696 PB 280 REDUCED WATER SUPPLY AFFECTS FALL ACCLIMATION OF EVERGREEN AZALEAS

Abstract

Three cultivars of evergreen azaleas, `Coral Bell', `Hinodegiri', and `Red Ruffle', were grown under four watering regimes in containers and placed outdoors or in the greenhouse. The water content of the growing medium was maintained at either 0.3 to 0.4 or 0.5 to 0.6 m3m-3 from June 16 to August 30, when half of the plants under each of these regime was switched to the other watering regime. Freeze tests were conducted on August 30 and October 9, 1993. Injury to leaves, lower, middle, and upper stems was evaluated visually. Acclimation of leaves and upper stems prior to the August test, in most cases, was not stimulated by reduced water content, while the response of lower and middle stems was cultivar and location specific. The lower water content treatment after August 30 generally increased freeze tolerance of all plant parts regardless of the previous watering regime. The higher water content treatment after August 30 either prevented or delayed acclimation.