Temperatura e luz na germinação do endemismo algarvio Tuberaria major

Dissertação mest., Gestão Sustentável de Espaços Rurais, Universidade do Algarve, 2009

To increase the knowledge about the germination physiology of Tuberaria major (Willk.) P.Silva & Rozeira, an endemic Portuguese species that only flourishes in the Algarve (Portugal), we analyzed the influence of heat treatments and mechanic scarification, before seeding, in the germination process. The effect of two types of lighting (incandescent lamps and natural light) on the germination process was also assessed. The seeds were submitted to temperatures between 40ºC and 140ºC (dry heat), with different exposure times, (2 and 5 days at 40ºC and 60ºC and 1, 5 and 10 minutes at temperatures between 80ºC and 140ºC), to simulate direct sun exposure during Summer or a fire event. Mechanic scarification was carried out using sandpaper or regular sand. Germination occurred at 15ºC in the dark, when light was not a treatment, and was assisted for 60 days. Germination was dramatically increased by the heat treatments at 100ºC and 120ºC and by the mechanic scarification with sandpaper. Sixty days after seeding, percentage of germinated seeds was close to zero in the control and ranged from 60% to 90%, in the treatments at 100ºC and 120ºC, depending on the exposure time. In seeds exposed to 120ºC the germination was conditioned by the maximum exposure time of 1 minute. Treatments at 120ºC with exposure times superior to 1 minute or with temperatures superior to 120ºC led to no seed germination. The light factor doesn´t seem to have a dramatic effect in Tuberaria major germination. However germination in dark seems to be slightly superior, especially in treated seeds and under natural light. Scarification with sandpaper led to germinations higher than 90%. Thus it seems like these seeds are seeds with a primary physical dormancy (hard coat) that may be overcome by mechanic abrasion or fire occurrence.