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

I Cortés-Fernández,A Ribas-Serra,C Cardona,L Gil,M D Cerrato,C González

doi:10.1007/s11258-021-01164-y

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.

Highlights

Coastal dune systems are considered one of the most endangered habitats, threatened by several natural and anthropogenic factors, such as sea-level rise, flooding, human trampling and infrastructures (Ciccarelli 2014; Pinna et al 2015; Gigante et al 2018)
E. maritimum grows on sandy soils, being present in dune systems where it occurs in several communities mainly in white dunes, even though it can be found in grey dunes and occasionally in other coastal or near-dune systems communities (Isermann and Rooney 2014)
A final germination percentage of 88.4 ± 0.21% was obtained in Mediterranean seeds under 12 weeks of cold stratification at 5 °C, followed by constant incubation at 20 °C, while in Atlantic seeds, the maximum mean germination of 70.22 ± 0.44% was observed at an incubation temperature of 15 °C after 20 weeks of cold stratification

Summary

Introduction

Coastal dune systems are considered one of the most endangered habitats, threatened by several natural and anthropogenic factors, such as sea-level rise, flooding, human trampling and infrastructures (Ciccarelli 2014; Pinna et al 2015; Gigante et al 2018). In this context, specific studies that focus on the species that inhabit these areas are extremely important to ensure habitat health (Valles and Cambrolle 2013). Eryngium maritimum (L.) is a species from the Apiaceae family that inhabits coastal areas of the Atlantic shores of Europe, including the British islands, the west and east Mediterranean coasts, and more sparingly the Black and Azov Sea coasts (Isermann and Rooney 2014). As a result of the distribution of ice cover, permafrost and sea surface temperatures in that period, the distribution area of the species must have been dramatically reduced in West, Central and North Europe, while in the Western Mediterranean, temperatures might have been

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