Seed response to temperature of three Nothofagus species distributed across an altitudinal gradient in the South Andes

ARANA, MARÍA VERÓNICA; GONZALEZ POLO, M; MARTINEZ MEIER, A; SÁNCHEZ, RA; BENECH-ARNOLD, R; GALLO, LA; SÁNCHEZ, RA; BENECH-ARNOLD, R; BATLLA, D

Mar del Plata

Congreso; XXIX Reunión Argentina de Fisiología Vegetal; 2012

Sociedad Argentina de Fisiología Vegetal

Seed response to temperature of three Nothofagus species distributed across an altitudinal gradient in the South Andes Arana MV1, Gonzalez-Polo M2, Martínez-Meier A1, Gallo L1, Sanchez RA3, Benech-Arnold R3, Batlla D3 1INTA, Río Negro, Argentina, 2Universidad del Comahue INIBIOMA-CONICET, Río Negro, Argentina 3IFEVA-CONICET, Universidad de Buenos Aires, Argentina. Seed germination is the earliest event in plant life cycle, and therefore it constitutes a relevant process for adaptation since it sets the environmental context for subsequent development and natural selection.   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, three Nothofagus species, N. obliqua (Roble), N. nervosa (Raulí), and N. pumilio (Lenga) are distributed across a clear altitudinal range; Roble: 600-900 meters above sea level (asl), Raulí: 800-1100 asl and Lenga: 1000-1700 asl.  Temperature is the environmental factor that shows the stronger association with altitude, suggesting the existence of different thermal niches.  The aim of this work is to study germination behavior of Roble, Raulí and Lenga, in order to evaluate the possible contribution of this trait to the species? distribution across the altitudinal range.  Using a threshold modeling approach, we compared thermal population parameters between species, as indicative of differential responses of seeds to temperature.  In addition, we studied dormancy loss in the field, to validate the models and unravel differences in seed behavior between these species? under natural conditions. Data will be discussed in the context of possible adaptation in germination to thermal environments and its potential contribution to emergence patterns across the altitudinal range.