The goal of the study was to investigate the effects of exogenous selenium (Se) on the tolerance of faba bean plants to lead (Pb) stress under P-deficient conditions. The bean plants were grown for 2 weeks on Hoagland solution supplied with Pb (0, 50 lM) and Se (0, 1.5, or 6 lM), separately or simultaneously. It was shown that Pb did not affect shoot growth but caused major damage in the leaves, which was accompanied by Pb accumulation in these tissues. The exposure of the shoots to Pb led to significant changes in the biochemical parameters: the MDA content, glutathione peroxidase (GSH-Px), guaiacol peroxidase (GPOX), and catalase (CAT) activity increased. Furthermore, Pb intensified O 2•-and H 2 O 2 production. Both the Se concentrations used increased the chlorophyll b, chlorophyll a?b, and carotenoid content in the faba bean plants. Selenite also generally enhanced CAT, GPOX, and GSH-Px activities and the T-SH level. Our results imply that the degree of disturbances caused by Pb could be partially ameliorated by Se supplementation. Selenite at a lower dose alleviated Pb toxicity by decreased H 2 O 2 and O 2•-production and decreased the GSH-Px, GPOX, and CAT activities. The beneficial effect of the higher selenite concentration could be related to reduction of lipid peroxidation in the shoots of the Pb-treated plants. However, the effect of Se on the Pb-stressed plants greatly depended on the selenite dose in the nutrient solution.

The activities of antioxidative enzymes, i.e. superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX), in the leaves and roots of L. plants exposed to abiotic (methyl jasmonate, MJ, or/and copper, Cu) and biotic () factors were examined. The contribution of MJ as a signal molecule in the defense mechanism against abiotic and biotic stresses was studied. All plants were cultivated hydroponically and divided into three groups: not treated by abiotic factors (control), treated by MJ only (MJ) and by MJ and Cu (MJ + Cu) and in each group half of the plants were exposed to attack. The enzymatic activities of SOD, CAT, APX, and GPX in the leaves were higher in the insect-treated than non-insect-treated control plants, but lower in both MJ + Cu- or MJ- and insect-treated plants. In the roots, the enzyme activities were elevated in all insect-treated plants with the highest rise in MJ + Cu, in comparison with the MJ-treated plants. The results showed that MJ and MJ + Cu were efficient in reducing the activity of the antioxidative enzymes in the leaves under the insect influence by elevating enzyme activity in the roots.

In this work, the effect of lead on sunflower seedlings with two root system types: primary -formed from embryonic tissues and adventitious -originating from hypocotyl after cutting off primary roots was investigated. The seedlings were subjected to Pb(NO 3 ) 2 in doses: 0, 0.5, 2.5, 5 and 20 mg(Pb) dm -3 for a week. Lead accumulation, seedling length and mass as well as selected parameters representative of oxidative damage (malondialdehyde) and protection (superoxide dismutase and glutathione) were used to compare stress response of plants. The comparison showed significant differences between plants with different root systems in almost all the parameters and the plants with adventitious root were more tolerant to lead.

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The aim of the present study was to analyse commercially available compounds containing nanoparticles in the form of Ag, Cu, and Ag sulphate colloids applied in agriculture. The compounds were analysed with TEM and FTIR spectroscopy, i.e., methods that can complement the commonly used research techniques such as EDX or Raman spectroscopy. The results of the microscopic examinations evidenced the presence of single spherical agglomerates (small granules) of the nanoparticle-containing products. Infrared spectroscopy revealed the presence of bands characteristic of vibrations that can be assigned to nanoparticle-X interactions, where X = S, C, or O in aqueous colloid solutions of the analysed samples. Additionally, bands characteristic for C-H stretching vibrations (probably associated with vibrations of the -CH 2 and -CH 3 groups) were observed as bands originating from compounds used as the carriers of the analysed systems. In the case of Ag sulphate, the most distinct band with a maximum at 2,863 cm -1 , which is characteristic of SH···Ag vibrations, can be observed, and its intensity may be associated with the nanostructure composition of the formulation, which is more diverse than that in the other two compounds.