Seed mass, seed production, germination and seedling traits in two phenological types of Bidens pilosa (Asteraceae)
Diego E. Gurvich A B , Lucas Enrico A , Guillermo Funes A and Marcelo R. Zak AA Instituto Multidisciplinario de Biología Vegetal, FCEFyN (CONICET-Universidad Nacional de Córdoba), Casilla de Correo 495 (5000), Córdoba, Argentina.
B Corresponding author. Email: dgurvich@com.uncor.edu
Australian Journal of Botany 52(5) 647-652 https://doi.org/10.1071/BT03172
Submitted: 5 December 2003 Accepted: 24 June 2004 Published: 25 October 2004
Abstract
Bidens pilosa L. is a summer annual that shows a particular phenological pattern in the Córdoba mountains, Argentina. Some individuals start flowering 1 month after germination (early type), but most of the population starts flowering 4 months after germination (normal type). The aims of this study were to (1) analyse whether differences in flowering phenology affect seed mass and seed production, and (2) assess whether possible differences in seed traits of the two parental phenological types would affect germinability, germination rate, seedling growth and flowering phenology of offspring under laboratory conditions. The study showed that the numbers of seeds per capitulum and per plant were greater in the normal type than in the early type plants. This can be related to plant height, since in the field, normal-type plants are larger than early type plants. However, early type plants produced heavier seeds than normal-type plants. Germination rate was faster in the early type seeds, but total germination was higher in the normal ones. Seedling growth, in terms of height and the date of first flowering, did not differ between the phenological types of parental seed sources. Our results showed that differences in flowering phenology were associated with seed mass and seed production differences. Seed mass appears to be related to germination characteristics but not to seedling growth nor to flowering phenology of offspring.
Acknowledgments
This research was founded by IAI (ISP III), CONICET, FONCyT, Fundación Antorchas and Darwin Initiative (DEFRA-UK). We are grateful to the Domínguez family for providing access to the study site and to M. V. Vaieretti and G. Bertone for field and laboratory assistance. Comments by A. Cingolani, L. Galetto and S. Díaz substantially improved an early version of the manuscript. We are grateful to two anonymous referees whose suggestions enhanced our manuscript. We also thank D. Abal-Solís for drawing the figures.
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