Ecological Modelling 352 (2017) 128–138 Contents lists available at ScienceDirect Ecological Modelling j ourna l h omepa ge: www.elsevier.com/locate/ecolmodel Temperature-dependent regulation of induction into secondary dormancy of Polygonum aviculare L. seeds: A quantitative analysis Cristian Malavert a,b,∗ , Diego Batlla a,c , Roberto L. Benech-Arnold a,b a IFEVA, Facultad de Agronomía, Universidad de Buenos Aires, CONICET, Av. San Martín 4453, Ciudad de Buenos Aires C1417DSE, Argentina b Universidad de Buenos Aires, Facultad de Agronomía, Departamento Producción Vegetal, Cátedra de Cultivos Industriales, Av. San Martín 4453, Ciudad de Buenos Aires C1417DSE, Argentina c Universidad de Buenos Aires, Facultad de Agronomía, Departamento Producción Vegetal, Cátedra de Cerealicultura, Av. San Martín 4453, Ciudad de Buenos Aires C1417DSE, Argentina a r t i c l e i n f o Article history: Received 27 July 2016 Received in revised form 22 February 2017 Accepted 9 March 2017 Keywords: Germination Polygonum aviculare Secondary dormancy Temperature Thermal time a b s t r a c t In seeds of many summer annuals low temperatures under moist conditions provoke dormancy release while high temperatures induce secondary dormancy. Seed dormancy level establishes the range of temperatures under which germination is possible. The range of temperatures permissive for seed ger- mination is determined by two threshold limit temperatures: Lower limit temperature (T l ) and High limit temperature (T h ). Numerous studies have been conducted to characterize the effect of temperature on dormancy release, but there is very few information on how temperature regulates secondary dormancy induction. Seeds of Polygonum aviculare were stratified at 1.6, 5 and 10 ◦ C until achieving a minimum dormancy, and then were induced into secondary dormancy by further storage at 10, 15, 20, 25 and 30 ◦ C. Based on obtained germination time course-curves we quantified changes in the thermal range permissive for seed germination through variations in the mean lower limit temperature for seed germi- nation (T l(50) ) using a mathematical simulation germination model. Our data suggest that induction into secondary dormancy in P. aviculare seeds can be assessed quantitatively through changes in T l(50). This changes could be described through a Dormancy Induction Thermal-Time Index (DI tt ), in which thermal time units are accumulated above a threshold temperature from which secondary dormancy is induced (7.9 ◦ C). Additionally, the induction-rate into secondary dormancy was affected by the stratification tem- perature during dormancy release. We conclude that the effect of temperature on the rate of dormancy induction is not only dependent on prevailing temperature, but also on temperature experienced by seeds during previous dormancy release and the resulting dormancy status of the seed population. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Seed dormancy has been defined as “an internal condition of the seed that impedes its germination under otherwise adequate hydric, thermal and gaseous conditions” (Benech-Arnold et al., 2000). Depending on the timing of occurrence, dormancy is classi- fied in primary and secondary dormancy (Karssen, 1982). Primary dormancy refers to the innate condition presented by the seeds when they are dispersed from the mother plant (Bewley and Black, 1994). Secondary dormancy refers to a dormant state that is induced in non-dormant seeds, or re-induced in once-dormant seeds after a sufficiently low dormancy had been attained (Hilhorst, ∗ Corresponding author at: IFEVA, Facultad de Agronomía, Universidad de Buenos Aires, CONICET, Av. San Martín 4453, Ciudad de Buenos Aires C1417DSE, Argentina. E-mail address: malavert@agro.uba.ar (C. Malavert). 1995, 1998). Polygonum aviculare L. (Knotgrass, yard knotweed) belongs to the Polygonaceae family and is a cosmopolitan common summer annual herbaceous weed of temperate climates (Holm et al., 1997). Under natural conditions, P. aviculare seeds tend to form persistent seed-banks in the soil and show cyclic changes in dormancy status according to the predominant season (Courtney, 1968; Baskin and Baskin, 1985, 1990; Forcella et al., 2000). P. aviculare seeds usually display a high dormancy level (primary dor- mancy) at the moment of dispersal which normally takes place at the end of the summer (Kruk and Benech-Arnold, 1998; Batlla and Benech-Arnold, 2003). This high dormancy level is evidenced by the fact that germination does not occur at any temperature in recently dispersed seeds (Batlla and Benech-Arnold, 2003). The seeds are released from dormancy if moistened, through the exposition to low temperatures (stratification); these conditions normally pre- vail in the soil during the months following dispersal (i.e. autumn and winter), thus determining a minimum dormancy level at the http://dx.doi.org/10.1016/j.ecolmodel.2017.03.008 0304-3800/© 2017 Elsevier B.V. All rights reserved.