With the increasing adoption of hydroponic cultivation system, the demand for clean and safe irrigation water has grown significantly. Therefore, sustainable and environmentally friendly water treatment methods are needed to ensure microbial safety. This study investigated the effects of an eco-friendly REDOX water treatment system employing a Cu-Zn alloy fiber to sterilize water via redox reactions on the growth and antioxidant capacity of lettuce (Lactuca sativa) and kale (Brassica oleracea). Seedlings were cultivated under controlled conditions and irrigated for 28 days with either a standard nutrient solution (control) or a nutrient solution prepared using REDOX-treated water (treatment). Growth parameters were monitored, and samples were collected at 7-day intervals for biochemical analysis. While no significant differences were observed in plant growth over the 28-day cultivation period, changes in total phenol and flavonoid contents, as well as antioxidant activity were observed over time with differing trends between the control and treatment groups depending on the sampling date. For example, in lettuce at 7 days after transplanting (DAT), the treatment group showed higher phenol content and FRAP activity (105.66 ± 0.62 mg GAE g− 1 DW and 3,761.47 ± 34.30 µmol TE g− 1 DW, respectively) compared to the control group (100.78 ± 0.42 mg GAE g− 1 DW and 3,264.00 ± 37.76 µmol TE g− 1 DW, respectively). However, at 21 DAT, the control group exhibited higher phenol content and FRAP activity than the treatment group. Water quality analysis revealed differences in Fe and Zn concentrations in the nutrient solution, and these differences appeared to be reflected in the elemental composition of plant tissues, suggesting a potential relationship between water composition and nutrient uptake. Additionally, the treatment significantly reduced total bacterial and Escherichia coli colony counts over time, confirming the sanitizing effect of the REDOX water treatment system. In conclusion, the REDOX water treatment system, which utilizes a Cu-Zn alloy fiber to induce redox reactions, did not significantly influence the overall growth of lettuce and kale during the 28-day cultivation period. However, it enhanced the antioxidant profile of both crops by increasing total phenol and flavonoid contents, as well as ABTS and FRAP activities. These changes were accompanied by elevated Zn and reduced Fe concentrations in plant tissues, reflecting the altered nutrient composition of treated water. In addition, the system effectively reduced microbial contamination, including total bacterial and E. coli colony counts, suggesting its potential utility in improving water safety. Overall, REDOX-treated water may serve as a sustainable alternative for safe water reuse in hydroponic cultivation without compromising crop quality.

Effects of eco-friendly REDOX water treatment on growth and antioxidant activity in lettuce and kale

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发表日期：

2025年10月15日

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Min Hyeok Baek,
In Seon Kim,
Jung Su Jo

摘要

With the increasing adoption of hydroponic cultivation system, the demand for clean and safe irrigation water has grown significantly. Therefore, sustainable and environmentally friendly water treatment methods are needed to ensure microbial safety. This study investigated the effects of an eco-friendly REDOX water treatment system employing a Cu-Zn alloy fiber to sterilize water via redox reactions on the growth and antioxidant capacity of lettuce (Lactuca sativa) and kale (Brassica oleracea). Seedlings were cultivated under controlled conditions and irrigated for 28 days with either a standard nutrient solution (control) or a nutrient solution prepared using REDOX-treated water (treatment). Growth parameters were monitored, and samples were collected at 7-day intervals for biochemical analysis. While no significant differences were observed in plant growth over the 28-day cultivation period, changes in total phenol and flavonoid contents, as well as antioxidant activity were observed over time with differing trends between the control and treatment groups depending on the sampling date. For example, in lettuce at 7 days after transplanting (DAT), the treatment group showed higher phenol content and FRAP activity (105.66 ± 0.62 mg GAE g^− 1 DW and 3,761.47 ± 34.30 µmol TE g^− 1 DW, respectively) compared to the control group (100.78 ± 0.42 mg GAE g^− 1 DW and 3,264.00 ± 37.76 µmol TE g^− 1 DW, respectively). However, at 21 DAT, the control group exhibited higher phenol content and FRAP activity than the treatment group. Water quality analysis revealed differences in Fe and Zn concentrations in the nutrient solution, and these differences appeared to be reflected in the elemental composition of plant tissues, suggesting a potential relationship between water composition and nutrient uptake. Additionally, the treatment significantly reduced total bacterial and Escherichia coli colony counts over time, confirming the sanitizing effect of the REDOX water treatment system. In conclusion, the REDOX water treatment system, which utilizes a Cu-Zn alloy fiber to induce redox reactions, did not significantly influence the overall growth of lettuce and kale during the 28-day cultivation period. However, it enhanced the antioxidant profile of both crops by increasing total phenol and flavonoid contents, as well as ABTS and FRAP activities. These changes were accompanied by elevated Zn and reduced Fe concentrations in plant tissues, reflecting the altered nutrient composition of treated water. In addition, the system effectively reduced microbial contamination, including total bacterial and E. coli colony counts, suggesting its potential utility in improving water safety. Overall, REDOX-treated water may serve as a sustainable alternative for safe water reuse in hydroponic cultivation without compromising crop quality.