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¹ Asian Institute of Technology (AIT), School of Environment, Resources and Development (SERD), Aquaculture and Aquatic Resources Management (AARM), Pathumthani, Thailand
² Association Réunionnaise pour le Développement de l'Aquaculture (ARDA) aquaculture research center, L’Étang-Salé-les Bains-La Réunion, France
³ Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), UMR ISEM, F-34398 Montpellier, France DOI : 10.4194/1303-2712-v16_2_11 Viewed : 5347 - Downloaded : 5269 Two experiments were conducted to evaluate the effects of three water recirculating duration (daytime (07.00h to18.00h); nighttime (18.00h to 07.00h); and 24 hours control) and shading (30%, 60% and no shading control), respectively, on growth and sap’s nitrate content of lettuce in a commercial aquaponic system integrated with red tilapia culture. First experiment showed that water recirculating time did not affect the lettuce growth, thus offering the possibility to increase aquaponics profitability by reducing the operational cost. The second experiment revealed that shading affected nitrate content in the sap of the leaf midribs, but it remained in range specified by EU regulations in all treatments. The highest lettuce growth was observed at the rate of 30% shading whereas 60% shading gave the lowest growth (P<0.05). Keywords : Recirculation duration, aquaponic system, lettuce, nitrate, shading