Annual dormancy cycles in buried seeds of shrub species: germination ecology of Sideritis serrata (Labiatae)

Abstract

The germination ecology of Sideritis serrata was investigated in order to improve ex-situ propagation techniques and management of their habitat. Specifically, we analysed: (i) influence of temperature, light conditions and seed age on germination patterns; (ii) phenology of germination; (iii) germinative response of buried seeds to seasonal temperature changes; (iv) temperature requirements for induction and breaking of secondary dormancy; (v) ability to form persistent soil seed banks; and (vi) seed bank dynamics. Freshly matured seeds showed conditional physiological dormancy, germinating at low and cool temperatures but not at high ones (28/14 and 32/18 °C). Germination ability increased with time of dry storage, suggesting the existence of non-deep physiological dormancy. Under unheated shade-house conditions, germination was concentrated in the first autumn. S. serrata seeds buried and exposed to natural seasonal temperature variations in the shade-house, exhibited an annual conditional dormancy/non-dormancy cycle, coming out of conditional dormancy in summer and re-entering it in winter. Non-dormant seeds were clearly induced into dormancy when stratified at 5 or 15/4 °C for 8 weeks. Dormant seeds, stratified at 28/14 or 32/18 °C for 16 weeks, became non-dormant if they were subsequently incubated over a temperature range from 15/4 to 32/18 °C. S. serrata is able to form small persistent soil seed banks. The maximum seed life span in the soil was 4 years, decreasing with burial depth. This is the second report of an annual conditional dormancy/non-dormancy cycle in seeds of shrub species.

Dormancy cycles in buried seeds of three perennial Xyris (Xyridaceae) species from the Brazilian campo rupestre

“…This mechanism prevents germination from occurring under unfavourable periods for seedling establishment, enhancing survival of plant populations, especially in annual species (Schütz ; Copete et al . ). Thus, seed dormancy cycles are an important strategy in species inhabiting seasonal environments, where favourable conditions for germination and seedling survival are restricted to certain times of the year (Baskin & Baskin ).…”

Hydrothermal sensitivities of seed populations underlie fluctuations of dormancy states in an annual plant community

“…However, Huang et al (2016) did not explore the dormancy alleviation/cycling process (i.e., the change of dormancy state) during after-ripening, which is an important life history trait in this desert annual community (Adondakis and Venable 2004). Dormancy cycling has been suggested as an important adaptation to specific habitats (Baskin and Baskin 1985, Baskin et al 1993, Finch-Savage and Footitt 2017, and is found in diverse plant forms in addition to annual plants (e.g., Cao et al 2014, Copete et al 2015. Huang et al (2016) reported only on seeds that had been after-ripened for 4-5.5 months and therefore had largely lost the primary dormancy present in freshly matured seeds.…”

Inducción de latencia en semillas desecadas de Scorzonera reverchonii (Compositae) conservadas a baja temperatura

“…También son inducidas a latencia secundaria por bajas temperaturas semillas hidratadas de especies de matorral como Sideritis serrata Lag. (Copete et al 2015) y de varios geófitos con latencia morfofisiológica simple y profunda del epicótilo, como ocurre en Narcissus hispanicus Gouan (Copete et al 2011), N. eugeniae Fern. Casas (Copete et al 2014) y N. radinganorum Fern.…”