Resistência ao fogo e atributos funcionais em sementes de leguminosas de campo sujo

• Autor(a) principal: Nunes, Jessika da Silva [UNESP]
• Data de Publicação: 2016
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/155806; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2017-08-24/000889760.pdf
• topic: Ecologia vegetal; Cerrados; Sementes - Dormência; Leguminosa; Germinação; Fogo e ecologia; Comunidades vegetais; Sementes; Queimada; Sementes - Viabilidade

Fire influences the Cerrado vegetation, affecting the dynamics of plant communities. Fabaceae species are common in these areas, showing seeds with impermeable coats. The impermeability of seed coat is called physical dormancy and factors such as fire-related heat shocks have been recognized to break it in some flammable ecosystems from Australia and the mediterranean. Moreover, for the persistence of those populations at sites influenced by recurrent fires, the seeds should be resistant to high temperatures. Therefore, this study aims to evaluate seed germination and seed traits of legumes from Cerrado open savannas (campo sujo) (8 species: 2 subshrubs, 3 shrubs, 3 trees) in relation to fire. Since the study species occur in an environment with frequent influence of fire, we hypothesized that the seeds would resist the exposure to high temperatures, and would have similar traits, so disturbance acts as an environmental filtering. To analyse the effect of high temperatures we used 5 replicates of 20 seeds/treatment. The following treatments were applied: 100°C for 1 and for 3 minutes, and 200°C for 1 minute, and a control, which was not exposed to any heat shock. After the treatments, the seeds were put to germinate in a germination chamber (27°C, 12h of light) for 30 days, with regular counting of germination, and a viability test (tetrazolium) was performed by the end of the experiment. The results show that all seeds survived the heat shock of 100°C 1', and two species exhibit break of physical dormancy when exposed to the treatment of 100°C 3' (Senna cana and Mimosa kalunga). S. cana had also dormancy breaking when exposed to 200°C. On the other hand, six species had some reduction in germination and/or viability in the treatments considered more severe, 100°C 3' and 200°C. All species had similar traits, with values that classified them as round-shaped (<0.2), and seed mass values ≤0,05g, showing also low water content (<10%)...