Taiwanese montane Sambucus chinensis seeds require warm stratification, contrasting with other congeneric temperate members. Issue 3 (22nd May 2014) - Chen, Shun-Ying
Abstract: Many temperate plant genera, like Sambucus, have species with range disjunctions among North America, Europe and/or Asia. Cold stratification (sometimes in combination with warm stratification) is the primary mechanism to break seed dormancy in these species. For some of these genera showing Northern Hemispheric disjunctions, members also occur in subtropical or tropical regions, mostly confined to higher elevations where climate and vegetation differ from those in northern latitudes. We made two hypotheses concerning germination for the subtropical Taiwanese Sambucus chinensis : (1) seeds from populations exposed to warm temperatures would require warm stratification, and (2) seeds from populations exposed to cold temperatures need cold stratification. We investigated the germination (including embryo growth) of non-stratified seeds over a range of temperatures and tested the effects of cold stratification and of gibberellins GA3 and GA4 on germination. The amount and timing of germination among populations varied substantially in response to temperature treatments. Seeds from all populations of this species required warm temperatures for dormancy break and germination, regardless of environmental conditions. As such, the majority of seeds had non-deep simple morphophysiological dormancy, which, until now, has not been reported in any members of Sambucus . The seed characteristics of the subtropical S. chinensis are different from those of temperate members of the genus in which cold stratification is the predominate treatment to overcome dormancy.