Supplementation of potassium in aquaculture wastewater and its effect on growth performance of basil (Ocimum basilicum L) and pangasius (Pangasianodon hypophthalmus) in NFT-based aquaponics

Abstract

An experiment was conducted for 120 days to optimize the potassium dose and investigate its effects on the growth performance of basil and pangasius in a nutrient film technique-based aquaponics. Potassium was supplemented as four different dosages assigned as T1 (90 mg/L), T2 (120 mg/L), T3 (150 mg/L), and T4 (180 mg/L) were compared to an unsupplemented control (C). Basil and pangasius were stocked at 24 plants/m² and 3.00 kg/m³, respectively. The highest basil yield occurred during the 3rd harvest in T4 (390.50 ± 4.25 g), followed by T3, T2, T1, and control. No significant difference in plant yield was observed between T4 and T3. Similarly, highest plant height, leaf length, leaf width, SFW, SDW, RFW, and RDW was recorded in T4 and T3 compared to control and other treatments. Potassium supplementation resulted in increased uptake of macro-micro nutrients viz., phosphorous, nitrogen, sulfur, potassium, copper, iron, zinc, and manganese in basil. The physico-chemical parameters and nutrient profile of culture water were found to be within the permissible limits for aquaponics. The body weight of fish didn't show any significant difference in control, T1, T2 and T3 while significantly lower body weight was recorded in T4. Significantly higher serum cortisol and glucose levels were found in T4. Considering the basil yield, nutrient and chlorophyll content of basil plant, water quality, body weight of fish, and fish stress parameters, supplementation of 150 mg/L (T3) of potassium was found to be the optimum dose for basil and pangasius culture in NFT-based aquaponic system.