Germination responses of erica andevalensis to different chemical and physical treatments

Ecol Res (2009) 24: 655–661 DOI 10.1007/s11284-008-0536-7

O R I GI N A L A R T IC L E

´ S. Rossini Oliva Æ E. O. Leidi Æ B. Valdes

Germination responses of Erica andevalensis to different chemical and physical treatments

Received: 14 April 2008 / Accepted: 1 July 2008 / Published online: 12 August 2008 Ó The Ecological Society of Japan 2008

Abstract Erica andevalensis Cabezudo &Rivera is a threatened edaphic endemic species of Andalusia (SW Spain). Under natural conditions, the plants produce a very large number of small seeds (0.3–0.4 mm) but very few seedlings survive. Different treatments (high temperature, cold pre-treatment, nitrogen salts, and gibberellic acid applications) were tested to assess germination patterns in different populations and to determinate the mostfavorable conditions for germination. Gibberellic acid was provided in five different concentrations from 0 to 400 ppm GA3, while nitrogen was applied as 10 mM of either KNO3 or NH4NO3. The effect of pH on germination was also tested. The species always showed a low germination rate (6.50–22%) that was not stimulated either by 1 or 4 months in dry cold pre-treatment, nitrogen application, acid pHmedium, or by high temperature (80°C for 10 min); although gibberellic acid application (100–400 ppm) significantly enhanced germination. The highest percentage of germination (41.6%) was achieved with a mean germination time to start germination (t0) of 7.6 ± 0.54 days when the seeds were subjected to 400 ppm gibberellic acid treatment. The population origin did not have a significant effect ongermination percentage. Keywords Ericaceae Æ Seeds Æ Gibberellic acid Æ Endemic

Introduction
Erica andevalensis Cabezudo & Rivera (Ericaceae) is a ´ shrub distributed in the Andevalo area (SW Spain) and the Algarve (S Portugal). It seems not to be intrinsically endangered but it is considered as a vulnerable edaphic endemic species following the IUCN (International Union for the Conservation ofNature) categories (VU, IUCN) and autonomic classification. The species flower mainly in the summer but in the field, plants flower throughout the year. Its fruits ripen 30–50 days after flowering and are spherical capsules with 40–130 ovoid ´ seeds of 0.3–0.4 · 0.26–0.28 mm. The Andevalo is known for its ancient mining activities where pyrite was mined for copper, gold, and silver (Asensi et al. 1999) andthe soils of the area are extremely acidic with a high concentration of iron oxides and heavy metals (Rodrı´ guez et al. 2007). The species may represent a valuable element in the re-vegetation projects of mining area because its ornamental flowers that blossom from June to December. It is well known that appropriate low or high temperature, light conditions, nitrate, or hormonal treatments mayfavor germination in many species. Many seeds that respond positively to light also respond positively to NO3À (Bungard et al. 1997; Cruz et al. 2003). Fire may influence germination via the production of heat, ash, charate, change in micro-sites and volatile chemicals (Baskin and Baskin 1998). Heat presumably damages the seed coat making it permeable and facilitating imbibition of the embryo (Baskinand Baskin 1998), as demonstrated in several studies on woody ´ shrubs (Gonzalez-Rabanal and Casal 1995; Herranz et al. 1998; Rivas et al. 2006; Yang et al. 2007). It was suggested that nitrogenous compounds are the postfire inducing agents of seed germination in the field (Thanos and Rundel 1995; Keeley and Fotheringham 1997; ´ ´ Perez-Fernandez and Rodrı´ guez Echevarrı´ a 2003) and that have arole as dormancy breaking agents since nitrogen oxides may increase the permeability of the

´ S. Rossini Oliva (&) Æ B. Valdes Department of Plant Biology and Ecology, University of Seville, Avda. Reina Mercedes s/n, Apartado de Correo 1095, 41080 Sevilla, Spain E-mail: sabina@us.es Tel.: +34-954-557056 Fax: +34-954-557049 E. O. Leidi Department of Plant Biotechnology, IRNAS-CSIC, Avda. Reina...