Effect of Short-period Air-conditioning during Night on Yield and Characteristic Form of Cut Roses in Summer

Abstract

The objective of this study was to investigate the effect of brief exposure to air-conditioning or the air-conditioning time zone in summer during the night on the cut flower yield and characteristic form of roses. The petal length and number of petals of Rosa ‘Applaudissements’ grown under four-hour air-conditioning at 18 or 21°C at EOD (end of the day) were greater than those without air-conditioning, although the days to flowering and number of cut flowers were the same. The characteristic forms of flowers that were air-conditioned at 24°C and non-air-conditioned plants were the same. The days to flowering and number of cut flowers in Rosa ‘MEIKATANA’ were the same when the 21°C air-conditioning was carried out all night and at either EOD or EON (end of the night) for four hours, respectively. Although the air-conditioning was carried at EOD, EON, or all night, the values for the dry matter and length of cut flowers were higher than those from cut flowers without air-conditioning. On comparing electric power consumption with all night air-conditioning, those of EOD and EON were 58 and 31%, respectively. These results show that the EOD and EON air-conditioning treatment at 21°C are efficient temperature control techniques compared to all night air-conditioning.