Improvement in light utilization and shoot growth in Hymenaea stigonocarpa under high CO ₂ concentration attenuates simulated leaf herbivory effects

ABSTRACT

This study evaluated the photochemical responses of photosystem II and growth of Hymenaea stigonocarpa under CO₂-enriched conditions with exposure to simulated herbivory events. After herbivory simulation in two distinct parts of the stem of plants (apex and base), chlorophyll a fluorescence, chlorophyll index, growth, extrafloral nectary density, leaf mineral nutrition, and biomass production were evaluated. Plants of H. stigonocarpa grown under high [CO₂] after simulated herbivory in the apical part of the stem had higher electron transport rate, effective quantum yield of photosystem II, and chlorophyll contents. However, simulated herbivory in the basal portion of plants grown under high [CO₂] increased plant height, branch and root length, leaf number, leaf area, node number, and leaf expansion rate. In conclusion simulated herbivory at the basal portion and high [CO₂] induce positive responses in H. stigonocarpa, leading to the allocation of biomass to vegetative parts related to the capture of resources such as water and light. Apical leaves could compensate for the elimination of part of their leaf blades by increasing their photosynthetic yield. Thus, the increase of [CO₂] attenuated the adverse effects of leaf removal on H. stigonocarpa plants by inducing photosynthetic improvement and growth after the loss of leaf tissue.

Keywords:
biomass allocation; Cerrado; climate change; leaf damage; leaf development