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ISSN : 1226-9999(Print)
ISSN : 2287-7851(Online)
Korean J. Environ. Biol. Vol.43 No.2 pp.186-195
DOI : https://doi.org/10.11626/KJEB.2025.43.2.186

Optimization of indoor vertical farming system for cultivating Spirodela polyrhiza L., a Korean duckweed

Tae Yook Huh1,2, Yongha You3, Jun Seong Park2, Jeong Hyun Kim2, Yujin Son2, Gahyun Kim2, Kwang-Soo Jung1,2, Sung-Eun Lee1,3*
1Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
2Research Station, Viroute Inc., Daegu 41260, Republic of Korea
3Department of Integrative Biology, Kyungpook National University, Daegu 41566, Republic of Korea
*Corresponding author Sung-Eun Lee Tel. 053-950-7768 E-mail. selpest@knu.ac.kr

†These authors contributed equally to this work.


Contribution to Environmental Biology


▪ This study provides an effective cultivation strategy to increase biomass production of Spirodela polyrhiza using an indoor vertical farming system.


▪ Protein contents were significantly increased in indoor cultivated S. polyrhiza, whereas Pb, Cd, and As concentrations were remarkably reduced in the same sample.


31/05/2025 16/06/2025 24/06/2025

Abstract


Spirodela polyrhiza (L.) has been known as greater duckweed or great duckmeat. It is native inhabited in Korea. It is considered as a rich source of primary metabolites including protein, carbohydrates, and fats. Thus, it is considered as an alternative food source for the future. In addition, it has a strong phytoremediation capacity to remove various environmental pollutants, especially inorganic elements and pesticides. With a variety of duckweed’s application, there is an urgent need to develop a cultivation method for a sustainable supply of S. polyrhiza. In this study, an indoor vertical farm has been introduced to optimize duckweed cultivation. Indoor cultivated S. polyrhiza showed about 2-fold higher fresh weight than outdoor cultivated duckweed. Contents of inorganic elements were also significantly reduced in indoor cultivated S. polyrhiza. Especially, lead (Pb), cadmium (Cd), and arsenic (As) were approximately 10-fold decreased in indoor cultivated duckweed. On the other hand, contents of proteins and fats were significantly increased in indoor cultivated S. polyrhiza, while carbohydrates were found more in outdoor cultivated S. polyrhiza. Increasing N content in a homemade nutrition solution also enhanced fresh and dried weights of S. polyrhiza by about 1.8-fold in comparison with other commercial nutrition solutions. Proliferation rate (%) was doubled every 24 hours in this indoor vertical farm, indicating the accomplishment of a sustainable supply for S. polyrhiza. Further studies need to be undertaken to cultivate other duckweeds such as Wolffia arrhiza and Lemna minor using the same indoor farming system.


indoor vertical farm , duckweeds , Spirodela polyrhiza , proteins , sustainable supply

초록

    1. INTRODUCTION

    Climate change has dramatically altered ecosystems, which in turn has had a major impact on agriculture, which produces food raw materials. Much of the literature suggests that climate change will have a major impact on food security in the future (Gregory et al. 2005;Brown and Funk 2008;Smith and Gregory 2013;Wheeler and Von Braun 2013). The growing societal interest in sustainable food, not only due to climate change, but also due to events such as the Covid-19 pandemic, has accelerated the development of advanced technologies to supply sustainable foods to consumers (Galanakis 2024;Mešić et al. 2024). For example, molecular agriculture, which covers both cell culture and agricultural production, is developing, and food system technologies (FSTs) have recently been introduced for sustainable food, which leads to higher willingness to pay (WTP), one of the social psychological phenomena. FSTs can be divided into four parts: plantbased alternatives (PBAs), vertical farming (VF), food deliveries (FD), and blockchain technology (BT) (Bunge et al. 2022).

    Duckweed has been studied as a plant-based alternative food or livestock feed (Yahaya et al. 2022;Sosa et al. 2024). Protein is an essential ingredient for humans, and plant-based protein alternatives are primarily soy protein. Soybeans have shown a scenario of declining yields as global warming accelerates (Rose et al. 2016), and the cultivation of soybeans produces large amounts of greenhouse gases, which accelerate global warming (Castanheira and Freire 2013). Duckweed has been proposed as an alternative to soy protein as the main utilized vegetable protein source. The protein content of duckweed is about 40 grams per 100 grams of building, which indicates that it can be used as a substitute compared to soybeans, which have about 30-50% protein (Xu et al. 2023). Furthermore, compared to animal proteins, plant proteins are composed of less essential amino acids for humans. In addition, soy protein contains one of the top eight food allergens listed by the Food and Agriculture Organization (FAO). However, when the protein from duckweed was concentrated, it was found to be 92% Rubisco protein (Nieuwland et al. 2021).

