Effect of Duct-type Pad and Fan on Temperature Reduction andEustoma Quality
Flower Cultivation Course: Watanabe Yoji
(Instructor: Usuda Hiromichi)
1. Introduction
The average temperature in Japan has increased at a rate of approximately 1.2°C per
century since 1898. With the rise of the temperature, so-called “tropical nights” (nightswith a lowest nighttime temperature of 25°C or higher) and extremely hot days (days witha daily highest temperature of 35°C or higher) have increased, while winter days (dayswith a daily lowest temperature of less than 0°C) have decreased. (From the Japan
Meteorological Agency website)
There is a concern that high temperature will cause plant body temperatures to risedue to photosynthesis inhibition by intense light and heat from solar radiation, making it
impossible to maintain optimum growth temperatures. Therefore, it is necessary forhorticultural facilities to take measures against the heat in summer.
2. Purpose of Study
Currently, Pad and Fan (hereinafterreferred to as P&F), fine mist cooling, andcooling using heat pumps have been
introduced in facility horticulture as heatmeasures. However, the issue is that they
are expensive to install. Therefore, I focusedon duct-type P&Fs, which are inexpensive toproduce and can be homemade, andinvestigated their temperature reduction
effect. I also investigated the effect of ducttype P&F on the quality of Eustoma.
3. Method of Study(1)

ProductionofDuct-type

P&FandInvestigation of Temperature Reduction Effect
The duct-type P&F cools the plant population
by sending outdoor air cooled by moistenedpads through a fan into a duct. The production
cost was 79,436 yen.

Figure-1 Outline of Test Area

For the temperature reduction effect study, as shown in Figure-1, thermometers wereinstalled in the outdoor airspace, inside the P&F equipment, and in the test area (1), testarea (2), comparison area (1), and comparison area (2) on June 21, and temperaturetransitions were investigated. In addition, humidity in the outdoor air and inside the P&F
equipment was investigated, the reason being how much cool pads moistened with watercan raise the humidity inside the P&F equipment has a significant effect on the temperature
reduction effect.
(2) Investigation of the Effect on the Quality of Eustoma
Ten plants each of Mira Coral, Bolero Blue Flash, and Amber Double Mint shown in Fig.
4 were investigated for height, weight, and number of flowers at the time of harvest in thetest and comparison areas. Sown on January 27, planted on March 31, and harvested andstudied from July 4, starting from the second flower blooming.
4. Results and Observations(1) Temperature Reduction Effect of Duct-type P&F
Figure 2 shows the temperatureandhumidity

equipment

insideonatheP&Fsunny,high-temperature day on July 2. At 14:50,
when the outdoor temperature wasatitshighest,thetemperatureinside the P&Fequipment was

32.9°C

40.2°Cagainstintheoutdoor air, and the humidity was
27% in the outdoor air and 42%
inside the P&F equipment, resulting
in a -7.3°C temperature and +15%

Figure 2: Transition of Temperature and Humidity inside
the P&F Equipment on Sunny and Hot Days

humidity inside the P&F equipment.
The highest temperatures in the test and comparison areas (1) on July 2 were 40.3°C
and 42.5°C, respectively, with the test area at -2.2°C. The highest temperatures in the test
and comparison areas (2) on July 2 were 38.4°C and 41.2°C, respectively, with the testarea at -2.8°C, demonstrating the temperature reduction effect of the duct-type P&F system.
(2) Effect on the quality of Eustoma
In the grass height harvest survey, as shown in Figure 3, the overall average was 59.6
cm in the test area and 60.6 cm in the comparison area, 1.0 cm higher in the comparison
area. In the weight harvest survey, as shown in Figure 4, the overall average weight of thetest area was 58.9 g in the test area and 53.4 g in the comparison area, 5.5 g heavier thanthat of the comparison area. In the number of flowers harvest survey, as shown in Figure

5, the overall average was 0.7
higher in the test area than in thecomparison area, with an overall
average of 5.2 in the test areaand 4.5 in the comparison area.
The result was a 1.0 cm higher
grass height in the comparison
area, a 5.5 g heavier weight in theFigure-3 Harvest survey (Grass Height)

test area, and 0.7 more flowers inthe test area on average. The
reason for the shorter grass heightin the test area may be due to thestresscausedbythestrong

shaking of plants due to high wind
inthetestarea

duringP&Foftheseoperation.

Figure-4 Harvest Survey (Weight)(3) Future Issues
Asaresultinvestigations, the following threeissueswereidentified:(1)

improvement of the duct-type P&F
cooling efficiency, (2) review of theinstallation

timing,and(3)adjustment of the air volume. I

Figure-5 Harvest Survey (Number of Flowers)

would like to increase the coolingeffect of duct-type P&F by improving these issues, which will lead to the enhancement of
the quality of Eustoma.
*Following is a description of the figures and tables
図-１

試験区の概要＝Figure-1 Outline of Test Area

試験区＝Test Area
対照区＝Comparison Area
外気＝Outdoor Airspace
装置内＝Inside P & F Equipment
ダクト穴

24 個＝24 duct holes

ダクト穴30 個＝30 duct holes

ダクト穴

36 個＝36 duct holes

北：north南：south図-2

晴天高温日のＰ＆Ｆ装置内の温度と湿度の推移＝Figure 2: Transition ofTemperature and Humidity inside the P&F Equipment on Sunny and Hot Days
外気温度＝Outdoor Air Temperature
Ｐ＆Ｆ装置内温度＝Temperature inside P&F Equipment
外気湿度＝Outdoor Air Humidity
Ｐ＆Ｆ装置内湿度＝Humidity inside P&F Equipment
図-3

収穫調査（草丈）＝Figure-3 Harvest Survey (Grass Height)

図-4

収穫調査（重量）＝Figure-4 Harvest Survey (Weight)

図-5

収穫調査（輪数）＝Figure-5 Harvest Survey (Number of Flowers)

フルフルローズ
ミラコーラル

8 列＝Full Full Rose 8 Rows
14 列＝Mira Coral 14 Rows

ボレロブルーフラッシュ

10 列＝Bolero Blue Flash 10 Rows

ソワレピンクフラッシュ

9 列＝Soiree Pink Flash 9 Rows

キャンディマリン

8 列＝Candy Marine 8 Rows

アンバーダブルミント

8 列＝Amber Double Mint 8 Rows

ファンシーラベンダー

7 列＝Fancy Lavender 7 Rows

ニューリネーションイエロー

5 列＝New Lination Yellow 5 Rows