Effects of photoperiod on growth and flowering of Chrysanthemum morifolium Ramat cv. Reagan Sunny

Chrysanthemum morifolium plants cv. Reagan Sunny were exposed to different photoperiods at two stages of flowering namely flower bud initiation and flower bud development. The photoperiods tested were natural photoperiod (control), 8 h daylight with 4 h incandescent (12PP), 8 h daylight with 2 h incandescent (lOPP), and 8 h daylight (8PP). The growth, time of different stages of flowering and flower quality were recorded. The growth was not obviously influenced by photoperiod at both stages of exposure. Flower initiation was promoted by 8 h photoperiod and delayed by incandescent light at the end of 8 h daylight. Buds formed under treatment with 4 h incandescent were not able to developinto flowers. Further bud development and the overall time of flowering were also delayed with 8 h photoperiod. Exposing plants to photoperiods during bud development delayed bud development, and also flowering if given 4 h incandescent. Despite delaying flowering, the 2 h incandescent at the end of8 h daylight period caused synchronization of flowering within a plant. Flower quality also did not obviously improve by shortening photoperiod.