Germination and cryopreservation tolerance of seeds from the rare aromatic species Thymus lotocephalus

Thymus lotocephalus G. López and R. Morales is a rare aromatic species endemic from the south region of Portugal. We investigated the germination behavior and the cryopreservation tolerance of T. lotocephalus seeds collected from four populations. Seeds were set to germinate at 15 or 25 ◦C under light or darkness. The best germination temperature tested was 15 ◦C, under either light or darkness, with final germination percentages above 80% and mean germination time (MGT) below 10 days. The results showed that T. lotocephalus has non-dormant seeds. Seeds from different populations presented few differences on the final germination percentage and MGT. To assess seed tolerance to cryopreservation, they were directly immersed in liquid nitrogen for 30 days. Overall, we found that cryopreservation was non-detrimental to germination of T. lotocephalus seeds, thus being a reliable method for germplasm conservation of this endangered species.N. Coelho and S. Gonçalves acknowledge grants SFRH/BD/63501/2009 and SFRH/BPD/31534/2006 from the Portuguese Science and Technology Foundation (FCT)