Shinichi Kosaka

Potential Use of Mercury-Free Lamps in Plant Factories

Abstract We investigated the effects on plant growth of a mercury-free lamp with high CRI, operated on inductive ballast. This lamp has a spectral power distribution in the 600 to 780-nm region, higher than that of conventional lamps. Since this lamp is free of mercury, it is less harmful to the environment than lamps that contain mercury; therefore, we believed that this type of lamp would be useful in plant factories. We examined the effects of the mercury-free lamp on the growth characteristics of sunflower and lettuce plants, and compared them to plants grown under conventional lamps. We concluded that the mercury-free lamp advanced plant growth, increased leaf area, and inhibited leaf number compared to the conventional lamp, making it attractive for large-scale use in plant factories.

Efficient Culture Method of Pavlova Lutheri by Light Intensity Control

Abstract Using artificial lighting, productive cost is high, and reducing the cost is an important factor of cultivation. To reduce productive costs, an economical method of culturing micro-alga, Pavlova lutheri using light intensity control was considered. Minimum light supply to grow cell was calculated using the growth curve at 10,30,60 and 100% light intensity. When light intensity control was simulated, consumption energy of light was reduced about 40% of 100% light intensity. In The actual growth using light intensity control, consumption energy was reduced about 60% of 100%light intensity.

Plant growth control by regulated lighting conditions

In this study, both a mercury free lamp and a conventional lamp were used for growing lettuce, which means that the R/FR environment was changed for one plant growth interval between R/FR>3.0 and R/FR<1.0. From the experiments, the growth speed was faster and the leaf shape and leaf area were larger than growing the lettuce under a single lamp.

Experimental Studies of the Relation between Light Intensity and Cell Density of Mass Cultured Pavlova lutheir.

Producing large quantities of microalgae is one of the most limiting factors when developing large-scale culture techniques for shellfish. When artificial light is used for producing microalgae, it is one of the most expensive costs. In this study, we conducted experiments to determine the optimum light intensity and efficient culture protocol for microalga Pavlova lutheri using a 200-liter chamber.A 200-liter culture chamber was used to determine the average distribution of PPFD. Under two conditions : 1) filtered seawater (control), and2) filtered seawater with culture medium added and 1.0×107 cells·ml-1 P. luatheri. Average distribution of PPFD for the filtered sea water was 1, 800μmol·m-2·s-1 at irradiation of the full light intensity. But when P. lutheri was cultured in the chamber, available photosynthetic area was reduced to a half of the chamber.P. lutheri was cultured at irradiation of10%, 30%, 60%and full light intensity at 15°C and an aeration of 30l·min-1. Maximum cell density correlated positively to light intensity with full light regime supporting more than 2.0·107cells·ml-1.We conclude that if higher light intensity is used for the chamber, P. lutheri will obtain nigher cell densities. Additionally the control of light intensity is effective method to decrease the production cost of P. lutheri.