Ecofisiologia de espécies amazônicas (Pilocarpus microphyllus e Euterpe oleracea) em cenários de mudanças climáticas

Abstract

The ecophysiological responses of many plant species in the face of predicted climate change are still unknown. An example are the Pilocarpus microphyllus and Euterpe oleracea species (popularly known as jaborandi and açaí, respectively). They are Amazonian species of great national and international commercial interest. They are Amazonian species of great national and international commercial interest. In this context, the research was divided into three chapters with the following objectives: to evaluate the effect of different environmental conditions on the ecophysiology of jaborandi seedlings, combining ranges of mean air temperature (T), vapor pressure deficit (DPV) and availability water on the substrate; evaluate the effect of three climate change scenarios on the ecophysiology of jaborandi seedlings; and in açaí seedlings. To achieve these objectives, a study was carried out with jaborandi seedlings in four environments (characterized as: cold and wet; hot and humid; hot and dry; and, cold and dry) and two studies (one with Pilocarpus microphyllus and the other with Euterpe oleracea) in three different climatic scenarios, characterized as: Current Amazon; RCP4.5 (current average temperature in the Amazon + 2.5 ° C and 538 ppm [CO2]) and RCP 8.5 (+ 4.5 ° C and 936 ppm [CO2]). Within each climatic scenario, two levels of irrigation were applied: seedlings kept at 90% (not stressed) and 40% (stressed) of the water holding capacity of the substrate. In the different experiments, variables were evaluated: growth, gas exchange, water status, chlorophyll fluorescence and enzymatic activity. The results obtained showed that jaborandi seedlings under water restriction reduced growth. In low temperature environments, in addition to growth, there was a reduction in quantum yield, an increase in minimum fluorescence and enzymatic activity. In addition, the largest accumulation of dry matter occurred in jaborandi seedlings submitted to higher temperature conditions. In climate change studies, both the jaborandi seedlings and the açai seedlings reduced growth as the atmospheric CO2 concentration increased. For both species, the RCP 8.5 scenario effect was the most limiting, mainly for seedlings under water stress. In this scenario, jaborandi and açaí seedlings with lower total dry mass production were observed, indicating that the predicted climate change scenarios have a negative impact on the future of these Amazonian species.