Bioaccumulation of selected macro- and microelements and their impact on antioxidant properties and accumulation of glucosinolates and phenolic acids in in vitro cultures of Nasturtium officinale (watercress) microshoots.

The study evaluated bioaccumulation capacity of macro- and microelements, their impact on the production of glucosinolates and phenolic acids and antioxidant properties in a microshoot culture model of Nasturtium officinale. Elements: calcium, chromium, copper, iron, lithium, magnesium, selenium and zinc were supplemented in different salt concentrations to culture media. Bioaccumulation of elements [mg/100 gDW] varied from 1.24 (Li,1 mg/l) to 498.62 (Cr,50 mg/l) and was dependent on the type of element and its concentration. The bioconcentration factor (BCF) ranged from 11.37 (Li,25 mg/l) to 4467.00 (Ca,1 mg/l). The total glucosinolate contents [mg/100gDW] varied from 108.11 (Cr,1 mg/l) to 172.90 (Ca,1 mg/l). The presence of four phenolic acids was confirmed in the microshoots. Their total contents [mg/100gDW] ranged from 19.35 (Mg,10 mg/l) to 139.21 (Fe,50 mg/l). The highest antioxidant activity [nM trolox/mgDW], as evaluated by CUPRAC and QUENCHER-CUPRAC methods, was equal to 55.50 (Cu,1 mg/l) and 161.10 (Li,5 mg/l), respectively. The results proved good correlations between all studied parameters.

Influence of irrigation conditions in the germination of plasma treated Nasturtium seeds.

Plasma treatments had emerged as a useful technique to improve seed germination. In this work we investigate the influence of different irrigation conditions and plasma treatments on the germination of nasturtium seeds. During plasma treatment, seeds experience a progressive weight loss as a function of treatment time that has been associated to water release, a process that is more pronounced after longer plasma treatment times. Seeds treated for short times (<30 s) are able to germinate more efficiently than untreated specimen under hydric stress (drought conditions), while plasma treatments for longer times (up to 300 s) impaired germination independently on irrigation conditions. Characterization analysis of plasma treated seeds by FTIR-ATR, SEM/EDX and XPS showed that plasma treatment affected the chemical state of pericarp while, simultaneously, induced a considerable increase in the seeds water uptake capacity. The decrease in germination efficiency found after plasma treatment for long times, or for short times under optimum irrigation conditions, has been attributed to that the excess of water accumulated in the pericarp hampers the diffusion up to the embryo of other agents like oxygen which are deemed essential for germination.

Impact of spiked concentrations of Cd, Pb, As and Zn in growth medium on elemental uptake of Nasturtium officinale (Watercress).

This study is aimed at investigating the impact of water quality on the uptake and distribution of three non-essential and toxic elements, namely, As, Cd and Pb in the watercress plant to assess for metal toxicity. The plant was hydroponically cultivated under greenhouse conditions, with the growth medium being spiked with varying concentrations of As, Cd and Pb. Plants that were harvested weekly for elemental analysis showed physiological and morphological symptoms of toxicity on exposure to high concentrations of Cd and Pb. Plants exposed to high concentrations of As did not survive and the threshold for As uptake in watercress was established at 5 ppm. Translocation factors were low in all cases as the toxic elements accumulated more in the roots of the plant than the edible leaves. The impact of Zn on the uptake of toxic elements was also evaluated and Zn was found to have an antagonistic effect on uptake of both Cd and Pb with no notable effect on uptake of As. The findings indicate that phytotoxicity or death of the watercress plant would prevent it from being a route of human exposure to high concentrations of As, Cd and Pb in the environment.

Chemiluminescent examination of abiotic oxidative stress of watercress.

Watercress (Nasturtium officinale) is an aquatic plant that readily bioaccumulates heavy metals that may be found in contaminated aquatic systems. Toxic effects of contaminants on the physiological processes cause changes in oxidase enzymatic activity in watercress, which can be measured with a luminometer. The luminometer uses the reaction produced when peroxidases break down hydrogen peroxide into water and an oxygen radical. The resulting oxyradical binds to and oxidizes phenolic groups, producing a measureable luminescent reaction. Nasturtium officinale plants were exposed to 3 different concentrations of heavy metals, including lead, nickel, copper, and manganese for 24 h, 48 h, and 72 h. Aquatic exposure to the 4 heavy metals caused a significant increase in oxidative enzyme production. Fluorometric and morphometric measurements were also conducted to compare plant stress with the oxidative enzyme analyses. Fluorometric measurements performed on plants stressed by exposure to heavy metals revealed no significant decreases in photosystem II efficiency. Morphometric measurements of root length showed decreased root growth resulting from exposures to Ni, Cu, and Mn.

