Lettuce (Lactuca sativa L. var. Sucrine) Growth Performance in Complemented Aquaponic Solution Outperforms Hydroponics

TLDR

Hydroponic systems are known to optimize lettuce growth, yet the comparative benefits of aquaponics—especially when aquaponic solutions are enriched with minerals—remain underexplored, despite evidence that microorganisms and dissolved organic matter in recirculating aquaculture system water may enhance root and shoot development. Lettuce was cultivated in AeroFlo installations using three treatments: hydroponic, aquaponic, and mineral‑enriched aquaponic solutions. The study found that while hydroponic and aquaponic treatments produced comparable growth, the mineral‑enriched aquaponic (CAP) treatment increased shoot weight by 39% and root weight was higher than hydroponic, highlighting the positive impact of recirculating aquaculture system water and supporting the development of decoupled aquaponic systems as a more productive alternative.

Abstract

Plant growth performance is optimized under hydroponic conditions. The comparison between aquaponics and hydroponics has attracted considerable attention recently, particularly regarding plant yield. However, previous research has not focused on the potential of using aquaponic solution complemented with mineral elements to commercial hydroponic levels in order to increase yield. For this purpose, lettuce plants were put into AeroFlo installations and exposed to hydroponic (HP), aquaponic (AP), or complemented aquaponic (CAP) solutions. The principal finding of this research was that AP and HP treatments exhibited similar (p > 0.05) plant growth, whereas the shoot weight of the CAP treatment showed a significant (p < 0.05) growth rate increase of 39% on average compared to the HP and AP treatments. Additionally, the root weight was similar (p > 0.05) in AP and CAP treatments, and both were significantly higher (p < 0.05) than that observed in the HP treatment. The results highlight the beneficial effect of recirculating aquaculture system (RAS) water on plant growth. The findings represent a further step toward developing decoupled aquaponic systems (i.e., two- or multi-loops) that have the potential to establish a more productive alternative to hydroponic systems. Microorganisms and dissolved organic matter are suspected to play an important role in RAS water for promoting plant roots and shoots growth.