The use of hydroponics is expanding rapidly. In 1995, the total area being used for hydroponics cultivation was 7. 63 km2 in Japan. Further development and simpler hydroponics cultivation systems are required. We developed 3 new hydroponics cultivation systems; a foam cultivation system, a bubble cultivation system and a coral sand cultivation system.
In the foam cultivation system, the culture solution was foamed by adding PVA, thus lightening the culture bed. In the bubble cultivation system, the growth of crops was improved by supplying an oxygen-supersaturated culture solution. In the coral sand cultivation system, coral sand with high porosity and high gas permeability was used. Since coral sand is alkaline and provides buffer action, pH adjustment was not necessary in this system.
Melon was cultivated by these systems in a greenhouse from summer to fall. Fruit weight, fruit size, leaf length and leaf width for the melon plants were measured at the time of harvest.The values in all criteria examined were higher in the foam and bubble cultivation systems than in the conventional hydroponics system. Nutrient uptake by the melon plants during the cultivation period was high in these 2 systems which likely promoted melon growth.