Title : Differential responses to precipitation peak and metallic stress in species of restinga plants from the Brazilian coastal region
This study aimed to determine whether adverse abiotic conditions were a driver of species spatio-temporal responses or whether adaptive responses are species-specific in restinga vegetation. Due to the sudden event of increased rainfall in January 2020, a scenario conducive to the observed physiological changes occurred, mainly in terms of changes in chlorophyll a fluorescence parameters (ChlF). We used analysis of the concentration of chemical elements in leaves, of the bioaccumulation factor (BAF) of essential elements and its influence on the photosynthetic response of plants, during three periods of the local rainy season: (1) January/20, (2) January during peak rainfall on the coast (Jan-Pulse) and (3) March/20, after the event. The results obtained showed higher levels of As, Cd, Cr and V in herbaceous plants, while in trees this period did not present significant differences. For BAF of essential elements, Jan-Pulse was favorable to the reduction of element content in the shoot, for BAF_Fe in herbaceous and BAF_Mn in tree species, which may be closely associated with the mobility of these metals, also dependent on soil properties. Changes observed in the chlorophyll content (SPAD index), pointed to a negative impact of high rainfall (Jan-Pulse). In terms of chlorophyll a fluorescence parameters, herbaceous plants showed positive K- and L-bands, indicating lower stability and efficiency in energy use by plants, accompanied by significantly increased energy dissipation values (DI0/RC). In relation to Jan/20, there was an increase in energy dissipation for herbaceous plants, varying between 69 and 148%, while tree plants did not show significant differences. With a similar pattern, the photosystem II performance index (PIABS) of herbaceous plants was also reduced during the Jan-Pulse. The observed results confirm a plant response gradient in relation to the coast, demonstrating that herbaceous plants, although reported as tolerant to the stress conditions inherent to the coastal region, showed losses in chlorophyll fluorescence parameters of the photochemical stage of photosynthesis in response to adverse climatic conditions and to the increased availability of water and meta(loids) in the environment.
What will audience learn from your presentation?
• Abiotic factors combined with biotic activities can also have a harmful effect on species adapted to adverse and limiting environmental conditions
• Chlorophyll a fluorescence consists of a fast and non-invasive method that allows detecting, in loco, the intensity of the impact of stressors on vegetation;
• Even in plants already adapted to unfavorable environmental conditions, the additional effect of metallic stress was detected, mainly in herbaceous species, closer to the shoreline.