Germinación de Baccharis dracunculifolia subsp. tandilensis: caracterización basada en la temperatura, la luz y la salinidad

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.

Germination responses in Zephyranthes tubispatha seeds exposed to different thermal conditions and the role of antioxidant metabolism and several phytohormones in their control

“…Fitting the three-parameter non-linear function to cumulative germination data satisfactorily described the germination dynamics of this native species, as already shown for other native species like Baccharis dracunculifolia subsp. tandilensis (Manfreda et al, 2020) and Rhodophiala bifida , a closely related species to Z. tubispatha (Acosta et al, 2021). Despite the fact that total germination percent at 7°C did not significantly differ from the 20°C (control) treatment, an important delay in both germination onset and rate (coefficient B ) was observed, leading us to the conclusion that the minimum temperature for optimum germination in Z. tubispatha seeds was clearly above 7°C.…”

“…Cumulative germination per sampling unit was characterized through non-linear regression by fitting the following equation: % G = A *(1 − 1/(1 + ( t / B )^ k )) (Geshnizjani et al, 2018; Manfreda et al, 2020). Coefficient A is an asymptotic value equivalent to the Gm percent (i.e.…”

Vegetation of a hill grassland of the Paititi Natural Reserve (Pampa biome) and early detection of non-native species acting as invasive

“…In particular, for Baccharis dracunculifolia ssp. tandilensis and Senecio selloi, changes in habitat preference have been reported in the area: B. dracunculifolia extending from the hills to the plains near the Atlantic Ocean coast (Scaramuzzino et al, 2015;Manfreda et al, 2020) and S. selloi to grasslands dedicated to livestock grazing (Fernández, 2011). Therefore, new surveys in the province could yield information that accounts for the current distribution of native species in ecosystems close to the studied one and thus clarifying the threatened status of the species and eventually incorporating new taxa into the plant red list.…”

Sexual and asexual propagation of Baccharis dracunculifolia DC., a dioecious medicinal Brazilian shrub

“…Furthermore, many wild species have different flowering times both within the population and within individuals, which may provide a significant portion of immature seeds (Hay & Probert, 2013) and, consequently, different germination rates. The germination of this species responds positively to light and temperatures of 20-28°C, with thermo-inhibition at 35°C (Manfreda et al, 2020). Grzybowski et al (2016) conducted a study with seeds of Vernonanthura discolor, a native plant from Brazil, and reported their germination at 20 or 25°C with light supply or 25°C in the dark.…”

“…Despite the ecological and economic importance of this plant, information about the propagation of the species is limited. The natural method of reproduction of B. dracunculifolia is by diaspores, but only a few studies on germination are available in the literature (Gomes & Fernandes, 2002;Manfreda, Alcaraz, & Scaramuzzino, 2020), and important information such as the optimal point of harvest, which is an essential factor for obtaining high-quality plant material, is absent. The optimal point of seed harvesting is established by the point of physiological maturity, identified by the maximum dry mass accumulation (Rajou et al, 2012).…”