    Rubisco protein provides all essential amino acids and is a highly digestible, non-allergenic protein (Nawaz et al. 2024). In the case of duckweed cultivation, the production of greenhouse gases (GHGs) from soybean cultivation has been found to be avoided and even reduced (Rabaey and Cotner 2022). Duckweed has further been shown to mitigate eutrophication of habitats by rapidly absorbing nutrients from the habitat in addition to GHGs (Sims et al. 2013). Duckweed also grows very quickly, suggesting it is an alternative food source. Under optimal conditions, duckweed doubles in about 16-48 hours, which translates to about 50 days for a 10 cm2 cover to become 1 ha. This is followed by another 10 days for a total of 60 days to reach 32 ha (Leng 1999;Goopy et al. 2004).

    Duckweed is a floating aquatic plant that grows on the surface of water, making it a good candidate for vertical farming. However, producing it in large quantities needs a facility that can provide standardized environmental conditions. Indoor vertical farms (IVF) can control light, temperature, and humidity to create optimal environmental conditions according to this purpose. Different light levels have been shown to increase growth rate (67-76%) and protein content (50-89%) (Petersen et al. 2022). This suggests that duckweed is a suitable crop for the application of technologies such as PBAs, IVF, and FSTs.

    Herein, we optimized the mass cultivation of Spirodela polyrhiza (L.) in indoor vertical farm, and experiments were designed in consideration of two fronts. First, as a cultivation environment factor, S. polyrhiza were grown in an indoor hydroponic system (25±1°C, 16 h photoperiod) using homemade nutritional solution. Growth rate, biomass, and major nutritional components of indoor grown S. polyrhiza were compared to S. polyrhiza populations collected from Samjeongji (Gyeongsan-si, Gyeongbuk-do, Korea) cultivated under Samjeongji raw water for 7 days. Second, growth responses (leaf area, root length, fresh and dried weight) and heavy metal accumulation content were also evaluated by applying international standard Yamazaki nutritional solution, commercially available Mulpure nutritional solution, and homemade nutritional solution, which enhanced nitrogen-calcium content as cultivating nutrition composition factors.

    2. MATERIALS AND METHODS

    2.1. Chemicals

    Methanol and sodium borohydride were purchased from Daejung Chemical & Metals Co., Ltd. (Siheung, Korea). Sodium chloride was purchased from Duksan Pure Chemical Co., Ltd. (Ansan, Korea). Potassium nitrate, calcium nitrate tetrahydrate, magnesium sulfate heptahydrate, and ammonium dihydrogen phosphate were purchased from Daemyung Chemical Co., Ltd. (Hwaseong, Korea). Deionized water (D.I. water) was prepared using an ultrapure water preparation device (Human Power I+; Human Science, Hanam, Korea), and all reagents were used without further purification.

    2.2. Collection of Spirodela polyrhiza L.

    To obtain duckweed plant material for the study, Spirodela polyrhiza L. was collected from Samjeongji, located at 577, Seojeong-ri, Jain-myeon, Abyang-eup, Gyongsan-si, Gyeongsangbuk-do, Republic of Korea. S. polyrhiza populations were collected on September 1, 2023. The outdoor conditions were observed as the average air temperature was about 25°C and the water temperature in the field averaged about 24°C in the middle of the day (12:00-14:00 pm), and the daily sunshine time of photoperiod was about 8 hours.

    To ensure the proper purity for DNA amplification of wild-collected plant sample, S. polyrhiza L. was dried at 50°C for 14 h, and then a fine powder with an average particle size of 700 nm (±100 nm) was obtained using a nanomill (XQM-12A; TENCAN, Changsha, China). The absorbance spectrum ranges of the spectrophotometer (Hitachi U-5100; Hitachi, Tokyo, Japan) used for the absorbance measurement of the prepared S. polyrhiza powder in TE buffer (pH 8.0) was set from 200 nm to 400 nm, and the purity of the nucleic acid was measured after dilution using TE buffer (pH 8.0) to determine the A260/A230 and A260/A280 values. The A260/A230 value was measured to be 2.0456 and the A260/A280 value was measured to be 1.9044, confirming that it could be used with suitable purity for DNA amplification. The genetic information of S. polyrhiza was confirmed by RT-qPCR analysis (T-100; Bio-rad, Hercules, USA) by measuring the absorbance of the collected samples, and 100 individuals replicated by nutrient propagation indoors for more than 10 times were used as research materials in triplicate.

