Effects of Renewal Pattern of Recycled Nutrient Solution on the Ion Balance in Nutrient Solutions and Root Media and the Growth and Ion Uptake of Paprika (Capsicum annuum L.) in Closed Soilless Cultures

Ion imbalance in recycled nutrient solutions is caused by selective ion uptake of plants, which occurs at differentrates in different growth stages. The objectives of this study were to investigate the ion balances in both recycled nutrientsolutions and rockwool media using different renewal patterns for the nutrient solutions, and to analyze the subsequent effectson uptake of water and nutrients. Over 12 weeks of paprika cultivation, two different renewal patterns (week units) of 6-4-2and 8-2-2 weeks were compared with a constant renewal pattern of 4-4-4 weeks (control). The nutrient solution in the reservoirtank was constantly maintained at EC 2.5 dS･m-1and pH 5.5-6.5. The changes in the ion balance with the 4-4-4 week patternwere smaller than those with the other treatments. In the early growth stage, however, the ion balances similarly changedamong all treatments. Greater changes were subsequently observed for the 6-4-2 week pattern. Although fruit yield and shootfresh weight of paprika were the lowest with 6-4-2 renewal pattern, no significant differences were observed. Our results indicatethat renewal intervals can be extended in consideration of growth stage for more efficient and practical operations in closedsoilless cultures. KCI Citation Count: 2