2017 ASHS Annual Conference

Aquaponics is a production system that integrates aquaculture and hydroponics by recirculating residual nutrients resulted from fish waste for cop production. Although many different vegetable crops have been suggested for aquaponics systems, limited information is available on their growth and yield in aquaponics or in comparison to hydroponics. This study was conducted to compare the growth and yield of 10 vegetable crops (pac choi, mizuna, mustard, amaranth, bekana, Swiss chard, chia, basil, lettuce, and tomato) grown in aquaponics in comparison with hydroponics. In aquaponics, fish feed (1% of fish weight) was added as a source of fertilizer for plants, while commercial fertilizer was applied in hydroponics to maintain the electrical conductivity (EC) within the suggested range. Water quality parameters (temperature,°C; pH; conductivity, µS·cm^-1; dissolved oxygen, mg·L^-1) were measured daily. The pH was adjusted using at around 7 and 5.5 for aquaponics and hydroponics, respectively. Water was sampled for total ammonium nitrogen (TAN), nitrite, nitrate, and phosphate every four days. Crop growth parameters were measured weekly, including plant height, leaf length and number, SPAD value, photosynthetic rate (Pn) and leaf temperature. Initial and final fish and vegetable crop biomass was measured. EC in aquaponics increased from 0.7 to 1.4 mS·cm^-1, while EC in hydroponics was maintained at 1.8 mS·cm^-1. Nitrate level in aquaponics increased from 10 to 30 mg/L during 30 days, while it increased from 160 to 250 mg/L in hydroponics. Phosphate concentration in aquaponics increased from 7.2 to 45.2 mg/L, while that in hydroponics slightly increased from 62.4 to 81.9 mg/L. In general, crops in hydroponics showed increasing Pn over time, while in aquaponics, Pn quickly dropped down in the second week, then maintained or further decreased in following weeks, depending on vegetable species. The lower Pn in aquaponics might be partly due to low nutrient availability during the early-production phase. However, there were no significant differences between aquaponics and hydroponics in growth and yield parameters of most vegetable species. These results indicate that, despite the limited nutrient availability in aquaponics, the growth and yield of aquaponically-grown vegetables were not significantly different from hydroponically-grown ones. Crop productivity may be enhanced by increasing nutrition availability during early-production phase in aquaponics.