Comparison of petal senescence in forced and unforced common lilac flowers during their postharvest life

Recently, the programmed cell death (PCD) is studied in the context of the postharvest longevity of cut flowers with the goal of slowing down the processes that ultimately lead to flower death, and to ensure a long display life of cut plant material. In this study, the phenomenon of PCD in petals of common lilac (Syringa vulgaris L.) was observed, aimed to compare degradation of petal cells in flowers blooming under natural conditions with those forced in November. For the early lilac forcing, a deep dormancy has to be broken by high temperatures 35-37 A degrees C negatively affecting postharvest life of cut branches. The trials included as well the observation of the effect of two flower preservatives on the PCD in order to see if the prolongation of the lilac vase life was associated with a delay in the onset of the PCD symptoms. The vase life of cut lilacs was significantly increased by both preservatives. The first symptoms of PCD were evident in the flower bud stage. In petals from forced shrubs, the first symptoms of cell degradation were much more advanced than in lilacs blooming naturally in May. In forced flowers held in the preservatives, the degradative changes in cells occurred later than in those kept in water, but they were accelerated relative to a flower developmental stage.