Environmental signals for seed germination reflect habitat adaptations in four temperate Caryophyllaceae

Abstract

Summary 1.Requirements for dormancy break and seed germination are specific for all species and depend chiefly on phylogeny, geographical distribution, habitat preference and life cycle. Studying germination requirements of closely related species with a similar geographic distribution allows one to attribute variation in germination requirements to differences in habitat preference between the species. 2. We investigated requirements for dormancy break and the effect of environmental signals on induction of germination in seeds of four closely related Caryophyllaceae species growing in a variety of habitats ( Moehringia trinervia , Stellaria holostea , S. nemorum and S. graminea ). The species studied depend on disturbances in the vegetation for seed germination and subsequent seedling establishment. 3.Seedlings of all four species emerged both in summer and spring. Stellaria nemorum and M. trinervia , both growing in temperate forests, emerged mainly in summer under a closed forest canopy. Seeds of S. graminea , occurring in grasslands, did germinate in summer at an open site, but could not germinate under a closed forest canopy. Seedlings of S. holostea were observed in late summer when buried at an open site or in early spring when sown in a forest patch. 4. Seeds of S. holostea and M. trinervia were completely dormant at dispersal in early summer, while germination was low in fresh seeds of S. graminea and S. nemorum . Dormancy was broken, to a certain extent, during all three after-ripening treatments applied (dry storage, cold and warm stratification). 5. The effect of three gap-detection signals (light, fluctuating temperatures, nitrates) on germination of fresh and dry stored seeds was tested. Seeds of S. holostea only germinated in response to daily fluctuating temperatures. Although light was the most important signal affecting germination of S. graminea and M. trinervia , we also observed a positive effect of fluctuating temperatures and nitrates on germination. The effect of fluctuating temperatures on germination of S. nemorum was small in both light and dark incubated seeds. Seed germination in this species generally occurred in response to addition of light and nitrates. 6. This study on dormancy breaking and germination requirements of the four species enabled us to expose, sometimes subtle, differences in germination requirements. These contrasting germination patterns were related to differences in the species' habitat preferences.

Soil depth detection by seeds and diurnally fluctuating temperatures: different dynamics in 10 annual plants

“…This is corroborated by the complete absence of light beyond the first mm in compact soils (Ciani et al 2005;Benvenuti 1995) when there are no soil cracks or aggregates (Burmeier et al 2010b). Light and response to diurnal fluctuating temperatures interact in their effect on germination (Vandelook et al 2008;Vincent and Roberts 1977), which complicates the picture for the shallowest soil layers.…”

Effects of Diverse Pretreatments on Seed Germination in Cleome gynandra L. (Capparidaceae) - A Threatened Species, Collected from Different Agro-Ecological Zones in Benin

“…These results show that there is a high genotypic variability for the physiological parameters of germination in Cleome gynandra as the recent survey of Fredrick et al (2016) demonstrated in Faidherbia albida. Salt solutions and nitrogenous compounds have often been used to break the seed dormancy (Vandelook et al, 2008;Alboresi et al, 2005;Pérez-Fernandez and Rodriguez-Echeverria, 2003;Bell et al, 1999;Hendricks and Taylorson, 1972;Mayer and PolkjaoffMayber, 1963). In the present study, we used 2 and 5 gL -1 of KNO 3 .…”

Disentangling plant establishment in sandy coastal systems: biotic and abiotic factors that determine Allagoptera arenaria (Arecaceae) germination

“…Many post-dispersal factors can have profound influence on recruitment (Roberts & Heithaus 1986;Schupp 1990;Howe 1993;Shepherd & Chapman 1998) including environmental conditions such as temperature, radiation, and water availability that greatly infl uence the development of the embryonic axis during germination (Carvalho & Nakagawa 2000;Vandelook et al 2008;Baskin & Baskin 2014), and seed predation (Janzen 1971;Howe & Smallwood 1982;Schupp 1990). Dealing with unfavorable environmental conditions (Hölzel & Otte 2004) and escaping predation often involve mutualistic interactions, such as long seed dispersal away from the mother plant (Janzen 1970;Wicklow et al 1984;Estrada & Coates-Estrada 1991;Comita et al 2014).…”