The effects of temperature and daylength on flower initiation and development in Dianthus allwoodii and Dianthus alpinus

In four experiments the major effect on flowering was that of temperature. Temperatures applied between 2 October and 20 February influenced the time of flowering of D. allwoodii, 'Doris', while in D. alpinus, 'Pike's Pink', temperatures applied over a longer period between 2 October and 11 March in fluenced the time of flowering. Keeping stock plants at low temperatures, b efore cuttings were taken, advanced flowering. The earliest flowering in 'D oris' was achieved by storing stock plants at 3.9 degrees C and then rootin g cuttings at 14.9 degrees C (rather than at 10.0 degrees C) suggesting tha t it was possible to satisfy their flower induction requirement entirely du ring cold storage. In 'Pike's Pink' earliest flowering was achieved by stor ing stock plants at 3.9 degrees C and then rooting cuttings at 10.0 degrees C, suggesting that the cold requirement for flower induction was not entir ely satisfied by cold storing stock plants but in addition needed some time at low temperature during rooting. The cold requirement of 'Pike's Pink' w as greater than that of 'Doris' and in several treatments was not satisfied sufficiently for flowering to occur. The number of flowers in 'Doris' was increased by low stock plant temperatu res, low temperatures post-rooting, and higher temperatures during growing on. In 'Pike's Pink' number of flowers were increased by low stock plant te mperatures and low temperatures post-rooting. (C) 2000 Elsevier Science B.V . All rights reserved.