Aridity level, rainfall pattern and soil features as key factors in germination strategies in salt-aﬀected plant communities
In arid environments, particularly in halophytic habitats, germination ecophysiology is strongly aﬀected by environmental factors, primarily water availability, which is inﬂuenced by quantity and seasonal distribution of precipitation and soil properties. The aim of this paper was to demonstrate that water availability is essential for the control of germination and the response of seedlings growing in saline areas. With this approach, we compared the germination strategies in two Halocnemum populations with contrasting rainfall regimes and soil aridity. The germination behavior and radicle growth under various temperature regimes, light conditions and salinity levels were evaluated. Diﬀerences were found for all parameters between the populations. Seeds from the drier Mediterranean population exhibited common opportunistic behavior and germinated in a wide range of conditions, whereas germination in the Temperate population preferred conditions with light and was restricted to alternating temperatures, adaptations to temporary waterlogged environments. This restriction was eliminated when seeds were previously exposed to high salt concentrations, which conﬁrmed an osmopriming eﬀect. Based on our results, the development of global conservation plans for species with large distributions is not recommended. Successful management plans for threatened habitats should consider single populations and the reproductive strategies that developed in response to local environmental conditions.