Nutrient:plant ratio in integrated production of Nile tilapia and lettuce using FLOCponics
摘要
FLOCponics integrates the principles of aquaponics and biofloc technology (BFT), combining both approaches within a sustainable production framework. Lettuce is a suitable plant species for this system due to its high adaptability and short production cycle. However, production success is strongly influenced by feed management throughout the cultivation period, making it essential to determine optimal nutrient ratios that maximize plant performance while maintaining water quality. This study aimed to identify the most appropriate nutrient ratio to enhance plant development while simultaneously promoting BFT sustainability and vegetable production efficiency. The experimental units consisted of two interconnected tanks (370 L and 100 L): one for rearing Nile tilapia juveniles (21.0 ± 0.45 g; 30 fish per tank) and the other serving as a water reservoir. Twelve units were assigned to three feeding-rate treatments 6.25, 3.12, and 1.56 g of feed per plant per day with four replicates per treatment. Lettuce was cultivated using the nutrient film technique (NFT). Water quality parameters, including dissolved oxygen, temperature, pH, ammonia, nitrite-nitrogen, nitrate-nitrogen, orthophosphate, and alkalinity, were monitored weekly. After 29 days of cultivation, fish performance was not adversely affected by the treatments. In contrast, floc volume and alkalinity differed significantly among treatments. The highest total lettuce biomass was observed at 1.56 g/plant/day (267.74 g), whereas the highest mean final plant weight was achieved at 3.12 g/plant/day (20.82 g). This treatment also exhibited the greatest phosphorus retention. Therefore, a feeding rate of 3.12 g/plant/day at a planting density of 8 plants/m2 provided the best balance between lettuce productivity and the sustainability of the FLOCponic system.