Influence of Light Intensity and Spectrum on Duckweed Growth and Proteins in a Small-Scale, Re-Circulating Indoor Vertical Farm

Abstract

Duckweeds can be potentially used in human and animal nutrition, biotechnology or wastewater treatment. To cultivate large quantities of a defined product quality, a standardized production process is needed. A small-scale, re-circulating indoor vertical farm (IVF) with artificial lighting and a nutrient control and dosing system was used for this purpose. The influence of different light intensities (50, 100 and 150 µmol m−2 s−1) and spectral distributions (red/blue ratios: 70/30, 50/50 and 30/70%) on relative growth rate (RGR), crude protein content (CPC), relative protein yield (RPY) and chlorophyll a of the duckweed species Lemna minor and Wolffiella hyalina were investigated. Increasing light intensity increased RGR (by 67% and 76%) and RPY (by 50% and 89%) and decreased chlorophyll a (by 27% and 32%) for L. minor and W. hyalina, respectively. The spectral distributions had no significant impact on any investigated parameter. Wolffiella hyalina achieved higher values in all investigated parameters compared to L. minor. This investigation proved the successful cultivation of duckweed in a small-scale, re-circulating IVF with artificial lighting.

Modelling of Lemna minor L. growth as influenced by nutrient supply, supplemental light, CO2 and harvest intervals for a continuous indoor cultivation

“…It is supported by the observation over three years of experiments that each variety results in a different capacity W max of the population under the same experimental conditions (light quality and quantity, nutrients, temperature, CO 2 ). For that reason, in the literature, the growth rates are in general indicated for a specific species, ( Khvatkov et al., 2018 ; asfar et al., 2007; Petersen et al., 2021 ; Petersen et al., 2022 ; van Dyck et al., 2022 ). As can be seen below, W max has to be inserted into the model as one of the most important parameters.…”

“…ii) optimum supplemental light in quantity and quality ( Petersen et al., 2022 ; Stewart et al., 2020 )…”

“…As a source for novel food and further substances ( Schmidt 2020 , 2021 ; Schmidt et al., 2018 ). To this end, growth parameters have to be optimized to provide a continuous uninhibited growth and constant quality ( Petersen et al., 2022 ) Given the numerous possible combinations of e.g. temperature, nutrient concentrations and ratios, light, CO 2 levels and harvest schedules, a model approach had to be developed where the best combination of many factors can be assessed.…”

“…Considering the dynamics of NO 3 - and NH 4 + uptake in duckweed ( Zhou et al., 2021 ), a NH 4 + /NO 3 - ratio of 25/75, as used by Petersen et al. (2021 , 2022) , cannot be confirmed as appropriate under conditions of long term cultivation. According to light adaption, circadian clock effects have to be considered ( Ueno et al., 2021 ) by taking care of 16/8 (light/dark) photoperiods in all experiments at all locations.…”

Species- and Metal-Specific Responses of the Ionome of Three Duckweed Species under Chromate and Nickel Treatments

“…The produced duckweed biomass has a favorable composition with e.g., high protein, starch and fiber content [ 6 ]. These traits make duckweeds potent candidate crops for use as biofuel, feed, or food in circular economic approaches [ 4 , 7 ]. In addition, duckweeds are also known to efficiently incorporate many trace elements, and this can potentially make these plants suitable for the remediation of industrial effluents.…”