Effect of alternating temperature and seeds storage duration on the germination of Thymus satureioides

Abstract

Thymus satureioides Cosson is an endemic chamaephyte to Morocco and Algeria. It belongs to the Lamiaceae family and commonly used in traditional medicine. Its over-exploitation threatens its sustainability in many ecosystems in Morocco. This study aims to explore the effect of environmental factors (temperature and storage) on the germination capacity of the seeds of this species in order to contribute to contribute to the rehabilitation of degraded ecosystems of T. satureioides. Accordingly, seeds collected from natural plant populations were subjected to six alternating temperatures (40/25, 35/20, 30/15, 20/10, 15/5 and 10/0 °C with a 14/10 hr. thermoperiod) and three storage duration (3 years, 5 years and 8 years) under ambient laboratory conditions. The results indicate that the alternating temperature and the seed storage duration have a significant effect on the germination parameters according to the test of Student Newman and Keuls (SNK). The highest germination percentage 93% was recorded for the alternating temperature of 15/05 °C, while high alternating temperature 40/25 °C strongly inhibited the seed germination. The 20/10 °C temperature regime was the best in terms of higher capacity and speed germination as indicated by the germination index (7.7 %/day for 20/10 °C versus 0.5 %/day for 10/0 °C). Furthermore, these results show that seed stored for longer duration delayed germination and decreased the germination capacity and rate. Seeds stored at room condition retain seeds viability up to 3 years. However, after 5 and 8 years of storing, the germination percentage was significantly reduced (75.0 and 64.5% respectively), which also suggests a reduction of seed viability.

Keywords

• ligneux bas, germination, température
• stockage
• longévité
• réhabilitation