CO₂ Fertilizer Effect on Growth, Polyphenols, and Endophytes in Two Baccharis Species

Abstract

In a climate change context, the buildup of CO₂ will affect plant communities worldwide. This study evaluated the effects of CO₂ enrichment on the development and defense of two Cerrado native species Baccharis dracunculifolia and B. platypoda and their associated endophytic fungi richness. The study took place in Open-Top Chambers, two with ambient CO₂ concentration (~400 ppm) and two in an enriched environment (~800 ppm). Baccharis platypoda developed 20% more leaves under enriched CO₂ conditions, whereas B. dracunculifolia was 30% taller and showed 27% more leaves than those under ambient conditions. In both species, leaf polyphenol concentration did not differ between treatments. Nevertheless, polyphenol content had a positive correlation with plant height on both species’ individuals grown under CO₂ enriched conditions. Endophytic fungi richness and colonization rate on both plant species did not differ between ambient and enriched conditions. Our results show the positive effect of CO₂ fertilizer in at least one of the measured growth parameters. An important new finding was a synergistic increase in growth and chemical defense in both studied species under enriched CO₂ conditions, suggesting higher carbon assimilation and accumulation. This study suggests that the effects on primary productivity and secondary metabolites of Baccharis species will potentially reflect on the diversity and distribution of Cerrado plants and their associated animal communities.

Keywords:
cerrado; climate change; carbon dioxide; functional homogenization; secondary metabolites