Abstract: The process of floral bud differentiation, growth and floral development of Chrysanthemum morifolium Ramat1‘J inba’with different photoperiod treatments were studied in this experiment. The results
showed that the inflorescence differentiates from the ap ical growing point, the whole p rocess could be divided
into nine stages: the vegetative growing stage, initiative stage of floral bud differentiation, the initial and final
stage of involucre p rimordia differentiation, the initial and final stage of floret primordia differentiation and the
initial, metaphase and final stage of crown formation. The order of inflorescence differentiation is centripetal,
i1e1, from the outside to the inside. The differentiation of stamen and gynoecium accompanied that of floret
crown. It took 23 days in the whole bud differentiation, the inflorescence p rimordia differentiation took more
days than that of floret. Bud differentiation of p lants under short day treatmentwere uniform and normal. However, those under short2long day treatments differed in individuals, delayed flowering and abnormal flowers
were observed. Plants under long day treatment failed to bloom.

Key words: Chrysanthemum, Photoperiod, Floral bud differentiation, Growth, Flowering