O caráter acumulador de alumínio pode ser fisiologicamente benéfico para Rubiaceas nativas?

Abstract

Acid soils can be present in both Cerrado and Mata Atlântica, sometimes, with high aluminum (Al) saturation. In regions with seasonal climates and where the vegetation is an ecotone of both biomes, such as Belo Horizonte, the variation of water availability, of temperature and the presence of Al can be key factors for the understanding of the vegetal species' dynamics. Despite Al to be toxic for the vast majority of species, some families accumulate and benefit physiologically from its presence, being the Rubiaceae family an example. Curiously, within the family, there are species that are able to accumulate Al and others that don’t have this feature. In that regard, this work proposed to answer the following questions: 1) The accumulation character of aluminum is a benefic factor for the plants of Rubiaceae’s family under dry conditions? How can the temperature impact the response of plants that are or aren’t accumulators of Rubiaceae’s family? What the physiologicals parameters can be affected by the accumulated or not of Al in the different climate seasons. For this, six species of Rubiaceae were evaluated, three accumulators and three non-accumulators. The experiment was performed under field conditions, during dry and rainy seasons. We evaluated the Relative water content (RWC), pigments content,thermotolerance of the photosystem II, potential quantum yield (Fv/Fm) and the maximum electron transport rate (ETRmax), as well the soil water content (SWC). The results show that the non-accumulator species of Al have a high thermotolerance (Figure 11 and 12) and pigments content (6 to 9), indicating that Al can induce negative effects in Rubiaceae. Considering the different seasons, the SWC, the RWC and the thermotolerance increased during the rainy season, except for the thermotolerance of T50 in the accumulators. The pigment's content was lower in the rainy season for the accumulator’s species. The results indicate the importance of characterizing the ecophysiological responses in families classified as Al-accumulators and reinforces the need to know more from the physiology of native species, especially when considering the events coming from climate change, where water and thermal stresses will be more frequent.