Abstract
Roots and leaves of freesia corms in forcing culture must be developed even during low temperature treatment. It is also difficult to plant them since their roots and leaves have already become long after the cold treatment. Therefore, skill in the management is required. This study was carried out to find the effect of spot cooling on the forcing culture by using a spot air-conditioner instead of low temperature treatment of the corms. Corms of freesia ‘Rijnveld's Golden Yellow’ of which the dormancy had been broken by high temperature storage at 30°C and ethylene application were used. They were stored under moist condition at 9°C for 0, 4 or 6 weeks, or at 9°C for 6 weeks and then 15°C for 2 weeks on 11 August. After the temperature treatment they were planted on two soil beds (9.4m×0.7m each) in a green-house. One was a spot cooling bed with the spot air-conditioner and the other was a control bed without air-conditioner. The spot cooling bed was covered with tunnel-shaped sheet 30 cm in height to insulate the bed, and cool air was channeled into the tunnel. The spot cooling continued until 5 October when the mean air temperature in the greenhouse went below 20°C. The air temperature on the spot cooling bed was maintained about 4-7°C lower than that on the control bed. Corms which received spot cooling from 11 August for 8 weeks without 9°C treatment flowered on 13 December and the quality for cut flowers was improved. The use of the spot air-conditioner made it possible to reduce the troublesome work concerned with low temperature treatment and planting as mentioned above. For these reasons, spot cooling was proved to be effective in forcing culture of freesia.
