Local Heating of Crown Increases Emergence and Elongation of Gerbera Flower

In this study, we found that local heating of the crown (rhizome) of gerbera (Gerbera jamesonii Bol. ex Adlam.), which includes the apical meristem, promotes flower stem emergence and elongation. We conducted local heating experiments over two winters on nursery plants that were set during the previous summer, using different varieties of gerbera in each season: ‘Banana’ and ‘Kimsey’ in winter 2013–2014, and ‘Kimsey’ in winter 2014–2015. We heated one or both sides of the crown of each plant by placing it in contact with a hot water flow tube (water temperature = 33°C) or stainless-steel heater tape. This local heating advanced the harvest time of cut flowers, and increased the total number of cut flowers harvested and the number of cut flowers of 40 cm or more, particularly in ‘Kimsey’. These local heating effects were particularly notable when the average temperature of the crown was kept high and the room temperature was low. Local heating increased or had no effect on the total cut flower weight per plant. However, the individual cut flower weight and capitulum diameter were smaller with local heating of the crown. The application of this local heating technology to gerbera is expected to reduce heating costs and help control the harvest time.