Protecting carnations from high summer temperatures

Publication date	February 28, 2020
Sector	Agriculture, Forestry, Fisheries
Region name	Kinki（Hyogo Prefecture）

Climate change impacts

Carnations grown in Hyōgo Prefecture account for the largest share of sales in the Kansai market and the flower is strongly identified with the prefecture. However, high summer temperatures are being reflected in a drop in the quality of flowers in the autumn.

Adaptation activity

Though heat pumps (commercial air conditioners) are increasingly being used for winter heating, the Hyogo Prefectural Technology Center for Agriculture, Forestry and Fisheries is investigating how to use them to improve autumn flower quality through nighttime cooling in the summer. Results showed that cooling at 21℃ for 4 hours after sunset in the summer months improved quality, and shortened the cultivation period between pinching and flowering (see Note).

The following conditions and benefits have been identified:

Autumn stems were more robust and better quality compared to those that had not been cooled, (Fig. 1).
Electricity consumption could be reduced by about 40% compared to cooling for the whole night (Fig 2).
The cultivation period necessary for producing cut flowers at the end of the year could be shortened by 14 days (Fig. 3).
Electricity per plant, including mandatory electricity charges, was calculated to be approximately ¥10. The timed cooling trials confirmed that commercial air conditioners could be successfully used in agricultural production (Fig. 4). Results at the test site showed that the application of timed rapid cooling after sunset in summer months at 21℃ requires a device that automatically opens and closes greenhouse windows with a timer in addition to the heat pump, or a four-stage thermostat that allows the temperature to be changed according to time, in order to prevent the indoor air temperature from going back up after cooling.

Outputs / Expected benefits

By implementing the cooling regime as described above, an 18% increase in the autumn crop of high-quality carnations has been estimated, with a projected 17% increase in end of year sales. This is expected to help maintain the brand identity of Hyogo Prefecture as the leading supplier of carnations for the Kansai market.
(This research was part of the Ministry of Agriculture, Forestry and Fisheries’ "Promotion of Scientific and Technological Research in Agriculture, Forestry and Fisheries and Food Industry" program)
Note: The cultivation period is considered to be the number of days required from pinching to flowering.

Fig. 1 Stem strength (angle of deviation when the stem is held horizontally) according to different production methods.
(Source: Awaji Institute of Agricultural Technology, Hyogo Prefectural Technology Center for Agriculture, Forestry and Fisheries, )

Fig. 2 Heat pump operating hours and in-facility temperatures.
(Source: Awaji Institute of Agricultural Technology, Hyogo Prefectural Technology Center for Agriculture, Forestry and Fisheries)

Fig.3 Number of days before flowering according to production method.
(Source: Awaji Institute of Agricultural Technology, Hyogo Prefectural Technology Center for Agriculture, Forestry and Fisheries)

Fig. 4 Field verification
(Source: Awaji Institute of Agricultural Technology, Hyogo Prefectural Technology Center for Agriculture, Forestry and Fisheries)

Source: Awaji Institute of Agricultural Technology, Hyogo Prefectural Technology Center for Agriculture, Forestry and Fisheries "Promotion of flowering and improvement of autumn quality by short-time air conditioning after summer sun sun in carnation"
http://hyogo-nourinsuisangc.jp/18-panel/pdf/h27/13.pdf; Website of the Hyogo Prefectural Technology Center for Agriculture, Forestry and Fisheries, "Flowering Promotion and Quality Improvement Technology by Summer Short-Time Night Cooling of Carnation"

Relevant information: "Global Warming and Agriculture, Forestry and Fisheries" by Agricultural Environment Change Research Center Global Warming Research Office, National Institute of Agriculture and Food Industry Technology (Agriculture and Research Institute)
https://www.naro.affrc.go.jp/org/niaes/ccaff/english/

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