Merle H. Jensen
Controlled Environment Agriculture Center
University of Arizona
Tucson, AZ 85721

Keywords: Hydroponics, leafy vegetables, Mesclun

Abstract:In 1976, a method of growing lettuce and other leafy vegetables on a floating raft of expanded plastic was developed independently by researchers at the University of Arizona and the University of Pisa in Italy.  Today large scale facilities exist in the United States, in the Caribbean, Japan, Mexico and Canada. Termed ADeep Flow Hydroponics, @ the system consists of horizontal, rectangular shaped tanks lined with plastic and filled with nutrient solutions.  Those developed in Arizona measured 4m x 70m, and 30cm deep.  This method of hydroponics continues to grow in popularity due to the ability to control root temperatures, either by heating the nutrient solutions or chilling the solutions to reduce bolting, especially important in tropical and desert regions of the world.  Concurrent with the development of the production system, were packaging and marketing experiments.  Packaging individual heads in air-sealed plastic bags extended the shelf-life up to three weeks, plus provided protection during transportation.  Today, with the introduction of new specialty, leafy vegetables as those common in Mesclun (a variety of tender leafy salad greens) a renewed interest has been created in deep flow hydroponics.

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