Contents lists available at ScienceDirect Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet Seed responses to temperature indicate different germination strategies among Festuca pallescens populations from semi-arid environments in North Patagonia Aldana S. López a, ⁎ , Paula Marchelli a , Diego Batlla b , Dardo R. López c , María V. Arana a a IFAB (Instituto de Investigaciones Forestales y Agropecuarias Bariloche, INTA EEA Bariloche-CONICET), Modesta Victoria 4450, 8400, Río Negro, Argentina b IFEVA/Catedra de Cerealicultura, Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453, C1417DSE Buenos Aires, Argentina c INTA, EF Villa Dolores, Córdoba, Argentina ARTICLE INFO Keywords: North Patagonian rangelands Arid and semiarid environments Temperature Festuca pallescens Germination Thermal time model ABSTRACT Seed germination is one of the earliest phenotypes expressed by plants, and the accuracy to germinate in the correct time and place is essential for plant population fitness. Cues that regulate germination have been ex- haustively characterized in laboratory experiments. However, the way in which seed populations respond to these cues and the ecological meanings of this phenomenon are scarcely known. To help filling this gap, we studied the thermic regulation of seed germination and its link with local climatic characteristics in Festuca pallescens populations, an iconic perennial grass species of Patagonia. By coupling thermal time models with field and environmental data, we evaluated seed responsiveness to temperature during germination of nine Festuca pallescens populations distributed across their complete longitudinal range in North Patagonia. The idea behind this experimental design was to search for inter-population differences in early life traits relevant for recruitment of the species, and associate seed traits with local environmental characteristics. F. pallescens populations showed strong differences in seed sensitivity to temperature for the thermal regulation of the germination rate, described by the population mean thermal time for germination (θ (50) ) and its standard deviation (σ θ ). The greatest values of θ (50) and σ θ corresponded to populations inhabiting harsh environments. Moreover, θ (50) of the different populations showed strong correlations with their local thermal environmental parameters, indicating a relation between seed physiological traits and climate across the longitudinal gradient. We did not observe inter-po- pulation differences in the minimum temperature that allows germination (Tb = -0.47 ± 0.19 °C). Higher θ (50) and σ θ in populations from harsh climates may constitute a strategy of the species to increase fitness in hostile habitats, preventing anticipated germination and promoting a slower seed bank depletion in regions where establishment is highly limited. 1. Introduction Desertification is affecting arid, semi-arid and dry-sub humid re- gions all over the world mainly due to climatic variation and human activities (Reynolds et al., 2007; Stringer et al., 2017). Many of these ecosystems are dominated by perennial grasses with low capacity to overcome rapid environmental changes (Dukes et al., 2005), due to their reproductive system (seed obligated, seasonal seed banks, atte- nuated dispersal patterns) and grassing pressure (O´Connor, 1991). The potential of grassland species to adapt to climate change relies in part on their regeneration success and, therefore, is based on the ability to produce viable seeds and to cope with environmental stresses during germination (Donohue et al., 2010). Even though many species have vegetative propagation, adaptability depends on genetic diversity and therefore on sexual reproduction. In addition, germination of these dry rangelands species is erratic or episodic (O´Connor, 1991; Rotundo et al., 2015). Therefore, understanding germination in relation to en- vironmental conditions can help predicting adaptation. Germination is a critical process in the life cycle of plants that in- volves drastic changes such as the transition from a protected quiescent stage – the seed- to a stage of active growth, highly susceptible to the environment –the seedling- (Donohue et al., 2010). Being highly regulated and influenced by the environment, germination constitutes a stage that is under strong selection pressure (Pendleton and Meyer, 2004; Donohue et al., 2005). Differences in the germination behavior of numerous species is associated with the habitat suggesting the existence https://doi.org/10.1016/j.agrformet.2019.04.002 Received 2 December 2018; Received in revised form 1 April 2019; Accepted 4 April 2019 ⁎ Corresponding author at: IFAB (INTA EEA Bariloche-CONICET), Modesta Victoria 4450, 8400 Bariloche, Río Negro, Argentina. E-mail addresses: lopez.aldana@inta.gob.ar, anushlop@gmail.com (A.S. López). Agricultural and Forest Meteorology 272–273 (2019) 81–90 0168-1923/ © 2019 Elsevier B.V. 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