Effects of pre-harvest brackish water exposure on leafy green growth in aquaponic systems

Authors: DUSCI, JOSHUA - Virginia State University; BELL, NATASHA - Virginia Polytechnic Institution & State University; FENG, YIMING - Virginia Polytechnic Institution & State University; Romano, Nicholas; CHILDRESS, CURTIS - Virginia Polytechnic Institution & State University; ABEYRATHNE, BUDDHIKA - Virginia Polytechnic Institution & State University

Submitted to: Frontiers in Sustainable Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2026
Publication Date: 6/10/2026
Citation: Dusci, J., Bell, N.L., Feng, Y., Romano, N.P., Childress, C., Abeyrathne, B. 2026. Effects of pre-harvest brackish water exposure on leafy green growth in aquaponic systems. Frontiers in Sustainable Food Systems. 10:1833724. https://doi.org/10.3389/fsufs.2026.1833724.
DOI: https://doi.org/10.3389/fsufs.2026.1833724

Interpretive Summary: Aquaponics is the symbiotic culture of fish and plants where the plants act as filters that help maintain good environmental conditions for the fish. Additionally, both the fish as well as the plants can be sold which can potentially lead to higher profits. Typically, freshwater aquaponics are investigated, but in areas close to the ocean, the source water can have elevated salinity. Rather than being seen as an obstacle, brackish water might have some benefits to the plants due to containing various micronutrients. In this study, three leafy plants were cultured in freshwater aquaponics and then 5 days prior to harvest, marine salt was added to increase the salinity to 5 ppt. Results showed that biomass to swiss chard and watercress were negatively affected but not kale. No negative impact was observed in fish (tilapia). Numerically, kale had more biomass as well as micronutrients when the salinity was elevated. Further research on kale as well as fish could be explored on the taste and nutritional value.

Technical Abstract: Growing interest in brackish or saline water aquaponics presents several opportunities for research, one of which is to develop protocols for producers seeking to integrate salt-tolerant non-halophyte crop production within saltier systems. This integration has the potential to produce a better tasting product that is perceived as a higher valued product. However, the negative effects on plant growth often outweigh any economic benefit from a better tasting product. To address this, a single 4-week trial was conducted to evaluate the effects of pre-harvest brackish water (5 ppt) exposure on three different leafy green varieties grown within aquaponic systems. The single trial used six replicated recirculating raft aquaponic systems. Three systems were exposed to 5 ppt of marine salt approximately 5 days prior to the plant harvest (treatment), while the other three systems did not receive any marine salt additions (control). The three leafy greens grown were Kale (Brassica oleracea var. Black Magic), Swiss chard (Beta vulgaris var. Bright Lights), and Watercress (Nasturtium officinale), with each variety having 18 plants/variety/system or a total planting density of 30 plants/m2 of grow area. Plant growth, fish growth, water quality, and environmental data were compared in either system using a two-sample t-test. Significant (p = 0.05) biomass reductions were observed for Swiss chard and Watercress exposed to salt, while Kale exhibited no significant (p > 0.05) differences in biomass when exposed to the salt as compared to the control. All plant varieties within the salt treatment exhibited a highly significant (p = 0.01) increase in both Na and Cl within the plant leaf tissue as compared to the plants within the control. This research demonstrates that the pre-harvest salt exposure aquaponic protocol can be effective for increasing leaf tissue mineral content of certain non-halophyte crops without compromising the yields. Further research on sensory characteristics and antioxidant properties should be evaluated.