This paper introduces the Plant Factory R&D Center, Chiba University supported by the Ministry of Economy, Trade and Industry (METI) and the plant factory project at Kashiwanoha campus supported by the Ministry of Agriculture, Forestry and Fisheries (MAFF).

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Artificial climate experiments were conducted to investigate the main cause that the petals with low coloring ratio appeared in Eustoma grandiflorum picotee cultivar. The influence of high temperatures during the day and night on petal coloration rates was examined using six artificial climate chambers to replicate day and night temperatures of 25 and 15°C, 25 and 20°C, 30 and 15°C, 30 and 20°C, 30 and 25°C, and 35 and 20°C, from the vegetative stage to the harvest. Petals with a color ratio of >40% to the whole petal area appeared at day and night temperatures of 25°C and of 15°C or 20°C, respectively, which were also suitable for growth. The color ratio of the petals at a daytime temperature of 30°C fell when nighttime temperatures were above 20°C. The ratio of petals with <5% color relative to the whole petal area was 85% and no colored petals appeared slightly at daytime/nighttime temperatures of 30°C and 25°C, respectively. Moreover at daytime/nighttime temperatures of 35°C and 20°C, respectively, the ratio of colored petals to the total petal area was <30% and almost all of the colored petals had a color ratio of 5% to 20%. And other features of cut flowers such as cut flower length, stem length and number of flower buds were also fine.

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The present study examined the effect of CO₂ enrichment on the growth and yield of tomato plants cultivated in a large-scale greenhouse with a high- ventilation rate. In this study, CO₂ enrichment referred to maintaining the CO₂ concentration inside the greenhouse at the same level as the atmospheric CO₂ level. Tomato plants (Solanum lycopersicum L.) were cultivated under 2 different CO₂ conditions —one group of plants was cultivated under CO₂ enrichment, and the other was cultivated under CO₂ non-enrichment— during the spring-summer and summer-autumn periods. In the spring-summer crop, leaf dry weight and leaf area of the tomato plants cultivated under CO₂ enrichment were greater than those of the tomato plants cultivated under CO₂ non-enrichment. In both the spring-summer and the summer-autumn crops, the total fruit yield per plant increased because of CO₂ enrichment. In the spring-summer crop, CO₂ enrichment led to increase in both the total fruit yield and the normal fruit yield. However, in the summer-autumn crop, the total fruit yield increased and the ratio of the normal fruit yield to the total fruit yield decreased because of CO₂ enrichment. These results reveal that CO₂ enrichment might increase the incidence of fruit malformation according to the cropping season. The effect of CO₂ enrichment on the fruit yield was influenced by differences in the environmental conditions during the cultivation periods. In conclusion, it is therefore necessary to assess whether the environmental conditions inside the greenhouse are suitable for plant growth under CO₂ enrichment.

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Efficient conditions for plant regeneration using adventitious buds differentiated from Atropa belladonna L. hairy roots under shaking culture were investigated. In the combination of relative strength of MS medium and various sucrose concentrations in liquid medium (hormone free), shoot formation was promoted at 5 and 10 g L^-1 sucrose. Root formation was stimulated at 30 g L^-1 sucrose, while shoot formation was inhibited. The total fresh weight increased with increasing the strength of MS medium but decreased strongly at doublestrength MS medium containing 90 g L^-1 sucrose. Multiple shoots with roots were obtained most efficiently from adventitious buds for one month of culture under normal-strength MS medium with 30 g L^-1 sucrose. These results suggest the possibility of mass propagation of shoots and application to the production of young plants from propagated shoots.

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