Abstract
The paper discusses the feasibility of using hydroponic techniques in the year-round production of high-quality vegetables in ROC on Taiwan. In order to increase the vegetable supply during the summer, with its unpredicable weather conditions, and to meet the requirements for hygienic vegetables, the dynamic root floating (DRF) hydroponic technique was developed at the Taichung District Agricultural Improvement Station in 1986. The DRF technique is based on the use of a low typhoon-proof greenhouse with a framework of piping, a ridged culture bed, concave panels, an aspirator, a nutrient level adjuster, a nutrient exchange box and a nutrient concentration controller. Over the hot summer season, the DRF technique reduced the build-up of heat in the greenhouse, and induced plants to develop an aeroroot system to overcome the shortage of dissolved oxygen in the nutrient solution. There are now more than 19 ha of DRF hydroponic vegetable factories run by 150 growers in Taiwan, and another 0.6 ha in various parts of Thailand, Malaysia and Singapore. This paper mainly focusses on how the DRF technique makes possible the successful year-round production of leafy vegetables in tropical and subtropical areas.