High temperatures applied at fall forcing disturb ovule development in Syringa vulgaris L. “Mme Florent Stepman”

Abstract

Under natural conditions, Syringa vulgaris blooms in May but it may be forced to produce blooming panicles in autumn, winter and early spring. To break winter dormancy, plants require high temperatures, the range of which depends on the forcing date. Forcing in November requires exposure to temperatures of *37°C. Such an exposure may affect the development of both male and female flower organs. In this work we have followed the anatomical changes in the ovule development in buds collected from plants forced in autumn, and compared them to those in plants blooming under natural conditions in May. From the earliest identifiable stages, in flowers forced in November the ovule development was delayed relative to the normal development pattern. Ultimately, most of the ovules (83%) degenerated before the differentiation of the embryo sacs was completed. We believe that it is the high temperatures required during autumn forcing that affect the development of female gametophytes, leading to the formation of defective structures which often degenerate. This in turn may reduce the esthetic appeal of the inflorescences and reduce their commercial value.

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

“…Lilac inflorescences on a shrub can last up 3 weeks, but the longevity of cut branches is greatly reduced (Skolimowska et al 2011), especially so on flowers produced by forcing. Studies on quality of lilac panicles as affected by the forcing date (Jedrzejuk and Szlachetka 2005;Jędr-zejuk 2005;Jędrzejuk and Łukaszewska 2008) showed that the poorest quality of lilac inflorescences was in November when deep shrub dormancy must be overcome by temperatures reaching 35-37°C. Petals from inflorescences forced in November had much larger intercellular spaces than petals forced in spring or blooming naturally outdoors in May (Jędrzejuk and Łukaszewska 2008).…”

“…Studies on quality of lilac panicles as affected by the forcing date (Jedrzejuk and Szlachetka 2005;Jędr-zejuk 2005;Jędrzejuk and Łukaszewska 2008) showed that the poorest quality of lilac inflorescences was in November when deep shrub dormancy must be overcome by temperatures reaching 35-37°C. Petals from inflorescences forced in November had much larger intercellular spaces than petals forced in spring or blooming naturally outdoors in May (Jędrzejuk and Łukaszewska 2008). In this study, lilac inflorescences blooming on shrubs forced in November had longevity reduced by 5 days (over 20 %) relative to lilacs blooming in their natural period in May.…”

“…This last aspect needs detailed studies in forced lilacs. High forcing temperatures probably affect a hormonal balance in lilac flowers, as can be deduced from the degenerative changes taking place in the generative structures of flowers from the early forcing dates (Jędrzejuk 2005;Jędrzejuk and Łukaszewska 2008) and such hormonal changes due to forcing procedures possibly hasten flower senescence after harvest. The successive studies on lilac flower senescence should include analyses of endogenous hormones, combined with a closer control of the thermal conditions during the forcing procedure.…”

Shade Ameliorates High Temperature-induced Inhibition of Growth in Herbaceous Peony (Paeonia lactiflora)

“…In addition, heat shock protein genes (HSP) are certified to significantly increase the heat resistance of the plants (Zou et al, 2012). And in the ornamental plants, the studies about the influence of heat stress on plant growth and its response have also been performed, such as lilac (Syringa vulgaris) (Jedrzejuk and Lukaszewska, 2008), chrysanthemum (Dendranthema grandiflora) (Janka et al, 2013).…”

Polyvariance of Floral Organogenesis of Syringa josikaea Jacq. (Oleaceae) in the Conditions of the Arctic Urbanized Territory

“…Information on the floral organogenesis and cytoembryology of species and cultivars of lilacs in the scientific literature is rather limited [4], [12], [13], [21], [34], the phenology of their flowering is studied much better [1], [2], [6], [23], [30], [31]. In recent years active research has begun on reproductive development of the most promising cultivars of S. vulgaris [12], [13], [21], similar studies on S. josikaea are few [18], [22], [29]. However, it is the S. josikaea, that has been successfully introduced in the urbanized territories of the Euro-Arctic region, while S. vulgaris does not form reproductive organs in the conditions of the polar day and does not bloom.…”