    2.3. Environmental conditions for S. polyrhiza growth in indoor vertical farming

    Growing conditions were set to a 16-hour light cycle and 8-hour darkness. The pH of the hydroponic nutrient solution for the duckweed study was maintained between 6.5 and 7.0, and the nutrient concentration was set at 800 ppm. The water temperature was maintained at 25±1°C, the room temperature was set at 25-28°C, and the humidity was 80%. The duckweed nutrient solutions used in the test were Yamazaki plant nutrition solution for triple leaf (Seo et al. 2009), Moolpurae series 1-Ho (Daeyu, Seoul, Korea), and homemade hydroponic nutrient solution. The nutritional composition of Yamazaki plant nutrition solution and homemade hydroponic nutrient solution is listed in Table 1. Homemade nutrition solution increased N contents for duckweed growth when compared to Yamazaki plant nutrition solution.

    The experiments were conducted with two different cultivation conditions with cultivating sites (indoor and outdoor) and nutritional differences (Yamazaki nutritional solution, commercially available Mulpure nutritional solution, and Homemade nutritional solution).

    Each treatment combination was incubated for 7 days in replicates (n=10) with equalized initial inputs (30± 2 mg fresh weight per bed). Dependent variables were measured with leaf area (mm2 plant-1), root length (mm plant-1), fresh and dried weights (g plant-1), and accumulation of heavy metals (Cu, Pb, Cd, As, Ni) using day 7 samples.

    2.4. Indoor vertical farming (IVF) of S. polyrhiza

    Selected duckweed specimens were transplanted into an indoor hydroponic system and assessed for proliferation 24 hours later. Indoor farming systems were set up as two cultivation beds were managed. The used culture bed was sized as 400 cm×120 cm×10 cm (length× width×height), filled with water to 8 cm. The light source was set to 89 μmol of red and 38 μmol of blue to grow duckweed. The nutrient solution was diluted 100 times the amount of water, and the EC value was maintained at 750±50 ppm. The water was maintained by replacing the entire water volume once a week and checking the evaporated level once a week and adding water accordingly. We did not inject antibiotics for microbial infections.

    The proliferating duckweed individuals were manually counted and measured, and if multiple individuals were connected by petioles, they were counted separately. Duckweed proliferation rates were calculated using the Braun-Blanquet method as below (Van Der Maarel 1975).

    Proliferation rate (%) = [(number of individuals at termination-number of initial transplants)/number of initial transplants]×100

    2.5. Analytical procedures

    Metal ions were analyzed following microwaveassisted acid digestion of the samples, and the concentrations of lead, cadmium, arsenic, and copper were subsequently determined using inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). In addition, the nutritional components were analyzed in accordance with the Korean Food Standards Codex (Ministry of Food and Drug Safety, Korea): protein content was determined using the Kjeldahl method, fat content was measured by the crude fat extraction method, and vitamin content was quantified by high-performance liquid chromatography equipped with a photodiode array detector (HPLC-PDA). All other components were analyzed following the official methods specified in the Korean Food Standards Codex.

    2.6. Statistical analysis

    Experiments were performed in triplicate, and results were expressed as mean value±standard deviation (SD). A t-test was performed to evaluate differences in growth responses and heavy metal accumulation in S. polyrhiza according to their cultivation conditions as indoor and outdoor. On the other hand, t-test was used to compare the nutritional composition of duckweeds cultivated in water and homemade nutritional solutions. One-way ANOVA with Tukey’s post hoc test was used to analyze five-day growth with different nutrient solutions, and population size of S. polyrhiza under indoor hydroponic conditions. Statistical analysis was performed using IBM SPSS Statistics (version 26.0, Armonk, USA) software.

