Abstract
Tomato (Lycopersicon esculentumMill., cv. Momotaro) plug transplants were grown in a closed-type (CTPS) and an open-type (OTPS ; i.e., greenhouse) transplant production systems during summer (11-15 August to 1 September, 2000) . The quality of transplants and water consumption in the CTPS were compared with those in the OTPS. Electric energy consumption per transplant was estimated in the CTPS. The CTPS was a system designed to produce transplants under artificial light in a relatively airtight structure with thermally insulated walls, and to produce high quality transplants using minimal resources. The CTPS employed a sub-irrigation system. Air temperature in the CTPS was maintained at 28°C during a 16 h photoperiod and at 19°C during an 8 h dark period by using an air conditioner. The OTPS employed an overhead irrigation system. Air temperature in the OTPS was partly controlled by using roof and side ventilators, but varied from 23 to 43°C depending on the weather conditions. The quality of transplants was higher in the CTPS than in the OTPS. Electric energy consumption per transplant in the CTPS was 0.7 MJ (0.2 kWh), which corresponded to a cost of 2.9-3.2 Japanese Yen. The amount of water consumed during the transplant production period in the CTPS was 1/12-1/16 of that in the OTPS. These results suggested that value-added transplants could be produced at a lower water consumption of resources in the CTPS than in the OTPS at low electricity consumption.
