IFEVA   02662
INSTITUTO DE INVESTIGACIONES FISIOLOGICAS Y ECOLOGICAS VINCULADAS A LA AGRICULTURA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Ecophysiological bases of seed germination of two Nothofagus species distributed across an altitudinal gradient in the South Andes
Autor/es:
ARANA, M. VERÓNICA; GONZALEZ-POLO, MARIANA; MARTINEZ MEIER, M; SANCHEZ, RODOLFO; BENECH-ARNOLD, ROBERTO; GALLO, LEONARDO
Lugar:
Salvador, Bahia
Reunión:
Congreso; 10th Conference of the International Society for Seed Science: "Seed Science in the 21th Century"; 2011
Resumen:
Germination
behavior is one of the earliest phenotype expressed by plants and this
fact has consequences for the evolution of post-germination traits,
ecological niches and geographic ranges of species (Donohue et al 2010
Annu. Rev. Ecol. Evol. Syst. 41:293319). Across the South Andes Mountains,
it is possible to distinguish several environmental gradients although
the pluviometric and altitudinal ones are probably exerting the stronger
influence in the distribution and abundance of the tree species of the
region. In the western Andes, around the 36° 30 and 40° 10 latitude
south, two Nothofagus species, N. obliqua (roble) and N. nervosa (raulí), are distributed across a clear altitudinal range (roble: 600-900 meters
over the sea level (msl), raulí: 900-1000 msl). The aim of this work is
to study the germination behavior of these species in order to evaluate
the influence of this trait in the definition of their ecological
niches. Our results indicate that, in both species, cold stratification
decreases the level of seed dormancy and that red light (R) promotes
germination even at constant temperature. Whereas alternating
temperatures were able to replace the R requirement for the stimulus of
germination in raulí, the seeds of roble showed a stronger dependence on
both factors. Seed morphology (bi or tri winged seeds) was associated
with the germination physiology in both species. Field studies showed
that seedling emergence is weakly associated with the environmental
light quality, and therefore in addition to light, other factors such as
temperature and soil water potential might be more relevant for the
control of germination under natural conditions. Work in progress to
address this last involves hidro-termal time models and field
measurements in permanent plots across the altitudinal gradient.