Climate change and the growth of Amazonian species seedlings: an ecophysiological approach to Euterpe oleracea

Abstract

Climate change threatens many native species from the Amazon Forest. Among the endangered species is the Açaí (Euterpe oleracea), which is a species with great national and international interest, due to the nutritional benefits and medicinal properties of its fruits. However, there is still no information on the ecophysiological responses of Açaí to climate change. Thus, the objective of this work was to evaluate the effect of increased temperature and CO2 concentration change on the ecophysiology of Açaí seedlings. To do so, Açaí seedlings were subjected, for 90 days, to three different climatic scenarios: current Amazon; RCP4.5 (current average temperature in the Amazon + 2.5 °C and 538 ppm of carbon dioxide concentration, i.e. CO2); and RCP8.5 (+ 4.5 °C and 936 ppm of CO2 concentration). In addition, two irrigation levels were applied within each climatic scenario: seedlings maintained at 90% (not stressed) and 40% (stressed) of the water holding capacity of the substrate. Gas exchange, water status, fluorescence parameters, enzymatic antioxidants activity and dry matter production were evaluated. High CO2 concentration enhanced Açaí gas exchange (increasing CO2 assimilation), regardless of substrate water availability and temperature. However, high temperature and high vapor-pressure deficit reduced quantum yield and increased the minimum fluorescence and enzymatic antioxidants activity. With that, Açaí seedlings did not convert the additional assimilated carbon (due to higher CO2 concentration) into biomass, showing decreased total dry mass accumulation for RCP4.5 and RCP8.5 climate scenarios. Our results indicated that the positive impacts of increased CO2 concentration to gas exchange may not offset the negative impacts of increased air temperature and VPD to Açaí growth.