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The growth and yield of tomatoes in greenhouses covered by heat insulation film were investigated in Ishigaki, a subtropical area of Japan with high temperature and high solar radiation. High-density planting of tomatoes was carried out in June, July, August, October, and November, with a low node-order pinching system. The plants were grown in two greenhouses, one covered by a thermal barrier film (TBF) for heat insulation and the other covered by a polyolefin film (PO). Under TBF, the maximum temperature was up to 3.6°C lower than that under PO, and the mean temperature was 0.4°C lower. The leaf area index (LAI) of the June planting was 3.0 under TBF and 3.4 under PO, significantly lower than the LAIs of the other plantings, which ranged from 3.9 to 5.4. The specific leaf area (SLA) varied with the cultivation season, with that under TBF and PO being highest in November plantings grown in winter. SLA under TBF was higher than that under PO in the same cultivation seasons. The amount of total aboveground dry matter was significantly lower in the June planting under TBF and showed no difference in other plantings. Distribution to fruit was higher under TBF than under PO, especially in summer cultivation. The yields under TBF were significantly higher than those under PO in the July planting, and the yields under PO were significantly higher in the November planting. Under TBF, the rate of fruit cracking was reduced in the June, July, and August plantings. Under TBF and PO, plantings in October and November produced puffy fruits. The light use efficiency under TBF was higher than that under PO in the same cultivation seasons, apart from the June planting. Tomato cultivation under TBF reduced the damage from intense solar radiation during summer. TBF enabled penetration of sufficient solar radiation to distribute photosynthates to each part of the plant because of a limited sink and abundant solar radiation in a subtropical summer. These results indicate that TBF and sink-limited cultivation are effective systems for use in the high temperature and high solar radiation environments of tropical and subtropical regions. Key Words: leaf area index (LAI), light use efficiency (LUE), low node-order pinching and high-density planting, partition rate, plant factory.

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Tomato 'CF momotaro yoku' was sown 6 times in 2014 and 2015 to investigate the relationship between the emergence date and flowering date of the first truss of tomato with low node-order pinching and high-density planting. When tomato was sown in April, June, August and September, the time from emergence to flowering (DEF) was 36.4~39.6 days. When tomato was sown in December, DEF was 49.8~62.0 days, being significantly extended. The emergence rate at 4 or 5 days after sowing (DAS) was negatively related to the periods between the flowering day of the first and last plant (r = -0.88). The emergence rate at 3 DAS was affected by the volume of irrigated water: the rate was 82.3, 72.9, 59.4, and 29.2% when irrigated with 3, 6, 9, and 16 mL/cell of water, respectively. Moreover, matric priming shortened the time required for an emergence rate of 80% by approx. 24 h, and for a flowering rate of 80% by approx. 5 days compared with the control without priming. For these reasons, the emergence rate until 4 or 5 DAS was important for the simultaneity of flowering, especially in winter cropping. The water content of the medium affected the emergence rate. Matric priming improves the simultaneity of both emergence and flowering.

For effective CO 2 enrichment in protected horticulture, it is necessary to understand the distribution of the CO 2 concentration in a greenhouse. In this study, we used sodium hydroxide (NaOH) aqueous solution, whose pH decreases when it absorbs CO 2 to estimate the CO 2 concentration in a greenhouse. When plastic boxes with containing NaOH solutions were placed in various CO 2 concentration environments, there was a positive correlation between the CO 2 concentration and reduction the pH. Further, the pH was affected by the surface area and temperature of the aqueous solution, NaOH concentration, and CO 2 absorbing treatment time. We considered that using a hard plastic box with 50 mL of 0.004 mol・L -1 NaOH solution was suitable for measuring the pH in the greenhouse. We examined the associations among the CO 2 concentration, solution temperature, and pH in different environments using a growth chamber, and we formulated relational expressions. About 100 plastic boxes with 50 mL of 0.004 mol・L -1 NaOH solution were placed for 3 hours in a greenhouse with a CO 2 enrichment tube that was set for medium planted strawberry plants. pH changes differed depending on the location. The estimated CO 2 concentration was higher in the greenhouse than outside, and varied depending on the distance from the CO 2 enrichment tube and height from the ground in the greenhouse. The estimated CO 2 concentrations were about 100 ppm higher than the measured CO 2 concentrations, possibly affected by light and wind. We propose that using NaOH solution is a simple and effective method to estimate the distribution of the CO 2 concentration in a greenhouse. Key Words：CO