HOW SHORT-TERM STORAGE AFFECT SEED GERMINATION FEATURE OF THREE MEDITERRANEAN MEDICINAL PLANTS

The whole Mediterranean region undergoes a unprecedented biodiversity crises reflected by drastic environmental transformation, therefore the present investigation aimed to better understand the fact of short conservation process on seed germination of selected species which are submitted to serious threats in those natural habitats. Germination patterns were assessed for seeds of Ballota hirsuta, Marribium vulgare and Thymus fontanesii stored for one, two and four months at warm, low and freezing temperatures (20, 5 and - 20°C respectively) after to have undergo an after-ripening of three months through ambient laboratory conditions. The germination trials were implemented at optimum germination temperature (20°C). Higher and quickest germination was showed for seeds which had been held at 20°C during 2 months for B. hirsuta and T. fontanesii (76% and 88% respectively) and during 1 month for M. vulgare (73%); though warm temperature is seemed to be advisable for short term storage, however significant germination decrease was recorded by rising storage time (4 months) even at warm temperature. Seeds of B. hirsuta and M. vulgare kept at -20 and 5°C showed low germination capacity. Surprisingly, T. fontenesii seeds which were held for 4 months kept high viability even at -20°C. Probably, B. hirsuta and M. vulgare avoid seed worsening in their natural habitats by spreading fructification period which lead to decrease the rest phase of seeds within ground. However, T. fontanessi seeds remained viable even at low and freezing temperatures. Seed conservation of the three studied species is intimately linked to both duration of storage time and temperature, thus T. fontanessi seeds are more adapted to the formation of persistent soil seed banks.