Speaker
Description
Agricultural drainage waters contain recoverable plant nutrients but may contribute to eutrophication when discharged untreated. This study evaluated Lemna minor for nutrient recovery from agricultural drainage water and, more importantly, investigated the unexplored potential of its dried biomass to bind boron (B) in soil and mitigate B toxicity in a crop plant. Duckweed was cultivated in drainage water from a soilless tomato greenhouse and a vertical farm, with nutrient solution as a reference. Nutrient removal and mineral accumulation were determined. The resulting dried biomass was assessed (i) in water, (ii) during a 90-day soil incubation, and (iii) in a cucumber seedling experiment under increasing B supply.
Lemna minor grew successfully in both drainage waters and substantially depleted nitrate and phosphorus while accumulating macro- and micronutrients, including B. Incorporation of dried duckweed into soil at 0.5% (w/w) markedly reduced hot-water-extractable B, and this effect persisted throughout incubation. At soil-relevant pH, the biomass released B into B-free water but bound more than half of the B in B-enriched water, indicating bidirectional buffering capacity. Duckweed amendment increased cucumber shoot biomass across all B levels and prevented visible B-toxicity symptoms at the highest B treatment.
Although the high B-accumulation capacity of living Lemna and the involvement of cell-wall apiogalacturonan are known, this is, to our knowledge, the first demonstration that mineral-rich, dried Lemna biomass retains B-binding functionality in soil and can mitigate B toxicity during crop growth. Thus, agricultural wastewater treatment and nutrient recovery generate a multifunctional soil amendment within a circular agricultural system.
Keywords
boron, cucumber, organic amendment, toxicity
References
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| Scientific Session | Applications |
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