Biometria de plantas e resistência térmica dos diásporos de "Sempre- Vivas" da família Eriocaulaceae

Abstract

The everlasting has innumerable desirable ornamental characteristics and great economic and social importance in some regions of Brazil. However, they are uncultivated species that suffer from predatory exploitation, burning and the effect of global warming. The objective of this research was to review the situation of research with species of the genera Actinocephalus and Paepalanthus and to determine the spatial distribution pattern of Actinocephalus claussenianus (Körn.) Sano, Paepalanthus canastrensis Silveira and Paepalanthus chiquitensis Herzog. Given the relationship between spatial distribution and reproductive biology, it was also an objective to systematize information about ornamental potential based on the morphometric information of the vegetative and reproductive parts. In the first chapter, a survey of published and related research on the genera Paepalanthus and Actinocephalus pointed out that the genus Paepalanthus is the best reported in the 66 published works, which started in the 1970s. About 40% of the research was on floristic composition and taxonomy and the most studied species was P. chiquitensis. Actinocephalus has a smaller volume of published material, a total of 22 works, with research since the year 2004. The second chapter describes the spatial distribution, morphometry of rosettes and inflorescences and germination of the diaspores of the everlasting. For the experiments in this chapter, samples of individuals were performed in the city of Tapira-MG. The Morisita distribution index confirmed an aggregate spatial distribution pattern for the species, a greater number of P. chiquitensis individuals and a high germination capacity of the three species, with percentages above 75%. Based on morphometric information and evaluation of aesthetic components, both rosettes and scapes from A. claussenianus and P. canastrensis have ornamental potential. The third chapter analyzed the thermal tolerance of diaspores of P. chiquitensis through the percentage of germination, under laboratory conditions, with different temperatures and exposure times. The species was tolerant to high temperatures of up to 100 ºC, with an increase in the germination percentage until the exposure time of 15 minutes, possibly because the diaspores develop a state of dormancy as a form of protection from long exposures. Thermal conditioning becomes harmful, causing the death of diaspores at temperatures of 150 and 200 ° C at any time of exposure.