ABSTRACT Despite the importance given to Silicon in the relief of stress in cultivated plants, there are no experimental studies on abiotic stresses that address this function of Si in plants under natural environments, aiming to identify responses that would indicate acclimatisation to the conditions at their place of origin. The goal of this study was to answer the following questions: 1) Does abiotic stress increase Si absorption? 2) Does the presence of Si stimulate biomass production in natural environments? and 3) Do plants from different environments display differences in Si absorption? To do so, Eugenia punicifolia was selected as a study species since it has a wide distribution, occurring in three different physiognomies: Coastal Savanna, Dense Deciduous Shrubland and Seasonal Deciduous Forest. The Si absorption varied depending on the temperature and this was directly related to increases in dry matter production in E. punicifolia plants, suggesting that this may be a relief mechanism for temperature and water stresses. Differences in the response to stress conditions may be a result of the phenotypic plasticity which occurs in E. punicifolia and suggests that plasticity could be a useful asset in the use of Si fertilizer for crops. origin questions 1 2 3 so distribution physiognomies Savanna Forest E crops

RESUMO Considerando a importância do Silício (Si) para as plantas, nas últimas décadas muitos estudos avaliaram a capacidade do elemento em aliviar o estresse abiótico em diferentes espécies, a maioria delas de interesse agrícola. Para todas as espécies, o Si oferece uma gama de benefícios às plantas na redução dos efeitos do estresse biótico e abiótico, estando especialmente associado a aumentos na biomassa das plantas. No entanto, quando realizamos uma revisão quantitativa sistemática de estudos que relacionam o Si ao alívio do estresse abiótico em plantas, demonstramos que há uma redução dos efeitos do Si ao longo do tempo e que os efeitos do silício foram menores nos estudos mais recentes. Além disso, descobrimos que plantas sob diferentes tipos de estresse tiveram respostas semelhantes ao Si, sugerindo que os mecanismos de alívio do estresse abiótico nas plantas podem ser comuns entre as condições de estresse hídrico, salinidade e metais pesados – os principais estresses ambientais estudados na literatura. Nosso estudo pode direcionar estudos futuros, que não devem se limitar a simplesmente avaliar a existência de quaisquer efeitos de alívio de estresse do Si, mas também compreender a variação que existe nesses mecanismos e que depende do tipo de estresse e dos fatores envolvidos na redução desses efeitos.

ABSTRACT Considering the importance of Silicon (Si) for plants, many studies have focused to evaluate the ability of the element to alleviate abiotic stress in different species, mainly of agricultural interest. For all species, Si offers a range of benefits in reducing the effects of biotic and abiotic stress, being especially associated with increases in plant biomass. However, after performed a systematic quantitative review of studies linking Si to the relief of abiotic stress in plants, it was demonstrated that there is a reduction in the effects of Si over time and that the effects of Si were smaller in recent studies. Furthermore, was found that plants under different types of stress had similar responses to Si, suggesting that abiotic stress relief mechanisms in plants may be common among conditions of water stress, salinity, and heavy metals – the main environmental stresses studied in the literature. This study can guide future research, which should not be limited to simply evaluating the existence of any Si stress-relieving effects, but also to understand the variation that exists in these mechanisms and considered that they depend on the type of stress and the factors involved in reducing these effects.