Growth analysis of a reestablished population versus a natural population of Bidens cernua L.

A reintroduction experiment of Bidens cernua L., a species included in the Red List of Italian Flora, was carried out at Lake Posta Fibreno (Lazio, central Italy). There were no significant differences in the length of the phenological phases between the reestablished population (P(r)) and the natural one (P(n)). The length of the phenological cycle, from seedling emergence to the end of the fruiting phase, was 207 +/- 3 days. The relative growth rate in height (RGR(H)) and relative growth rate in mass (RGR(m)) were significantly (p < 0.05) higher for P(r) (0.047 +/- 0.001 cm cm(-1) d(-1) and 0.057 +/- 0.001 g g(-1) d(-1), respectively) than for P(n) (0.045 +/- 0.001 cm cm(-1) d(-1) and 0.055 +/- 0.001 g g(-1) d(-1), respectively). There were significant (p < 0.05) differences for plant height (H) and total leaf area per plant (TLA) between P(r) and P(n), the latter having the lower values. Total plant dry mass (PDM) was significantly higher for P(r), and the above-ground/below-ground dry mass ratio was 6.7 +/- 0.4 and 4.7 +/- 0.2 for P(r) and P(n), respectively. On the whole, results demonstrate that the P(r) of B. cernua has the potential to develop in a manner that is demographically similar to the P(n) present in the Posta Fibreno Lake protected area.