Evaluation of the tolerance of duckweed (Lemnaceae) to abiotic stress factors associated with nutrient recycling systems via multispectral imaging

• Duckweed species are used in nutrient recycling systems • A multispectral imaging pipeline was developed for stress detection in duckweed • Duckweed clones were assessed for tolerance to NaCl-, NH 4 + -, P-, and K-stress • NH 4 + and NaCl were most detrimental with species and clone specific differences • Lemna minor 7022 is a highly resilient clone to be used in nutrient recycling Lemnaceae , commonly known as the duckweed family, include the smallest flowering plants known to science. Although duckweed holds significant potential for wastewater treatment and nutrient recycling, abiotic stress factors prevailing in nutrient recycling systems can lead to die-off. Given the considerable inter-species and inter-clone morphological and physiological variability, this study aimed to assess the physiological and functional tolerance of 14 duckweed clones belonging to three different species ( Lemna minor, Spirodela polyrhiza , and Wolffia globosa ) to four abiotic stress factors: electrical conductivity (salinity stress), ammonium concentration, phosphorus concentration, and potassium concentration. In all experiments, the physiological and functional tolerance of duckweed was monitored using a multispectral imaging platform, which enabled the assessment of presymptomatic stress responses. The results demonstrated that L. minor clones exhibited greater physiological tolerance to the imposed stress factors, with clone L. minor 7022 emerging as the most tolerant. No health deterioration was observed upon exposure to high concentrations of phosphorus, ammonium, and potassium. This study uniquely demonstrates the use of multispectral imaging as a powerful and non-destructive tool for screening duckweed clones, offering a novel approach to optimize clone selection for its potential application in wastewater treatment and nutrient recovery systems.