Comparison of growth, phytochemical content, nutrient uptake, and water consumption of lettuce under two hydroponic system designs: nutrient film technique and deep-water culture

Two hydroponic production system designs (nutrient film technique: NFT, and deep-water culture: DWC) were set up in a climate-controlled greenhouse aiming to investigate differences in growth, nutrient and water uptake patterns, yield and quality of lettuce (Lactuca sativa ‘Butterhead’) between the two systems. The research was conducted from July through August (summer growing conditions) with four system replicates for each hydroponic design and each system contained nine lettuce plants. Throughout the study, photosynthetic properties were higher in NFT-grown lettuce than DWC. Leaf area, fresh yield, and dry yield were higher in NFT by 13.0, 22.8 and 27.7%. All leaf nutrients except calcium and magnesium in shoot tip were within the sufficiency range for lettuce in both systems. In the nutrient solution of both systems, nitrogen, phosphorus and potassium concentrations decreased, while calcium, magnesium, and sulfur concentrations gradually increased throughout the study. There was higher percentage of nitrogen, calcium and sulfur uptake in NFT than DWC by 9.2%, 31.4 and 33.9%. Total chlorophyll and total carotenoid concentrations in NFT-grown lettuce were lower than DWC-grown lettuce by 5.2 and 41.0%, respectively. Total water consumption was 9.6% higher in NFT than in DWC which explains the increased accumulation of some ions in NFT. In conclusion, although 30% yield increase was observed with NFT, total chlorophyll and total carotenoid contents were greater in DWC.