    3. RESULTS AND DISCUSSION

    3.1. Changes in the growth and composition of S. polyrhiza according to the environment

    An indoor cultivation system for growing S. polyrhiza was undertaken and its growth parameters such as leaf area, root length, fresh weight, and dry weight were compared with those of outdoor grown S. polyrhiza. Indoor grown S. polyrhiza showed 3.23 mm2 of leaf area, 38.0 mm of root length, 0.16 g of fresh weight, and 0.008 g of dried weight, while outdoor grown S. polyrhiza exhibited 1.56 mm2 of leaf area, 21.6 mm of root length, 0.078 g of fresh weight, and 0.0034 g of dried weight (Table 2). After harvest, differences in S. polyrhiza appearance were found as shown in Figure 1. Indoor cultivation environment was set up as the water temperature was 25°C, the air temperature was 28°C on average, and the light was 16 hours light mode and 8 hours dark mode. However, outdoor cultivation environment was not controlled properly the temperature and light strength in comparison to indoor cultivation system. Therefore, the controlled indoor cultivation allowed maximizing S. polyrhiza yields and doubling time, whereas outdoor cultivation system supplied less energy with natural sunlight towards S. polyrhiza.

    These findings are similar to those of Coughlan et al. (2022). As Coughlan et al. (2022) demonstrated that duckweeds represented a suitable plant for indoor farming, they constructed a stacked system consisting of 15 m2 of duckweed per m2 of floor space. With this system, they maximized yields with doubling time of 1.24 days. In our work, indoor cultivated S. polyrhiza yielded about 2-fold higher than outdoor cultivated S. polyrhiza in terms of fresh weight, and about 2.1-fold higher for dried weight basis. S. polyrhiza is suitable for indoor cultivation system.

    The average concentrations of heavy metal such as cadmium, copper, lead, and arsenic were determined in the outdoor grown S. polyrhiza and indoor cultivated S. polyrhiza (Table 3). The average content of lead (Pb) was found to be 2.11 mg kg-1 in the outdoor grown S. polyrhiza, while the indoor cultivated S. polyrhiza contained 0.15 mg kg-1. It was significantly different (14- fold difference) between two plant samples, indicating that indoor water system was free from inorganic elements including metal ions in the Earth’s crust. Other two metal ions like cadmium and arsenic showed similar pattern of presence when compared to lead. The average content of cadmium (Cd) was found to be 0.12 mg kg-1 in the outdoor grown S. polyrhiza and 0.01 mg kg-1 in the indoor cultivated S. polyrhiza. The content of arsenic (As) was 1.42 mg kg-1 in outdoor grown S. polyrhiza and 0.16 mg kg-1 in the indoor cultivated S. polyrhiza (Table 3). These three metal ions were significantly decreased in the indoor cultivated S. polyrhiza when compared to outdoor grown S. polyrhiza. However, the content of copper (Cu) was 10.55 mg kg-1 in the outdoor grown S. polyrhiza and 7.17 mg kg-1 in the indoor cultivated one, which was close to each other.

    Many studies showed that S. polyrhiza can absorb or accumulate meta ions from growth medium. Manganese (Mn) and chromium (Cr) can be removed by S. polyrhiza with the tolerance of 70 mg L-1 and 12 mg L-1 for Mn and Cr, respectively (Liu et al. 2017). The duckweed was treated with the single or dual metals of Mn and Cr with range of 5-70 mg L-1 for Mn and 2-12 mg L-1 for Cr (VI) under the laboratory conditions, and Mn in the plant biomass was accumulated up to 15.75 mg per g of dried duckweed and 2.85 mg for Cr (Liu et al. 2017). Similarly, S. polyrhiza absorbed metal ions like copper (Cu) and nickel (Ni) as well as Mn and Cr (Pandey et al. 1999). Other duckweed plants have excellent removal capacities for metal ions. For example, Lemna gibba removed Cr, Cu, Pb, and Zn from industrial wastewater pond (Hegazy et al. 2009). With our results, S. polyrhiza can remove metal ions in the outdoor environment, but it can absorb metal ions in indoor environments because of less supply of metal ions when compared to outdoor environment.

    The nutritional analysis of S. polyrhiza grown in different cultivation conditions showed that the carbohydrate, crude protein, and crude fat contents were 52.78%, 21.90%, and 2.50%, respectively, in the outdoor grown S. polyrhiza, and 41.41%, 33.81%, and 5.22%, respectively, in the indoor cultivated S. polyrhiza (Appendix Table A1). With this result, crude protein content was increased with the controlled cultivation system, thus indoor cultivation system may be fit to protein production using duckweed.

    The vitamin composition analysis showed that the content of vitamins A, B1, B2, B3, B6, B9, B12, and E in the indoor cultivated S. polyrhiza was higher than that of the wild species (Appendix Table A1). In particular, vitamins A and B3 were measured to be 0.172% and 0.0261%, respectively, in the indoor cultivation, which was more than twice that of the outdoor grown S. polyrhiza, confirming that the indoor cultivation may supply higher nutritional value than the outdoor cultivation system for S. polyrhiza (Xu et al. 2023).

