Growth, phytochemical concentration, nutrient uptake, and water consumption of butterhead lettuce in response to hydroponic system design and growing season

Authors: YANG, TENG - THE OHIO STATE UNIVERSITY; SAMARAKOON, UTTARA - THE OHIO STATE UNIVERSITY; Altland, James

Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2024
Publication Date: 4/13/2024
Citation: Yang, T., Samarakoon, U., Altland, J.E. 2024. Growth, phytochemical concentration, nutrient uptake, and water consumption of butterhead lettuce in response to hydroponic system design and growing season. Scientia Horticulturae. 332. Article 113201. https://doi.org/10.1016/j.scienta.2024.113201.
DOI: https://doi.org/10.1016/j.scienta.2024.113201

Interpretive Summary: Lettuce is a major fresh product in many countries and one of the year-round popular vegetables in U.S. Nutrient film technique (NFT) and deep water culture (DWC) are the most prevalent types of hydroponic systems for the production of leafy greens. Few studies involved hydroponic production compared quantity, quality, or efficiency of production between different systems. The objective of this study was to identify the nutrient and water uptake patterns as well as yield and quality of lettuce grown in NFT and DWC systems under different growing seasons and provide instructive data for the development of specific production standards between growing systems for researchers, and to aid decision-making process related to hydroponic system choices. The research was conducted with four system replicates for each hydroponic design and each system contained nine lettuce plants. Plant photosynthetic properties, growth parameters, and irrigation solution nutrient concentrations were measured weekly. At the end of the production cycle, plants were harvested for leaf area, fresh and dry yield of shoots and roots, nutritional and phytochemical concentrations. There were fewer seasonal fluctuations in DWC system than NFT system under fall and summer seasons for Butterhead lettuce production. DWC grown lettuce showed less severe tipburn symptom as a better marketable quality indicator. During fall, DWC performed better than NFT with respect to increased yield, enhanced total carotenoids and vitamin C as well as non-acidified phenol concentrations. Water consumption is significantly greater in NFT as compared to DWC in both seasons. Further study is needed to compare the performance of different lettuce cultivars and optimize nutrient management plan for hydroponically grown lettuce based on type of the system.

Technical Abstract: Two hydroponic system designs (nutrient film technique: NFT, and deep water culture: DWC) were set up in a climate-controlled greenhouse to compare growth, nutrients and water uptake patterns, yield and quality of lettuce (Lactuca sativa cv. Butterhead) during fall (October through November) and summer (July-August) growing conditions. The research was conducted with four system replicates for each hydroponic design and each system contained nine lettuce plants. Plant photosynthetic properties, growth parameters, and irrigation solution nutrient concentrations were measured weekly. At the end of the production cycle, plants were harvested for leaf area, fresh and dry yield of shoots and roots, nutritional and phytochemical concentrations. In the study, DWC system had better water quality properties than NFT including less seasonal water temperature fluctuation, which supported lettuce with better photosynthetic rates, growth rate and fresh yield in fall. Tipburn symptom were only observed in summer, and NFT grown lettuce had significantly lower shoot calcium and magnesium concentrations than DWC in both fall and summer seasons, which led to more severe tip burn symptom in summer. In addition, better water quality in DWC also benefited lettuce with higher antioxidant concentrations than NFT, which included 9.4% higher vitamin C in fall, 34.6% higher total carotenoids in fall, 40.6% higher non-acidified phenols in fall, as well as 12.9% higher total chlorophyll in summer. Although there were marginal differences in fresh yield, most types of mineral nutrients and antioxidants between DWC and NFT, DWC performed better than NFT with less tipburn in summer as well as increased yield, total carotenoids, vitamin C and non-acidified phenols in fall.