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ARS Home » Midwest Area » Wooster, Ohio » Application Technology Research » Research » Research Project #436775

Research Project: Optimum Nutrient Management for Leafy Green Production in Hydroponic Systems

Location: Application Technology Research

Project Number: 5082-21000-001-18-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Jul 29, 2019
End Date: Jul 28, 2021

Objective:
The proposed research aims to address the existing production issues in hydroponic leafy greens via nutrient management.

Approach:
The project will be conducted using the Nutrient Film Technique in growth chambers and greenhouses at the cooperator's facilities. Objective 1: Investigate the influence on yield and quality of leafy lettuce growing under varied EC levels in response to high and moderate temperature and humidity variations. Objective 2: Identify the influence on nutrient uptake and water use under varied EC levels in response to high and moderate temperature and humidity variations. Eight benches of Nutrient film technique (NFT) comprised of six growing channels capable of growing 36 plants will be used. The experiment will be conducted in two different growth chambers with systems comprised of four different EC levels (1.4, 1.6, 1.8 or 2.0 mS/cm). pH (5.8) will be maintained at the constant level throughout the experiment. Growth and development under these varying EC levels will be investigated under two different temperatures, 70°F and 90°F in two different growth chambers at 50% relative humidity. The experiment will then be repeated at 80% relative humidity. Hence, there will be three environmental variables; temperature, relative humidity and electrical conductivity. Yield, in terms of fresh weight per head and dry weights will be measured at harvest. Weekly measurements of photosynthesis and transpiration rates will be taken from plants. Plant tissue analysis will be conducted to investigate the variations in nutrient uptake under different EC, temperature and humidity. Objective 3: Identify the fluctuations in yield and quality of leafy lettuce growing under varying EC levels to seasonal environmental variations in a greenhouse during a given year. Lettuce will be grown under greenhouse conditions located at Wooster. The NFT channel system consists of 18 channels and 8 separate solution tanks under four different EC levels (1.4, 1.6, 1.8 or 2.0 mS/cm). Each channel has the capability to grow 18 plants. Channels will be connected randomly to stock tanks. Experiment will be repeated with or without supplementary lighting to cater different greenhouse conditions in Ohio. Data loggers will be connected to record full spectrum solar energy, PAR, daily light integral, temperature and relative humidity in the greenhouse. Data collection from plants will be as per above. Objective 4: Identify the optimum pH and EC recommendations for arugula, watercress, mustard green, kale, sorrel, spinach, bokchoy, Chinese cabbage. The NFT channel system consists of 18 channels and 8 separate solution tanks under four different EC levels (1.4, 1.6, 1.8 or 2.0 mS/cm) will be set up under greenhouse conditions. Each channel has the capability to grow 18 plants. Channels will be connected randomly to stock tanks. Experiment will be repeated by growing crops under four different pH levels (5.8, 6, 6.2 6.4).