Abstract: The different concentrations of potassium dihydrogen phosphate(KH2PO4) on the water quality and the growth of fish and vegetables in the aquaponic system were studied by controlling the KH2PO4 content added. Jade perch and strawberry were selected as experimental objects, and one control group and three treatment groups were set up, with KH2PO4 concentrations of 0, 100, 200, and 400mg /L respectively. The changing trend of three state nitrogen, active phosphorus and potassium ion concentration in the system and the growth performance of gem perch and strawberry were compared and analyzed under different groups. The results showed that different concentrations of KH2PO4 had no significant effect on the basic water quality such as water temperature, pH, dissolved oxygen and the concentration of three-state nitrogen in the aquaponic system. The contents of active phosphorus and potassium ions in the system were positively correlated with the concentration of KH2PO4; When the concentration of KH2PO4 was 200 mg / L, the weight gain rate of jade perch reached maximum, and when the concentration was 400 mg / L, the weight and height gain rate of strawberry reached maximum while the weight gain rate of jade perch decreased. The results showed that adding KH2PO4 to the aquaponics system could promote the growth of jade perch and strawberry, and when the concentration of KH2PO4 is 200 mg / L, the aquaponic system showed the optimal productivity.

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