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About the Cover

Vol. 89 No. 10 (2013)

Vol. 89 No. 10 (2013)

Plant factory: Closed plant production system with artificial light

  There are about 150 plant factories (PF) or closed plant production system with artificial light (CPPS) in Japan as of October 2013 and its number has been increasing since 2009. The PFs are mainly used for commercial production of leaf vegetables with no use of pesticides. Photo A is the inside view of a PF (floor area of culture room being 338 m2, 10 tiers and 9 rows) built in Kashiwa-no-ha Campus of Chiba University. Production capacity is about 3,000 leaf lettuce heads per day or over 3,000 heads/m2 (floor area) per year. Leaf lettuce seedlings raised in the PF with 4 unfolded leaves (Photo B, 25 days after seeding) are grown to harvestable size (Photo C, ca. 75 gram per head) 10 days after transplanting, resulting in around 35 crops per year on the culture panel. The lettuce heads each in a sealed plastic bag are sold at a supermarket 500 m apart from the PF (local production for local consumption). While, when grown in the open fields of a temperate climate region, it takes around 40-50 days from transplanting to harvesting with 2-3 crops per year, resulting in annual production of 50-60 heads (ca. 200 gram each)/m2 (land area) per year. Recently, researches on environmental and nutritional control for reducing potassium content and/or enriching Vitamin C, sugar content and other functional components in leaves have been conducted extensively. Dr. Kozai and his colleague, as reviewed in this issue (pp. 447-461), analyzed the energy and mass balance of CPPS and provided the methods of improving resource use efficiencies in terms of electric and light energy, H2O, CO2 and inorganic fertilizer, which are essential resources for growing plants in the CPPS. (Photos A-C: by courtesy of Mr. Shigeharu Shimamura, Mirai, Inc.)

Toru Maruo
Professor of Chiba University, Japan

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