LAUSR

BACKGROUND Aquaponics is considered a sustainable system for the production of fish and vegetables. However, little is known about the effects of different system variables on vegetable quality. Hence, the aims of this study were to evaluate the influence of aquaponics on the composition and quality traits of three vegetable species in relation to stoking density of the common carp (Cyprinus carpio L.), in comparison with those of plants grown in hydroponics. RESULTS The highest cumulative vegetable marketable yield was obtained in low density aquaponics (APL), followed by hydroponics (HP) and high density aquaponics (APH). Vegetable quality traits showed species-specific responses. In general, phosphorus concentration was higher in plants grown in APH and lower in those grown in HP, while the opposite was observed for nitrate concentration. In lettuce (Lactuca sativa L.), sugar content was the highest in APH, whereas in Swiss chard (Beta vulgaris L. subsp. vulgaris Cicla group), the AP treatments increased only glucose content. No differences in sugar content were observed in Catalogna (Cichorium intybus L. Catalogna group). The lowest and highest phenolic acid concentrations in the aboveground biomass of Catalogna and lettuce were observed in HP and APH treatments, respectively. In Swiss chard, APH treatment resulted in the highest caffeic acid content, whereas the ferulic acid was the highest in HP. CONCLUSION Aquaponics at low stocking density increased plant yield, compared to HP, without compromising vegetable quality, whereas aquaponics at high stocking density improved vegetable quality, but at the expense of yield. This article is protected by copyright. All rights reserved.