    3.2. Changes in S. polyrhiza growth according to nutrient solution and indoor growing system

    The growth of indoor-cultivated S. polyrhiza was examined in response to changes of N content in different nutrient solutions, and N content showed significantly different growth of S. polyrhiza between treatments. Among various Yamazaki nutrient solutions available for aquatic Apiaceae family cultivation, Yamazaki nutrient solution for trifoliate exhibited leaf area of 3.23 mm2, root length of 37.93 mm, fresh weight of 0.159 g, and dried weight of 0.0079 g. These results indicate that Yamazaki nutrition solution was effective to grow S. polyrhiza in the indoor vertical farms with the increased production of 143% and 158% in terms of fresh weight and dried weight, respectively, when compared to the control plant (Table 4). Another plant growth nutrition solution, Mulpure (Daeyu Co. Ltd.), exhibited very similar results of Yamazaki nutrition solution due to possible compositional similarity.

    On the other hand, the nutrient solution (homemade nutrition solution) prepared in this study by increasing the N content of the previous Yamazaki solution (Table 1) showed the highest cultivation products (Table 4) when compared to the other two nutrition solutions and the control group. The control group was grown hydroponically indoors at 25°C under a 16/8 h light/dark cycle, with only tap water supplied. S. polyrhiza grown in the homemade nutrition solution possessed leaf area of 5.90 mm2, root length of 43.0 mm, fresh weight of 0.257 g, and dried weight of 0.0129 g. These results showed a significant increase of 230% and 258% in terms of fresh weight and dried weight, respectively, when compared to the control S. polyrhiza. It is very close to those results published by Said et al. (2022), and they reported that the difference in N content in the nutrition solution for S. polyrhiza affected the growth rate.

    As S. polyrhiza growth was significantly increased in the homemade nutritional solution, nutritional parameters in S. polyrhiza grown in the homemade nutrition solution were compared to the control plants. Carbohydrate content in the S. polyrhiza grown in the homemade nutrition solution was 42 mg 100 g-1, crude protein was 29.04%, and crude fat was 1.47%. In addition, calcium was measured to be 2,375.10 mg 100 g-1 and potassium was 3,411.49 mg 100 g-1 (Table 5). Crude protein, calcium and potassium contents were significantly improved in the S. polyrhiza grown in the homemade nutrition when compared to the control group (Table 5).

    In the proliferation rate experiment of S. polyrhiza in our indoor hydroponic automated cultivation system, the population was increased doubly within 24 hours and it enhanced again doubly at 48 hours (Fig. 2). However, the variation was found between 24 and 48 hours, indicating that the controlled system might be inefficiently after 48 hours. It was quite similar to the previous results on the duckweed growth rate (%) (Yu et al. 2014).

    4. CONCLUSIONS

    Duckweeds are a plant rich in protein, carbohydrates, and fats, making them a promising protein substitute for meat. Other trace elements are abundantly present, and especially S. polyrhiza produces apiogalacturonan, a pectin that utilizes the pentose sugar apiose. Duckweed also plays a special role in removing various environmental pollutants from the aquatic environment. It has the ability to eliminate uranium, including various inorganic elements, and it also abolishes organic pollutants that threaten aquatic ecosystems such as pesticides. Through our research, we suggested the cultivation method using the indoor vertical farm system of S. polyrhiza and developed a homemade nutrition solution with increased N in Yamazaki nutrition solution to optimize the duckweed growth. With this cultivation method, the content of protein in our cultivation system was increased, while the content of inorganic elements was decreased. The optimized indoor verticalfarm accomplished proliferation rates with doubly population of S. polyrhiza within 24 hours. Therefore, indoor vertical farm in this study was successfully introduced to cultivate S. polyrhiza to produce sustainable protein supply.

    ACKNOWLEDGMENTS

    This work was supported by the 2023 Startup Growth Tech Incubator Program for Startups (TIPS), funded by the Ministry of SMEs and Startups (MSS), Korea, and administered by the Korea Technology and Information Promotion Agency for SMEs (TIPA) (Project No. RS-2023-00285305).

