Germination responses to GA 3 and short-time chilling of three endemic species: Tripleurospermum pichleri, Cirsium leucopsis and Senecio olympicus (Asteraceae) SERAP KIRMIZI,* GÜRCAN GÜLERYÜZ† and HÜLYA ARSLAN† *Gemlik Asım Kocabıyık Graduate Vocational School, Horticulture Programme, Uludag ˘ University, 16600, Gemlik/Bursa, Turkey and †Faculty of Science and Arts, Department of Biology, Uludag ˘ University, 16059, Görükle/Bursa, Turkey Abstract In the present study, the germination characteristics of three endemic species from Turkey, Tripleurospermum pichleri (Boiss.) Bornm., Cirsium leucopsis D.C and Senecio olympicus Boiss. (Asteraceae), were investigated. Germination was studied for fresh seeds, for seeds subjected to short-time chilling (15 days, moist +4°C), to GA3 (100, 150 and 250 ppm) and a combination of chilling and GA3; in all cases seeds were incubated either at 20/10°C day/night with light daytime or at 20°C in darkness with daily short-time dim light (DSDL). In C. leucopsis seeds, all GA3 treatments enhanced the final germination percentages. The mean germination time (MGT) of C. leucopsis was lower under DSDL than with photoperiod. The chilling treatment with GA3 in DSDL significantly increased germination in S. olympicus seeds (from 45 to 87%). Germination increased to 55% in T. pichleri by chilling under photoperiod compared with 32% by chilling followed by DSDL. In conclusion, these three co-existing endemic Asteraceae species have different germination behaviours; something that should be taken into account for ex situ propa- gation. However, an efficient way to germinate all species is to use 250 ppm GA3 and 20/10°C with photoperiod. Keywords: alpine plants, Cirsium leucopsis, ex situ propagation, seed dormancy, Senecio olympicus, Tripleurospermum pichleri. Received 9 December 2009; accepted 28 August 2010 Introduction Seed germination is a phase in the reproductive cycle that is of determining importance to the reproductive success of plants (Bu et al. 2008). Environmental conditions in alpine areas can change sharply within a local area, reflecting microtopographic differences in a snow- melting regime (Billings & Bliss 1959; Miller 1982; Onipchenko et al. 1988; Körner 1999). Alpine and arctic regions have high levels of endemic species, probably because of harsh habitat characteristics (Väre et al. 2003). Alpine plants show great variability in germination behaviour, which has sometimes been attributed to envi- ronmental conditions, but is not always associated with habitat characteristics (Bliss 1971; Urbanska & Schütz 1986; Chambers 1989). The timing of germination in alpine habitats, where the growing season is very short, plays a critical role. A dormant seed is one that does not have the capacity to germinate in a specified period of time under any combi- nation of normal physical environmental factors that is otherwise favourable for its germination (Baskin & Baskin 2004). Germination requirements have evolved differently across species for adaptation to the prevailing environ- ment so that germination occurs when conditions are likely to be suitable for a new generation (Finch-Savage & Leubner-Metzger, 2006). Dormancy patterns are often similar for closely related taxa (Karlsson & Milberg 2007), but can substantially differ within a family, even among co-occurring species (Karlsson et al. 2008). Chilling is regarded to be the most important way to break dormancy in seeds of summer annuals and most temperate perennials (Baskin & Baskin 1998). Light and Correspondence: Serap Kırmızı Email: skirmizi@uludag.edu.tr Plant Species Biology (2011) 26, 51–57 doi: 10.1111/j.1442-1984.2010.00302.x © 2010 The Authors Journal compilation © 2010 The Society for the Study of Species Biology