Dissertação
Efeitos da adição de alumínio, silício e selênio na fisiologia e bioquímica de Schinus terebinthifolius Raddi
Fecha
2019-03-11Autor
Mattos, Jéssica Patrícia Oliveira de
Institución
Resumen
Brazilian Southern region presents acidic soils, being many of them classified as aluminum and
alicytes, highlighting aluminum (Al) high levels occurrence. When in acid soils, the element is
present in a trivalent form (Al
+3
), which is toxic for vegetal organisms. Studies already
demonstrated the silicon (Si) and selenium (Se) efficacy as damage attenuators caused by
phytotoxic elements. In this sense, our objective was to evaluate the resistance of the species to
Al and Si and Se effect on Al toxicity in plants of Schinus terebinthifolius Raddi under
hydroponic conditions. This study was conducted in greenhouse and in Plant Biochemistry
Laboratory at Biology Department, Federal University of Santa Maria, RS. S. terebinthifolius
plants were propagated via seeds in commercial substrate and later transferred to hydroponic
culture in nutrient solution, where Al, Si and Se concentrations in mM were added as follows:
Treatment 1: 0 Al + 0 Se and Si; Treatment 2: 2.5 Si; Treatment 3: 0 Al + 0.0025 Se; Treatment
4: 1.85 Al + 0 Se and Si; Treatment 5: 1.85 Al + 2.5 Si; Treatment 6: 1.85 Al + 0.0025 Se;
Treatment 7: 3.71 Al + 0 Se and Si; Treatment 8: 3.71 Al + 2.5 Si; Treatment 9: 3.71 Al +
0.0025 Se). Following 21 days exposure to different treatments, under hydroponic cultivation
were evaluated physiological variables (fresh and dry biomass, plant height, root system
morphological variables, leaf area and photosynthetic variables) as well as biochemical
(antioxidant enzymes, lipid peroxidation, and hydrogen peroxide content, ascorbic acid, non-
protein thiols and photosynthetic pigments). Considering physiological variables, it was
observed that Al is phytotoxic to this species at concentrations of 1.85 mM and 3.71 mM Al
leading to significant reductions in shoot and root development. While Se did not mitigate
damages caused by Al exposure, Si was able to alleviate only the damages caused by lowest Al
concentrations (1.85 mM). Regarding biochemical variables, both Si and Se presented
beneficial effects in Al-stress alleviation, mainly through antioxidant system activation and
reduction of lipid peroxidation damages. In this way it can be concluded that the species has its
performance negatively affected by Al presence, both physiologically and biochemically.
However, Si was efficient in reducing physiological damage caused by Al, especially when Al
concentrations were lower, whereas Se did not present this effect. Biochemically it has been
noted that both Si and Se were capable of alleviating damage caused by Al through antioxidant
system maintenance. Therefore, our results allow us to conclude that Si and Se elements were
efficient in alleviating physiological and biochemical damages caused by aluminum in S.
terebinthifolius plants.