Provenance rather than nitrogen addition dominate the phenotypes and plasticity of Ambrosia artemisiifolia in China

Phenotypic plasticity, which differs between species, populations,
individuals, even traits, is considered as one of the mechanisms of plant
invasion. We conducted a common garden experiment with six provenances
(HRB, CC, HG, ML, MZ, LB) of Ambrosia artemisiifolia and three nitrogen
addition treatments to test their performance response. In order to
explore the adaptation strategies of A. artemisiifolia towards
heterogeneous habitats, phenotypic plasticity indexes were calculated to
analyze among different provenances and traits. All traits were
significantly influenced (P<0.05) by provenance, except for number
of inflorescences, inflorescences length and intercellular CO2
concentration. Nitrogen addition notably affected on seed length, root
biomass ratio, root-shoot ratio and four physiological traits (Pn, Tr, Gs,
Ci). Among six provenances, the phenotypic plasticity index differed
significantly (P<0.05), but there were no significant differences
of plasticity among nitrogen treatments. And biomass phenotypic plasticity
was relatively higher both in response to prevenance and to nitrogen. We
also found that only the plasticity of 100-seed weight was closely related
to latitude, climate and genetic factors. In summary, provenances had a
greater impact on the phenotype and plasticity of A. artemisiifolia than
nitrogen addition, indicating the potential for further evolution of
plasticity. Differences in plasticity among provenances and traits are
important in predicting the invasion trend of A. artemisiifolia in the
future.