Dissertação
Selênio e silício como amenizadores da toxicidade do cádmio em plantas de Pfaffia glomerata(Spreng.) Pedersen
Fecha
2016-06-17Autor
Pereira, Aline Soares
Institución
Resumen
The soil contamination with heavy metals such
as cadmium ( causes damage to many
plants . Among the alternatives sought to solve the problems with this toxic metal s in the
growth of plants is the use of alleviators, ie elements considered beneficial , that when
used in low concentrations may alleviate the damaging effects of toxic elements. In this
sense, the present study aimed to evaluate the capacity of selenium (Se) and silicon (Si)
to reduce the absorption and Cd toxicity in P faffia glomerata plants in hydroponic system .
The P. glomerata plants were propagated in vitro and after acclimation transferred to
hydroponic nutrient solution , where were added the follow ing combinations of Se (0 to 2.5
mM), Si (0 and 2.5 mM) and Cd (0 and 50 µ M) (T1: 0 µ M Cd + 0 mM Se and Si, T2: 0 µM
Cd + 2 5 mM Se; T3: 0 µM Cd + 2 5 mM Si; T4: 50 µM Cd; T5: 50 µM Cd + 2 5 mM Se, T6: 50 µM
Cd + 2 5 mM Si Data were submitted to analysis of variance and means were compared
by the Scott Knott test at 5% probability of error. After exposure to different treatments (14
days)days), the plants were collected and analyzed for morphophysiological (fresh and dry
weight, plant height, length and densit y of roots, leaf area, leaves number and
photosynthetic parameters) and biochemical parameters (antioxidant enzymes,
photosynthetic pigments content, hydrogen peroxide content, and damage to membrane
lipids). The presence of Cd in nutrient solution promote d reduction in leaf area, biomass ,
morphological parameters of the root system and photosynthetic parameters, except for
the shoot dry weight, leaf number and plant height. In general, in the treatments containing
Se or Si with Cd, plants showed positive r esponses to the fresh weight of shoot and root s ,
root dry weight, length, diameter, volume and branching roots, leaf area, photosynthetic
rate, internal CO 2 concentration, transpiration rate, water use efficiency and carboxylation
of rubisco efficiency, th us showing that they can alleviate the Cd toxicity. The potential of
Se and Si to ameliorate the Cd toxicity can also be seen in the contents of chlorophylls,
carotenoids and H 2 O 2 , and in the superoxide dismutase (SOD) and guaiacol peroxidase
(POD) activit y. F or lipid peroxidation Si was more effective than Se in ameliorate the Cd
toxicity. Thus, t he potential o f the Si and Se to ameliorate the Cd toxicity can be used to
increase the productivity and quality of medicinal plants in an environmentally proper
manner