Testing on Efficiency of Hydroponic Greenhouses

Abstract

Hydroponic vegetable production under a small net-house is a typical crop cultivation promoting the measures to reduce the use of chemical pesticides.  However, vegetable crops in such a conventional hydroponic culture usually face a serious problem of the build-up of heat inside the greenhouse that affects vegetable yields.  The objective of this research was set up to develop hydroponic greenhouses for promoting the production of high quality vegetables.  The design was based on the principle of natural ventilation by providing a ridge vent on the greenhouse structure.  In addition, two supplemental cooling systems were introduced : by covering the roof with black plastic net and by applying a foging system inside the greenhouse.  A series of experiments namely survey, design and greenhouse testing were conducted in order to evaluate the performance of prototype greenhouses in comparison with conventional greenhouses at two different locations: Agricultural Engineering Research Institute, Bangkok and Agricultural Engineering Centre, Chiang Mai. during October 2006 - September 2007.  The results showed that the maximum temperature inside the prototype was approximately 5 C lower than that of conventional greenhouse in the summer.  The increases of vegetable fresh weights were obtained in all locations and cultivation periods.