This study was conducted to investigated the changes in the nutrient components (NO3 --N, NH4 +-N, PO4 3-P, K+, Ca2+, and Mg2+) and environmental parameters (electrical conductivity, total dissolved solids and pH) on the leaf lettuce (Lactuca sativa L.) grown with hydroponics. Recirculating hydroponic cultivation system was consisted of planting port, LED lamp, water tank, and circulating pump for hydroponic. Nutrient solution was used in the standard solution for Japan vegetables experimental station and commercial hydroponic. The result showed that electrical conductivity (EC), total dissolved solids (TDS) and pH, depending on the growth of lettuce decreased continuously. With the growth of the lettuce, nitrate nitrogen, ammonia nitrogen, phosphate phosphorus were required for periodic replacement. The number of pH compensation due to the growth of lettuce are the most high. The concentration of Ca2+ and Mg2+ during the lettuce growth showed no significant change. However, K+ concentration increased due to the replacement with nitrogen and phosphorus. Electric conductivity and total dissolved solids with total nutrient concentration showed the linear relationship and the correlation coefficient R2 were 0.8601 and the 0.827, respectively.

Abstract
 1. 서 론
 2. 재료 및 방법
  2.1. 실험재료 및 실험방법
 3. 결과 및 고찰
  3.1. 식물 성장
  3.2. 상추 성장에 따른 양액의 전기전도도, 총용존고형물및 pH 변화
  3.3. 상추 성장에 따른 질소, 인 및 양이온 농도 변화
  3.4. 시간에 따른 물 보충량
 4. 결론
 REFERENCE

• 김동석(대구가톨릭대학교 환경과학과) | Dong-Seog Kim (Department of Environmental Science, Catholic University of Daegu)
• 박영식(대구대학교 기초교육대학) | Young-Seek Park (DU University College, Daegu University) Corresponding author