Efeitos da exposição ao ambiente seco sobre o crescimento e regeneração de Egeria najas Planchon (Hidrocharitaceae)

Abstract

In this study we assessed the response of some attributes of the submerged macrophyte Egeria najas to different periods of exposition to dry conditions. Ramets of E. najas were exposed to dry conditions in the laboratory for periods of 1, 2, 3 and 4 days, at 25°C. Following the exposition, the propagules were transferred to 2-liter aquaria containing water and sand, and the following attributes were measured after 15 days: propagule length, propagule dry mass, number of sproutes per propagule, sproute length, sproute dry mass, number of roots per propagule, root length and root dry mass. The results showed that sproutes and roots emerged from propagules submitted to dry periods shorter than 3 days, indicating that this species has great capacity of regeneration when submitted to dry stress: Giving this resistance to dry conditions, the transport of propagules by birds or boats may be an important mechanism of dispersion, if the time of transport is shorter than 3 days.