A Study of Controllable Factors that have an Effect on Lettuce Production in a Hydroponic Lettuce Growing System

Hydroponic growing systems (HGS) consist of ideal technology for producing fruits and vegetables that are to be marketed locally. However, there is a difference between a working system and one that is commercially successful. Most HGS are not easy to manage by the inexperienced and the unskilled. Research reports verify the potential for lettuce to be produced both successfully and unsuccessfully. Therefore, many benefits can potentially accrue from continued research efforts to refine inputs to HGS while identifying the risks of improper operation and errant decision making. This paper describes a Hydroponic Lettuce Research Laboratory that was recently constructed at the Ohio Agricultural and Research Development Center (OARDC) in Wooster, Ohio. The water and nutrient delivery system is capable of randomly and simultaneously delivering 16 different treatments to lettuce crops via 16 growing channels supplied by eight recirculation tanks. Specified combinations of growing media, cultivar, solution flow rate, pH, EC and solution temperature were studied during two experiments. A disappointing result was the magnitude of the “within treatment” variation. The overall average mass for lettuce grown during the autumn 2008 experiment was 119.0 grams (wb) per head compared to 161.6 for spring 2009. This increase was attributed to the installation of pH control capability prior to the second experiment.