Arugula and Lettuce Responses to Greenhouse Hydroponic Systems: An Analysis of Yield and Resource Use Efficiencies

Abstract

Controlled environment agriculture (CEA) for leafy green production is growing in popularity as consumers and producers become more environmentally conscious. Growers can use several hydroponic systems in CEA leafy green production, but detailed information about their tradeoffs is scarce. In this experiment, we sought to grow leafy greens in several soilless systems to evaluate yield and resource use and determine optimal production systems. Arugula (Eruca sativa ‘Astro’) and lettuce (Lactuca sativa ‘Casey’) were grown in a greenhouse in four soilless systems: deep water culture (DWC), nutrient film technique (NFT), vertical tower, and aeroponics. System resource inputs in terms of water, energy, and area, as well as system plant outputs like biomass production and nutrient concentrations were quantified during the 28-day experiment. Water (WUE), energy (EUE), and area use efficiencies (AUE) were then calculated using fresh shoot biomass. Based on these resource use efficiencies (WUE, EUE, and AUE), arugula had excellent performance in aeroponics, satisfactory performance in both the NFT and vertical systems, and comparatively poor performance in DWC. Lettuce performed satisfactorily in both DWC and NFT, but both systems had reduced EUE, and DWC also had reduced AUE. In contrast, lettuce had fair performance in the vertical and aeroponic systems. In conclusion, arugula is optimally grown in aeroponics, and lettuce is optimally grown in DWC or NFT. Understanding these system tradeoffs will help growers and the CEA industry to become more sustainable and profitable.