Germination of Baccharis dracunculifolia subsp tandilensis: Characterization based on temperature, light, and salinity

Abstract

Baccharis dracunculifolia is a South American dioecious shrub of the Asteraceae family, with a wide geographic distribution and potential use for recovery of degraded areas, ornamental and medicinal purposes. There are two subspecies: B. dracunculifolia subsp. dracunculifolia and B. dracunculifolia subsp. tandilensis. The latter is endemic to the Tandilia hills system in Argentina and recently was recorded its expansion to another environment, the coastal dunes in the Buenos Aires province. The aims of this research were to characterize the germination of B. dracunculifolia subsp. tandilensis according to temperature and light, and to compare the germination in saline conditions of seeds coming from hills (A) and marine coastal dune environment (C). Germination responds positively to light without showing another important type of primary dormancy. Thermal time was 2500°Ch (104°Cd) and base temperature of 6°C, without temperature germination constraints between 20-28°C and thermo-inhibition at 35° C. Response to NaCl concentrations was similar between seeds from environments A and C, both showed strong germination inhibition at 100 mM of NaCl and higher concentrations. These results are discussed in relation to environmental conditions and in comparation whit physiological characteristics reported for subsp. dracunculifolia and other species within the genus Baccharis.