Evidence of interpopulation variation in the germination of Eryngium maritimum L. (Apiaceae)

Abstract

Germination is considered as one of the most crucial steps in a plant’s lifetime. The germination of Eryngium maritimum, a dune species located across all European coasts, has been extensively analysed in Northern populations, where it is considered a locally endangered species. However, less attention has been given to southern populations, where the knowledge about the germination of the species is very limited. The main objective of the present study was to analyse the effect of cold stratification in one Mediterranean and one Atlantic population of the species, as well as to compare the potential variation of seed dormancy among a latitudinal gradient in European populations based on current literature. Seeds collected from Mallorca (Mediterranean, Spain) and Asturias (Atlantic, Spain) were germinated at different temperatures and cold stratification periods ranging from 4 to 20 weeks. These results were merged with the results of previous studies to test the potential effect of latitude and climatic variables in germination. Although the optimal incubation temperature was 10 ºC, the highest final germination percentages (up to 96%) was obtained in both populations combining specific cold stratification periods (5 ºC) and constant incubation temperatures (15–20 ºC). Atlantic seeds needed longer cold stratification times to reach high germination percentages compared with Mediterranean seeds. Apart from the stratification response, significant differences in viability and in germination were observed between the Atlantic and the Mediterranean populations. Considering data from previous studies in the analysis, the results suggest that there is a potential effect of latitude in the ecological germination requirements, by which the higher the latitude, the longer the cold stratification period required to germinate, with a correlation with the mean annual temperature. These results suggests that two factors, modulation of dormancy relating to adaptative or maternal effects and viability, govern the germination of the species.

Unraveling the Effects of Cold Stratification and Temperature on the Seed Germination of Invasive Spartina alterniflora Across Latitude

“…Invasive plant populations are likely very plastic and can adapt to different local environments ( Feng et al, 2009 ; Liu et al, 2017a ), and their traits will co-vary with these conditions that vary with latitude and altitude ( Colautti et al, 2009 ; Castillo et al, 2014 ). Although it is difficult to determine the balance of genetic vs. environmental influence ( Weng et al, 2006 ; Cortés-Fernández et al, 2021 ), our results indicate that S. alterniflora , which is distributed over a wide latitudinal range, may have significant adaptive variation in seed germination.…”

“…The responses of seeds from different latitudes to stratification were significantly different ( Fowler and Dwight, 1964 ). This is because low-latitude populations lack a cold stratification requirement, and high-latitude populations experience cold temperatures and need cold stratification to release dormancy ( Weng et al, 2006 ; Cortés-Fernández et al, 2021 ). Reproductive traits, such as seed set and seed survival of S. alterniflora also increase with latitude ( Liu et al, 2017a ).…”

The role of E. maritimum (L.) in the dune pollination network of the Balearic Islands

“…The main hypothesis is that E. maritimum is visited by a great number of pollinators, as attending to previous studies the capacity of the species to self‐fertilize is low, as well as its anemophily, which suggests that the species is strongly entomophilous (Cortés‐Fernández, Cerrato, Ribas‐Serra, & Gil Vives, 2022 ). This study will give light to the ecology of the species in the Balearic Islands, continuing a series of studies which analyzed its reproductive biology, germination and salinity tolerance in this area (Cortés‐Fernández et al, 2021 ; Cortés‐Fernández, Cerrato, Ribas‐Serra, & Gil, 2022 ; Cortés‐Fernández, Cerrato, Ribas‐Serra, & Gil Vives, 2022 ).…”

“…Its role in the coastal pollination network has never been assessed, and its pollinators are unstudied, with only a few studies that give light to some of its pollinators (Gil, 1994 ) and most of them carried out in Northern European populations (Fitter & Peat, 1994 ; Hegi, 1935 ; Westrich, 2001 ; Zanella et al, 2009 ), where it is considered as a highly‐threatened species (Aviziene et al, 2008 ; van der Maarel & van der Maarel‐Versluys, 1996 ). In Northern populations, it displays low fruit and seed set production, and conversely, Balearic populations exhibit high fruit and seed set, with low levels of incompatibility (Cortés‐Fernández et al, 2021 ). These differences could be related to pollinators but, to validate this hypothesis, firstly it is compulsory to understand how the species behaves in Mediterranean populations, where its populations exhibit a good conservation status.…”