The increasing demand for healthy products rises the pressure on the chestnut production due to their nutritional qualities and beneficial health effects. Martaínha chestnut variety is most well-adapted with great economic importance due to its precocity and technological properties. The exogenous application of Silicon has an important role in agriculture because of improvement of plants nutrition. Nevertheless, the knowledge of impact of Silicon application in the production, sensory quality and chemical composition of chestnut fruits is limited. The application of Si in leaves (SL) and soil (SS) have important action on the prophylactic properties and the promotion of chestnuts health. Moreover, higher number of healthy fruits, caliber, fruits without rotten and tortrix infection and lower water loss in post-harvest chestnuts, in SL and SS samples, highlights the Si positive action. Additionally this study emphasizes some positive effects of Silicon on the chemical and sensory profile.

The protective effect of silicon (Si) against environmental stress has been observed in many crops. The objective of this work was to evaluate the impact of SiK® (potassium silicate) fertilization on the resilience capacity of chestnut plants growing under high air temperature conditions and their recovery capacity after a turnover to adequate temperatures. Castanea sativa plants were supplied with 0 mM, 5 mM, 7.5 mM, and 10 mM SiK® and exposed sequentially to 25 °C, 32 °C, and 25 °C for 1 month each. Data suggested that silicon are involved in increasing the heat tolerance of chestnut plants by reducing the oxidative damage and improving the antioxidant enzymes and metabolites. Under heat stress (32 °C), there was an increase in the catalase, ascorbate peroxidase, and peroxidase activities, as well as in the phenol content of supplemented plants, which consequently reduced the electrolyte leakage, lipid peroxidation, and hydrogen peroxide content. Additionally, a lower proline content was measured inside the leaves’ tissues of Si-treated plants. Besides the resilience against heat stress, after exposure to 32 °C, the recovery was also quick.

Silicon is an essential mineral nutrient, that plays a crucial role in the metabolic, biochemical, and functional mechanisms of many crops under environmental stress. In the current study, we evaluated the effect of SiK^® fertilization on the biochemical defense response in plants exposed to water stress. Castanea sativa plants were fertilized with different concentrations of potassium silicate (0, 5, 7.5, and 10 mM of SiK^®) and exposed to a non-irrigation phase and an irrigation phase. The results indicate that silicon promoted the synthesis of soluble proteins and decreased the proline content and the oxidative stress (reduced electrolyte leakage, lipid peroxidation, and hydrogen peroxide accumulation) in tissues, due to an increase in ascorbate peroxidase, catalase, and peroxidase activity, which was accompanied by the rise in total phenol compounds and the number of thiols under drought conditions. This study suggests that exogenous Si applications have a protective role in chestnut plants under water deficit by increasing their resilience to this abiotic stress

The objective of this study was to identify and analyze the elements of inquiry teaching included in activities produced by undergraduate students in initial training at a Portuguese university. This is a qualitative descriptive study in which eleven students from the Master's program in Basic Education participated. The students participated in a course on inquiry teaching and at the end of the course they produced investigative activities that were analyzed in this study. The objective was to observe in the activities the component elements of teaching by inquiry and thus infer the difficulties encountered by undergraduate students when contemplating these elements in the activities. The results show that the difficulties encountered by undergraduate students in the preparation of research activities are concentrated in the insertion of research elements related to the elaboration and coherence of the problem presented, the recording and analysis of data and the elaboration of a conclusion.