In this study, we tested local heating using hung plastic air ducts (0.5 m or 1.5 mheight from ground surface) and measured air and soil temperatures and soil heat fluxin order to confirm that the local heating reduces energy consumption compared withconventional heating by air ducts laid on pathways. On greenhouse tomato production inwinter, heating using a higher arrangement of plastic ducts consumed less energy owingto larger low temperature areas below the air ducts. Soil temperature and soil heat fluxwere significantly higher under the laid air ducts in conventional heating than in otherpositions and air duct arrangements, whereas the decrease was more drastic the furtheraway from plastic ducts. Heating using hung air ducts hardly affected soil temperatureand soil heat flux and there was no difference between the heights of 0.5 m and 1.5 m.Estimation of soil heat flux in the entire greenhouse revealed that a quarter of the energyreduction was derived owing to the hung air ducts. Furthermore, the higher arrangementof plastic ducts tended to reduce the contribution of soil heat flux to energy reduction.Since the equipment of greenhouse in this study was simple (single layer plasticfilm, no thermal screens), adding a thermal retention system can increase the contributionof soil heat flux. Adversely, lower outer temperature would decrease that contribution.
The use of sea transportation is desirable for reducing the transportation cost of strawberry exports. However, because Kyushu does not have a large-scale container terminal, it is difficult to transport strawberries directly overseas by sea. Therefore, we examined the possibility of exporting strawberries from Kyushu by combining shipping with air transportation from Okinawa to the Asian continent. In a laboratory storage test, storage in modified atmosphere packaging for 10 days did not affect the fruit quality of strawberries. In a sea and air transportation test from Kyushu, the quality of ‘Koiminori’ fruits that were not stored in modified atmosphere packaging were similar to the quality of those transported by sea immediately after arrival in Hong Kong and higher than the quality of those transported by sea a few days after arrival. In addition, storage for 1 to 2 days during air-sea transshipment did not affect fruit quality after arrival in Hong Kong. The combination of sea and air transportation was superior to sea transportation alone in terms of shelf stability and flexibility of storage during transportation and was effective for the export of strawberry fruits from Kyushu to Asia.