Seed mass, seed production, germination, and seedling traits in two phenological types of Bidens pilosa L. (Asteraceae)

GURVICH D., ENRICO L., FUNES G & ZAK M

AUSTRALIAN JOURNAL OF BOTANY

CSIRO

Lugar: Sydney; Año: 2004 vol. 52 p. 647 - 652

0067-1924

Abstract.   Bidens pilosa L. is a summer annual that shows a particular phenological pattern in the Córdoba mountains, Argentina. Some individuals start their flowering one month after germination (early type), while the greatest proportion of the population starts its flowering five months after germination (normal type). The aim of this study was 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 in lab conditions. The study showed that the number of seeds per capitulum and per plant was 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 height, and the date of the 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.