Carbon allocation in biomass is an important response of plants to the increasing atmospheric [CO2]. The effects of elevated [CO2] are scarcely reported in fructan-accumulating plants and even less in tropical wild species storing this type of carbohydrate. In the present study, the effects of high [CO2] atmosphere was evaluated on growth, biomass allocation and fructan metabolism in Vernonia herbacea (Vell.) Rusby, an Asteraceae from the Brazilian cerrado, which accumulates inulin-type fructans in the underground organs (rhizophores). Plants were cultivated for 120 days in open-top chambers (OTCs) under ambient (~380 μmol mol–1), and elevated (~760 μmol mol–1) [CO2]. Plant growth, photosynthesis, fructan contents, and the activities of fructan metabolising enzymes were analysed in the rhizophores at Time 0 and 15, 30, 60, 90 and 120 days. Plants under elevated [CO2] presented increases in height (40%), photosynthesis (63%) and biomass of aerial (32%) and underground (47%) organs when compared with control plants. Under elevated [CO2] plants also presented higher 1-SST, 1-FFT and invertase activities and lower 1-FEH activity. Although fructan concentration remained unchanged, fructan productivity was higher in plants maintained under elevated [CO2], due to their higher rhizophore biomass. This is the first report on the effects of elevated [CO2] on a plant species bearing underground organs that accumulate fructans. Our results indicate that plants of V. herbacea can benefit from elevated atmospheric [CO2] by increasing growth and carbon allocation for the production of inulin, and may contribute to predict a future scenario for the impact of this atmospheric condition on the herbaceous vegetation of the cerrado.
Overstory Community Composition and Elevated Atmospheric CO2 and O3 Modify Understory Biomass Production and Nitrogen Acquisition