Dormancy release and seed ageing in the endangered species Silene diclinis

The influence of seed testa color, temperature and seed water content on dormancy release and seed viability loss in the endangered, endemic species Silene diclinis (Lag.) M. Lainz was evaluated. Dormant heterogeneous seeds (black, red and grey colored) were exposed to three different temperatures (5, 20, and 35A degrees C) and two relative humidities (33 and 60%) in order to assay their dormancy release. Longevity behavior was studied for the three colored seeds, storing samples at nine different combinations of temperature (5, 20 and 35A degrees C) and relative humidities (33, 60 and 90%). According to our findings, seed heteromorphism was not related to neither break of dormancy nor seed storage behavior. Silene diclinis seeds present dormancy after collection, and need an after-ripening period to germinate. Temperature and relative humidity are positively correlated with dormancy release and seed ageing. Therefore, both factors must be carefully controlled during seed manipulation in the laboratory for long term seed conservation purposes. When seeds are stored immediately after collection (dormant), if the temperature of storage is above the base temperature for dormancy release found in this work (between 2.7 and 1.6A degrees C), seeds may eventually overcome dormancy. On the other hand if seeds are stored after an after-ripening period, storage at low temperature does not induce secondary dormancy.