Lettuce (Lactuca sativa) Production in Northern Latitudinal Aquaponic Growing Conditions

Aquaponics, the combination of hydroponics and aquaculture into one growing system, is a controlled environment production system that potentially has increased environmental and consumer benefits over traditional production methods. There are many different ways to configure aquaponics systems that include different fish species, water circulation, lighting, plant species/density, and more. We tested three cultivars of lettuce, a common aquaponically produced crop, for yield in multiple aquaponic systems and conditions over a 13-month period in Minnesota. Four different aquaponic configurations and four types of fish were tested over the course of the experiment. There was no addition of supplemental nutrients to the systems to evaluate the differences between treatments and set a baseline. There was no difference in yield between lettuce produced aquaponically and those grown in soilless medium. However, there was a difference in yield between lettuce grown with different fish treatments. The tilapia treatment produced higher average yield than yellow perch. There was a difference between cultivars, with higher average yield from loose-leaf bunch cultivars (Salanova, Skyphos) than the bibb type (Rex). Average yield for all but one treatment was above that of reported commercial field production, making lettuce a competitive aquaponic crop in most systems.