    CRediT authorship contribution statement

    TY Huh: Conceptualization, Investigation, Methodology, Visualization, Writing-Original draft. Y You: Investigation, Methodology, Writing-Original draft. JS Park: Investigation, Methodology, Visualization. JH Kim: Investigation, Methodology, Visualization. Y Son: Investigation, Methodology, Visualization. G Kim: Investigation, Methodology, Visualization. KS Jung: Investigation, Methodology, Visualization. SE Lee: Conceptualization, Investigation, Methodology, Writing- Original draft, Writing-Review & editing.

    Declaration of Competing Interest

    The authors declare no conflicts of interest.

    Figure

    KJEB-43-2-186_F1.gif

    Morphological differences in Spirodela polyrhiza L. under different growth environments, including the wild (A) and an indoor environment under controlled conditions (B). S. polyrhiza L. samples collected from the wild (C) and those cultivated indoors under controlled conditions (D) are shown.

    KJEB-43-2-186_F2.gif

    The population size of Spirodela polyrhiza L. cultivated in an indoor automated hydroponic system under controlled environmental conditions. The experiment was initiated with 200 individuals grown using a homemade nutritional solution at 0 hours. Population size was measured at 24 and 48 hours. Statistical analysis was performed using one-way ANOVA, followed by post hoc Tukey’s test. Different lowercase letters denote significant differences among groups: a>b (p-value<0.001).

    Table

    Nutritional compositions of the Yamazaki plant nutrition solution and homemade hydroponic nutrient solution used for Spirodela polyrhiza L. growth

    * indicates that the manufacturer did not display the composition of Mulpurae nutritional solution.

    Comparisons of leaf area, root length, fresh weight, and dry weight of Spirodela polyrhiza L. grown under outdoor and indoor conditions

    All measurements were taken as follows: leaf area (mm2), root length (mm), fresh weight (g), and dry weight (g). Data are presented as mean±standard deviation. Statistical analysis was performed using a t-test, and statistical significance was indicated by asterisks (***; p<0.001).

    Comparisons of lead, cadmium, arsenic, and copper contents in Spirodela polyrhiza L

    Data are presented as mean±standard deviation. Statistical analysis was performed using a t -test, and statistical significance was indicated by asterisks (**; p<0.01, ***; p<0.001)

    Assessment of five-day growth of Spirodela polyrhiza L. in response to changes in nutrient solution

    All measurements were taken as follows: leaf area (mm2), root length (mm), fresh weight (g), and dry weight (g). Data are presented as mean±standard deviation. Statistical analysis was performed using one-way ANOVA, followed by post hoc Tukey’s test. Lowercase letters denote significant differences among groups: a>b>c>d (p-value<0.05). The control group was grown hydroponically indoors at 25°C under a 16/8 h light/dark cycle, with only tap water supplied. The Yamazaki plant, homemade, and Mulpure nutrient solution groups were also grown hydroponically under the same conditions, each supplied with its respective nutrient solution. Mulpure (Dae Yoo Co., Ltd., Seoul, Korea) is a commercial hydroponic nutrient solution.

    Comparisons of nutritional components of Spirodela polyrhiza L. cultivated in water and homemade hydroponic nutrient solution optimized for duckweed

    All measurements were taken as follows: carbohydrates (mg 100 g-1), crude protein (%), crude fat (%), calcium (mg 100 g-1), and potassium (mg 100 g-1). Data are presented as mean±standard deviation. Statistical analysis was performed using a t -test, and statistical significance was indicated by asterisks (**; p<0.01, ***; p<0.001). The control group was grown hydroponically indoors at 25°C under a 16/8 h light/dark cycle, with only tap water supplied. The homemade nutrient solution group was also grown hydroponically under the same conditions, supplied with a nutrient solution formulated with increased nitrogen content.

    Nutritional components per 100 g dry weight of Spirodela polyrhiza L

    *Based on 100 g of dried Spirodela polyrhiza L.

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    Vol. 40 No. 4 (2022.12)

    Journal Abbreviation 'Korean J. Environ. Biol.'
    Frequency quarterly
    Doi Prefix 10.11626/KJEB.
    Year of Launching 1983
    Publisher Korean Society of Environmental Biology
    Indexed/Tracked/Covered By

    Contact info

    Any inquiries concerning Journal (all manuscripts, reviews, and notes) should be addressed to the managing editor of the Korean Society of Environmental Biology. Yongeun Kim,
    Korea University, Seoul 02841, Korea.
    E-mail: kyezzz@korea.ac.kr /
    Tel: +82-2-3290-3496 / +82-10-9516-1611