This experiment was aimed to identify concentrations of mineral nutrients in leaf lettuce (Lactuca sativa) grown on hydroball aquaponics and in the water for growing fish by conducting two experiments. The experiment I (Expt. I) was conducted with 12 fishes (F12) with and without filter, hydroball and plants (H12 (12 fishes, hydroball), FHP12 (12 fishes, filter, hydroball, 6 plants) and HP12 (12 fishes, hydroball, 6 plants)), and the experiment II (Expt. II) was with and without plants (FH15 (15 fishes, filter, hydroball), FHP15 (15 fishes, filter, hydroball, 6 plants)). The pH level in the water of all the treatments was decreased during the growing period, and the pH and EC of the water were lower in all the treatment with plants than those without plants in both Expt. I and Expt. II. When compared with adequate nutrient concentrations for hydroponics, nitrate nitrogen (NO3-N) and phosphorus (P) concentrations in the fish growing water were higher under the FHP15 treatment in Expt. II; however, potassium (K), calcium (Ca), and magnesium (Mg) were only 16, 49, and 82% of hydroponics, representatively, and iron (Fe) was not detected. The fresh weight of lettuce harvested from the FHP15 treatment was 38 g, only a 30% of marketable lettuce yield. The T-N and P contents of the leaf tissue grown under the FHP15 treatment were close to the optimal level; however, the K, Ca, and iron (Fe) contents were less than the optimal with no deficiency symptom.

풋고추의 육묘관리시에 최적 시비농도를 구명하기 위하여 무기이온을 농도별로 처리한 다음 식물체의 생육과 광합성에 미치는 효과를 조사하였다. 초장은 무기이온의 농도가 증가할수록 길었으며, 표준농도인 1.0배를 시비한 것보다 2.0배의 고농도로 시비하였을 때에 ‘녹광’은 72%, ‘꽈리’는 18% 신장생장이 촉진되었다. 건물중은 ‘꽈리’의 경우에 무기이온의 농도가 높을수록 증가하였으나, ‘녹광’의 경우에는 고농도인 2.0배 처리시에는 오히려 감소하였다. 엽록소의 함량은 무기이온의 농도가 2.0배까지 높을수록 증가하였다 광합성속도, 기공전도도 및 증산속도는 두 품종 모두 1.5배의 농도로 관주하였을 때에 가장 높았는데, 이때의 광합성속도를 비교하면 ‘녹광’은 8.74μmol.m-2 s-1, ‘꽈리’는 5.10μmol.m-2 s-1로서 생육이 왕성하였던 ‘녹광’의 광합성속도가 더 높았다.