Increasing Efficiency of Aeroponic Vegetable Production
The adoption of soilless culture in controlled environment agriculture (CEA) has gained popularity in recent years. Innovative technologies have aided in the advancement of CEA. Hydroponically grown produce is widespread in the industry today, but this method of growing uses large quantities of water in order to bring a production facility online. While this is often less than field production, other options can further increase water use efficiency in CEA. Aeroponic crop production could be the solution because it has shown promising results in increasing resource efficiency. However, there is no standard for designing, building, and best practices within aeroponic production systems today. Therefore, the objective of this study was to design and build an aeroponic system and track lettuce growth and development in deep water hydroponic and aeroponic systems. Then determine if by decreasing the spray durations within an aeroponic system, can we maintain lettuce yield while reducing the total water and nutrients used compared to a deep-water hydroponic unit. Plant physiological data on aerial and root tissues were collected throughout these experiments. Data showed that aeroponically produced lettuce had larger yields, increased root development, and higher CO2 assimilation. Furthermore, head weight was 60% greater in the aeroponic production systems during the first experiment. Roots were analyzed using WinRhizoPro, which showed that aeroponically produced plants had more roots in the fine and very fine classifications than hydroponically produced plants. To analyze optimal spray durations, we adjusted durations to 100% (30 sec on 5 minutes off), 75% (22.5 sec on 5 minutes off), and 50% (15 sec on 5 minutes off) for Trial 1 and 100% (15 sec on 5 minutes off), 75% (11.25 sec on 5 minutes off), and 50% (7.5 sec on 5 minutes off) for Trial 2 for the second experiment. This study found that a spray duration of 30 sec, 22.5 sec, and 15 sec produced plants with higher yields, longer roots, and increased Nutrient Uptake Efficiency (NUE) compared to the hydroponic system. A decrease in plant vigor was observed at a 7.5 sec spray duration, leading to smaller plants, lower NUE, and decreased chlorophyll concentrations. Therefore, we conclude that while all but the aeroponic 7.5 sec spray duration outperformed the hydroponic system, the spray durations within the aeroponics systems were similar in yield and resource use efficiencies.
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