Estratégias reprodutivas de Leiothrix vivipara (Bong.) Ruhl (Eriocaulaceae) na Serra do Cipó

• Autor(a) principal: Marcos Hanashiro e Silva
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFMG
• Texto Completo: http://hdl.handle.net/1843/BUOS-8ULM67
• topic: Germinação de sementes; Meristema; Campo rupestre; Pseudoviviparidade; Reprodução clonal; Botânica

Pseudovivipary is a kind of vegetative reproduction characterized by the development of plantlets on reproductive structures. This form of reproduction occurs in plants living in terrestrial environments with high seasonality such as the Arctic, highlands, or deserts.Leiothrix vivipara (Eriocaulaceae), an endemic species from the campos rupestres vegetation of the Espinhaço mountain chain in southeastern Brazil, presents this type of reproduction. The objective of this study was to anatomically characterize the development of ramets originated by pseudovivipary in L. vivipara, and evaluate the viability and germinationof seeds in the laboratory and seedling emergence under natural conditions. For morphological and anatomical analyses, the inflorescences were prepared for scanning electron and light microscopies. Viability was estimated using the tetrazolium test in fresh and in seeds stored for 12 months. Germination tests were carried out in germination chambers using 12 h photoperiod and continuous darkness under various temperatures, as well the application of gibberellic acid at concentrations of 500 and 1000 mol. Field experimentswere carried out to evaluate seedling emergence either under natural conditions or under the influence of fire. Microscopical analysis revealed that leaves were originated from the central reproductive meristem, after the end of flowers production, just before anthesis of somestaminate flowers. The new leaves are formed by a change in the fates of the meristematic cells, reassuming the production of vegetative structures, which constitute the ramets. Seed viability is high, however germination was very low under all conditions tested. The storagedid not significantly alter the viability of the seeds and gibberellin application did not promote germination. The emergence in the field reached the highest values when the seeds were sownin sterilized soil and the fire did not influence seedling emergence. The results indicate that clonal reproduction represents the largest reproductive investment of L. vivipara and despite the recruitment of seedlings being very small, their role is important to maintain genetic variability of the population.