A Comparison of Nutritional Value of Lettuce in Vertical Hydroponics and Field Farming Systems.

Vertical Hydroponics (VH) is a farming method that conserves space and water through the use of 3-D shelving and a soilless medium.  Food quality and safety can be further augmented through the use of indoor, sterile, climate-controlled environs.  Such facilities can be built in urban areas, bringing the produce closer to consumers and reducing turnover rates to one day.  This reduction allows less time for crop nutrition to break down, as has been observed.  This study compared the relative nutritional value of lettuce (Letuca sativa L.) grown in both VH and field farms.  Four varieties, ‘LE2005’, ‘S8963’, ‘Frill Ice’, and ‘Klausia’ were grown under VH and field conditions in Kyoto, Japan and Salinas, California, respectively. Specimens were sampled at three separate times from each farming system: at harvest, one day post-harvest, and six days post-harvest.  The post-harvest lettuces were stored under refrigerated conditions.  Lettuce was analyzed by liquid chromatography for several essential nutrients, including Vitamins C and A.  A comparison of the one-day VH lettuce and six-day field lettuce provides an honest reflection of the nutritional value of lettuce available on the market for consumers.