System management of Lemna minor in aquaponics

In farming, sustainability together with food safety is one of the main objectives to be achieved. Aquaponics is a technique that combines aquatic animals, such as fish, with the hydroponic production of plants that function as biological filters. The proper functioning of the system is based on the dynamic balance of the elements that make it up. Several studies confer aquatic macrophytes such as L. minor, great attributes, highlighting their use for feeding different species. Unfortunately, there is very little information on the system management of macrophytes in aquaponics. To determine the appropriate management parameters for the cultivation of L. minor integrated into the production of Oreochromis niloticus, in aquaponics, three experiments were carried out to evaluate the effect of the hydraulic retention time (HRT), the planting density, plant dissemination and the balance of nutrients in the systems. The results show that the highest biomass production and plant growth are achieved with high flow rates and short HRTs. Planting density has a direct effect on the behaviour of the plant. Regarding the balanced budget, between 7% and 8% of the nutrients (input in dry matter, N and P) are retained by L. minor, keeping the water quality within adequate limits for tilapia production.

Automated summary

Aquaponics combines aquatic animals with hydroponic plants, with studies showing the great attributes of aquatic macrophytes for feeding different species. However, there is limited information on managing macrophytes in aquaponics. High flow rates and short HRTs contribute to the highest biomass production and plant growth, while planting density directly affects plant behavior. Retaining around 7-8% of nutrients in water by aquatic macrophytes can keep water quality within suitable limits for fish production.