Effect of Aquaponic vs. Hydroponic Nutrient Solution, Led Light Intensity and Photoperiod on Indoor Plant Growth of Butterhead, Romaine and Kale (L. sativa, B. oleracea)

Abstract

Effect of Aquaponic vs. Hydroponic Nutrient Solution, LED Light Intensity and Photoperiod on Indoor Plant Growth of Butterhead, Romaine and Kale (L. sativa, B. oleracea) Sean Foster Vertical farming has been proposed as a solution for providing food security for an increasing, urbanized human population. Light-emitting diode (LED) technology has become increasingly affordable and efficient, making it an ideal choice as artificial lighting for indoor farms. Still largely undiscovered parameters are the optimal plant varieties and types of production systems for plant growth, profit, and human nutrition. Aquaponics may be able to provide sustainable animal protein for vertical farms, increasing their ability to provide more substantial nutrition to consumers. This research aimed to better understand vertical farming as a food production system, and to determine if aquaponics can be an appropriate and applicable fit for it. The experiment was a randomized, factorial design with three independent variables: (1) LED photoperiod interval (2) LED-plant distance, and (3) nutrient solution, as well as several dependent variables to assess both plant yield and quality. A 4-tiered shelving unit was constructed for nutrient film technique (NFT) plant production, and treatments were assigned to each row: (1) LED experiment: Row A, 12/12hr reduced photoperiod with adjustable LEDs 4in. above plant surface; Row B, 2/1hr altered photoperiod interval relative to the control; Row C (control), 16/8hr "standard" photoperiod. (2) Nutrient experiment: Row C, aquaponic nutrient solution; Row H, hydroponic nutrient solution. Rows C and H had matched photoperiod and light intensity. Kale from Row A had significantly lower fresh and dry plant yield relative to the control, Row C (p<0.05). Hydroponic romaine, Row H, had significantly higher plant yield relative to aquaponics, Row C (p<0.05). Butterhead yields were not significantly different in any treatments (p>0.05). Future research may implement a larger sample size of only one plant variety, harvest plants earlier, limit light intensity variation, effectively "balance" the aquaponics system, and have more measures of plant "quality." v ACKNOWLEDGMENTS I would first like to thank my advisor, Dr. Greg Schwartz, for his support and guidance throughout the project; you were the best mentor I could have ever asked for. I also thank my committee members Dr. Peter Livingston and Dr. Sara Kuwahara for their insight and help in designing and executing my experiment. To Megan, Jack, and about a dozen other students who helped me count and measure leaves for hours…you saved my life. Professor Smith and Lindsey, thank you so much for helping me organize and analyze all of my data. I would also like to acknowledge the Cal Poly BRAE department, which provided so many resources for construction, operation and maintenance of the system for the experiment. The Fruit Grower's Laboratory (FGL) in San Luis Obispo was extremely generous in doing all water quality and tissue samples pro bono, all in the name...

Reaching the highest shelf: A review of organic production, nutritional quality, and shelf life of kale (Brassica oleracea var. acephala)

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Does green vertical farming offer a sustainable alternative to conventional methods of production?: A case study from Scotland

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