Horticultural Research in Japan. Production of vegetables and ornamentals in hydroponics, constraints and control measures

Japan has a very mountainous topography, steep landforms, and varied climate making it less suitable than other countries for growing horticultural crops. However, good crop production technologies make it possible to grow high quality produce in Japan. The major horticultural crops are mainly produced in greenhouses and high tunnels however, a vast majority of greenhouse systems are outdated. Horticultural production practices could be more sustainable through the use of hydroponics in the greenhouse. Commercial hydroponic systems have proved more productive (20-25% higher) than conventional systems of agriculture. A number of research projects have been conducted to better understand production constraints in hydroponics, such as autotoxicity, and to identify suitable cultivars and supplementation techniques. This review discusses greenhouse production techniques for vegetables and ornamentals in hydroponics, as well as constraints and means for sustainable production.