Local conditions effects on seed germination of Hypericum balearicum L. in response to temperature

Temperature, which is one of the most relevant abiotic factors affecting seed germination, is strongly influenced by local site conditions. Here, we collected seeds of Hypericum balearicum, an endemic shrub of the Balearic Islands, from 11 sites of Mallorca. We investigated variations in final germination percentage (FGP), germination rate (t50) and germination timing (t0) of seeds from different provenances according to the local conditions of each location (here classified in mountain, coast and valley environment) under a range of temperature treatments (12–24 oC). An environmental data logger was installed in three of the sites to determine the temperature variability for each environment. Hypericum balearicum germinates in the optimal temperature range of Mediterranean plants. FGP was neither affected by temperature treatments nor by the site of origin (environment). However, the coast environment showed higher t50 and t0 values in all temperatures tested compared to mountain and valley, especially at low temperatures compared to mountain environment and at low and high temperatures compared to valley environment. These differences among environments were consistent with the temperature parameters recorded in each environment. Overall, this study demonstrates the importance of taking into account local temperature conditions effects in germination in order to know how plants will respond to environmental changes.