Salt Level in a Simulated Aquaponic System and Effects on Bibb Lettuce

ABSTRACT

Aquaponics is the integration of plant and fish production where byproducts of one system are used as an input for the other. In an integrated system of tilapia (Oreochromis spp.) and Bibb Lettuce (Lactuca sativa L.), it is a common practice to add salt (NaCl) to the water to ease stress on fish. This study was undertaken to determine the tolerance of hydroponic Bibb lettuce to various chloride concentrations from addition of NaCl to the hydroponic solution. In Experiment 1, lettuce plants were grown hydroponically in 6-L buckets with standard hydroponic fertilizer and NaCl concentrations ranging from 0 to 500 mg·L⁻¹ chloride. Approximately 30 days after transplanting, at maturity, plants were not adversely affected by any of the treatments. In Experiment 2, NaCl treatments ranged from 0 to 20,000 mg·L⁻¹. Treatments of NaCl concentrations over 5000 mg·L⁻¹ chloride were lethal to lettuce. Adverse effects were seen at concentrations above 2000 mg·L⁻¹. With increasing worldwide fish–vegetable aquaponic systems, producers should monitor and be aware of salt thresholds from the fish system and the resulting effect on the vegetable crops.

KEYWORDS:

• Lactuca sativa
• Aquaponics
• NaCl
• Hydroponics

Funding

This work was supported by the Alabama Agricultural Experiment Station.

Additional information

Funding

This work was supported by the Alabama Agricultural Experiment Station.