O papel do fogo nas sementes de leguminosas arbóreas de cerrado e floresta

• Autor(a) principal: Bonani, Nathalia [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/11449/155805; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2017-08-24/000889758.pdf
• topic: Sementes; Sementes - Desenvolvimento; Fogo e ecologia; Germinação; Sementes - Viabilidade; Ecologia vegetal; Leguminosa; Cerrados; Florestas

Fire is an important factor in the dynamics of various plant communities such as the savanna formations. Species from Fabaceae family are found in both forests and Cerrado areas often presenting physical dormancy that can be broken in most cases by exposure to high temperatures. Thus, this work aims to verify the role of fire in germination and resistance of legume trees, comparing species from Cerrado and forest. In all, nine species were studied, three from forest, four from Cerrado and two with occurrence in both environments. The hypothesis was that Cerrado species seeds would have a higher resistance to fire exposure and could have their dormancy broken with increasing temperatures, whereas forest species seeds would have their viability reduced when exposed to heat shocks. All species also had their seed traits (mass, shape, permeability, water content) and germination (germination and resistance to high temperatures) measured. For heat shock tests we used four treatments (control, 100°C for 1 minuto and 3 minutos and 200°C for 1 minute) with 5 replicates each (20 seeds/treatment/species). After the treatments, the seeds were placed in germination chambers for 30 days at 27°C with photoperiod of 12 hours and germination counting performed 3 times a week. All species survived after exposure to 100°C, what seems to be important for species maintenance facing disturbance and environmental changes. In the Cerrado environment, even some small-sized seeds (Anadenanthera peregrina e Stryphnodendron obovatum) resisted the 200°C heat shock. The small size of seeds seems associated to the disturbed Cerrado system and it is not related to seed resistant to fire. Water content and seed shape had no apparently relation with the environment of occurrence. Forest species had impermeable (Schizolobium parahyba) or permeable (Anadenanthera colubrina) seeds, whereas species occurring in both environments and Cerrado had fractions of dormant and...