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Photoperiodic Responses of Garden Chrysanthemum June 1997.pdf




The objective was tostudy the flowering response of garden cultivars of Dendranthemum xgrandiflorum (Ramat.) Kitamura to temperature and photope riod. Fifteen garden mum cultivars were grown in ten temperature (18 and 24°C constant day and night greenhouse temperatures) and photoperiod (8,10,12,14, and 16h) combinations. Rooted cuttings were pinched above the fifth node and placed in thetemperature/photoperiod treatments. When axillaryshootsdeveloped, all but one shoot was removed to produce asingle stemmed plant. Photoperiods were provided by delivering 8hsunlight, then pulling black cloth and providing daylength extension with incandescent bulbs. Days to visible bud, days to first bud color, days to flower, node number, and stem length were measured. By 11 weeks after the start of photoperiod treatments, no difference was measured in days to flower in the 8-, 10-, and 12-h photoperiods at18°C. Days to flower increased as photoperiod increased from 12to14h.At 18°C, five cultivars flowered inthe 16-h photoperiod, while 10cultivars developed crown buds, i.e., flower buds that initi ated but had not developed. At 24°C, there was no difference in days to flower in the 8-and 10-h photoperiod, while days to flower increased as photoperiod increased from 10-to12-htreatment. Cultivars formed crown buds buthadnotreached flow ering in the 14- and 16-h photoperiods at 24°C. Regardless of temperature, stem length increased asphotoperiod increased above 10h

Keywords: Photoperiod Stem length crown buds

Libraries: Floriculture

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