Taikichi Takano

Control Measure Against the Injury of Lettuce Seedlings Caused by Salt Accumulation on Polyurethane Cube Surface Used as Root Substrate in Hydroponics.

レタスの水耕栽培において, 子葉や茎頂がキューブ表面に長期間触れることにより生育障害が発生した.本葉が4枚展葉するまでに子葉がダメージをうけると収量が低下した.この障害により収量が低下するばかりでなく, 成長量の個体問格差が増加した.生育障害は, キューブ上部面に水耕液が蒸発してできた高濃度の集積塩に子葉や茎頂が接触することにより発生すると考えられた.キューブの表面に被覆処理することでこれらの障害を回避できた.植物工場等の高度施設栽培では, 計画的生産を阻害する要因を徹底的に除去することが重要である.さらに, 個々の植物の成長を極大化かつ均一化する栽培技術とともに, 生産の管理技術として生育異常を早期に検知するための成長モニター技術も重要であると考える.

The Effects of Blue- and Red-Light Irradiation during Morning Twilight on Perilla Seedling Growth under Artificial Lighting Conditions.

We examined the photomorphogenesis of Perilla frutescens Britton var. japonica Hara seedlings treated with supplemental lighting of blue- and/or red-light in the morning twilight to improve the efficiency of lighting.Perilla seedlings were grown hydroponically at temperatures of 25/21°C (D/N) in a natural light growth room (Koitotron; S-203W). Supplemental blue and/or red lighting (18.8 and 33.5 μmolm-2 s-1 in PPFD) were applied for two hours in the morning twilight.After 33 days of treatment with blue- and/or red-light in the morning twilight, the fresh weight, leaf area and stem diameter of the seedlings were increased. Stomatal density on the upper surface of the leaf also increased. Stomatal density on the upper surface of the leaf was increased by 43.5% with blue-lighting as compared with that of control plants grown without supplemental lighting. The average stomatal opening was 2-fold the wider in the plants treated with blue-light as compared with controls.The stomatal conductance, transpiration rate and photosynthetic rate after 26 days of treatment were also greater in the plants grown with supplemental blue-light.In conclusion, supplemental blue-lighting in the morning twilight is considered to be effective for perilla seedling growth. Supplemental blue-lighting can be utilized for bio-nursery facilities to increase efficiency of plant production.

Development of An Automatic Growth Monitoring system for Vegetables Grown in A Plant Factory.

In the intentional production of crops in a plant factory, it is necessary to measure the progress of growth of an individual plant. There is a significant positive correlation between several growth indices obtained by image processing and the top fresh weight of lettuce plants (Lactuca sativa L. non-heading type) grown in a plant factory. The horizontal projected leaf area for several days after sowing made it possible to estimate the top fresh weight. Therefore, we have developed an automatic plant growth monitoring system for vegetables grown in a plant factory. This system is organized into five parts, CCD camera with a transfer mechanism, a personal computer for image processing CPU, a image memory unit, a TV monitor and a printer. To evaluate the growth of transplants individually, we have developed growth prediction function with fuzzy inference.Using this function, the growth of lettuce plants grown in a plant factory was estimated continuously and automatically by use of a low-cost automatic plant growth monitoring system with a personal computer.