I.A.; Castro, P.M.L.; Ali, B. Enhancing Native Plant Establishment in Mine Tailings under Drought Stress Conditions through the Application of Organo-Mineral Amendments and Microbial Inoculants. Plants2024, 13, 863.
Atika, M.; Leila, B.; Pereira, S.I.A.; Castro, P.M.L.; Ali, B. Enhancing Native Plant Establishment in Mine Tailings under Drought Stress Conditions through the Application of Organo-Mineral Amendments and Microbial Inoculants. Plants 2024, 13, 863.
Atika, M.; Leila, B.; Pereira, S.I.A.; Castro, P.M.L.; Ali, B. Enhancing Native Plant Establishment in Mine Tailings under Drought Stress Conditions through the Application of Organo-Mineral Amendments and Microbial Inoculants. Plants2024, 13, 863.
Atika, M.; Leila, B.; Pereira, S.I.A.; Castro, P.M.L.; Ali, B. Enhancing Native Plant Establishment in Mine Tailings under Drought Stress Conditions through the Application of Organo-Mineral Amendments and Microbial Inoculants. Plants 2024, 13, 863.
Abstract
The implementation of phytoremediation strategies under arid and semi-arid climate requires the use of appropriate plant species capable of withstanding multiple abiotic stresses. In this study, we assessed the combined effects of organo-mineral amendments and microbial inoculants on chemical and biological properties of mine tailings, as well as on growth of native plant species under drought stress conditions. Plants were cultivated in pots containing 1 kg of a mixture of mine tailings and topsoil (i.e. pre-mined superficial soil) in a 60:40 ratio, 6% marble sludge and 10% sheep manure. Moreover, a consortium of four drought-resistant rhizobacteria was inoculated. Three irrigation levels were applied: well-watered, moderate water deficit, and severe water deficit, corresponding to 80%, 45%, and 30% of field capacity, respectively.
The addition of topsoil and organo-mineral amendments to mine tailings significantly improved their chemical and biological properties, which were further enhanced by bacterial inoculation and plants’ establishment. Water stress negatively impacted enzymatic activities in amended tailings, resulting in a significant decrease of acid and alkaline phosphatases, urease, and dehydrogenase activities. Similar results were obtained for bacteria, fungi and actinomycetes abundance. PGPR inoculation positively influenced the availability of phosphorus, total nitrogen, and organic carbon, while increased alkaline phosphatase, urease (by about 10%) and dehydrogenase activities (by 50%). The rhizosphere of P. harmala showed the highest enzymatic activity and number of culturable microorganisms, especially in inoculated treatments. Severe water deficit has nega-tively affected plant growth, leading to a 40% reduction in shoot biomass of both Atriplex halimus and Pennisetum setaceum compared to well-watered plants. Peganum harmala showed greater tolerance to water stress, as corroborated by the lower decreases observed in root and shoot length and dry weight compared to well-watered plants. The use of bioinoculants mitigated the negative effects of drought on P. harmala shoot biomass, resulting in an increase of up to 75% in the aerial biomass in plants exposed to severe water deficit.
In conclusion, the results suggest that the combination of organo-mineral amendments, PGPR inoculation and P. harmala represents a promising approach to enhance the phytoremediation of metal-polluted soils under semi-arid conditions.
Environmental and Earth Sciences, Environmental Science
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