Use of peroxyacetic acid as green chemical on yield and sensorial quality in Watercress (Nasturtium officinale R. Br.) under soilless culture.

The goal of this research was to evaluate the effect of different doses of peroxyacetic acid on the productivity of watercress (Nasturtium officinale R. Br.) cultivated hydroponically using a constant nutritive solution. Green chemistry in protected horticulture seeks compatibility with the environment through the creation of biodegradable byproducts. In hydroponics, appropriate doses of peroxyacetic mixtures deliver these byproducts while also oxygenating the roots. Watercress producers who recirculate the nutritive solution can use these mixtures in order to increase oxygenation in the hydroponic system. The experiment took place between August and December 2009, beginning with the planting of the watercress seeds and concluding with the completion of the sensory panels. A completely random design was used, including three treatments and four repetitions, with applications of 0, 20 and 40 mg L(-1) of the peroxyacetic mixture. Measured variables were growth (plant height, leaf length and stem diameter), yield (weight per plant and dry matter) and organoleptic quality (color and sensory panel). The application of 40 mg L(-1) of the peroxyacetic mixture had a greater effect on the growth and development of the plants, which reached an average height of 29.3 cm, stem diameter of 3.3 mm and leaf length of 7.6 cm, whereas the control group reached an average height of only 20.2 cm, stem diameter of 1.9 mm and leaf length of 5.7 cm. The application of the peroxyacetic mixtures resulted in an improvement in growth parameters as well as in yield. Individual weights achieved using the 40 mg L(-1) dose were 1.3 g plant(-1) in the control group and 3.4 g plant(-1) in the experimental group (62% yield increase). Sensory analysis revealed no differences in organoleptic quality.

Nickel accumulation and its effect on biomass, protein content and antioxidative enzymes in roots and leaves of watercress (Nasturtium officinale R. Br.).

In order to understand its response towards nickel stress, watercress (Nasturtium officinale R. Br.) was exposed to nickel (1-25 mg/L) for 1, 3, 5 and 7 days. The accumulation and translocation of nickel were determined and the influence of nickel on biomass, protein content and enzymatic antioxidants was examined for both roots and leaves. It was determined that N. officinale could accumulate appreciable amounts of Ni in both roots and leaves. Nickel accumulated particularly in the roots of plants. Biomass increased at low nickel concentrations but certain measurable change was not found at high concentrations. Under stress conditions the antioxidant enzymes were up-regulated compared to control. An increase in protein content and enzyme activities was observed at moderate exposure conditions followed by a decline at both roots and leaves. The maximum enzyme activities were observed at different exposure conditions. Our results showed that N. officinale had the capacity to overcome nickel-induced stress especially at moderate nickel exposure. Therefore, N. officinale may be used as a phytoremediator in moderately polluted aquatic ecosystems.

Effects of lead on the activities of antioxidant enzymes in watercress, Nasturtium officinale R. Br.

The aim of the present study is to evaluate the oxidative effects of lead with increased concentrations by the determination of antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and ascorbate peroxidase (AP)) and lipid peroxidation levels in the stem and leaves of watercress (Nasturtium officinale R. Br.) which was exposed to lead acetate, Pb (CH3COOH)2 regime with concentrations of 0, 50, 100, 200, 250, and 500 mg/L Pb in a hydroponic culture. After 14 days, accumulation of lipid peroxidation in stems and leaves and changes in activity of antioxidant enzymes were determined spectrophotometrically. The maximum accumulation was observed in the highest concentration group. In this group, lipid peroxidation levels were three times higher than the control group in the stem and leaves. The highest induction in SOD and GR activities were determined at 200 mg/L Pb group in stem, whereas CAT and AP activities were higher than other groups at the concentration of 250 and 100 mg/L Pb, respectively. The increase in CAT activity was found to be greater than GR, SOD, and AP activities in stems of watercress under Pb treatment. Both lead accumulation and antioxidant enzyme responses were higher in stems than in leaves. The results of the present study suggested that the induction in antioxidant responses could be occurring as an adaptive mechanism to the oxidative potential of lead accumulation.

Influence of nitrogen and sulfur on biomass production and carotenoid and glucosinolate concentrations in watercress (Nasturtium officinale R. Br.).

Watercress (Nasturtium officinale R. Br.) is a perennial herb rich in the secondary metabolites of glucosinolates and carotenoids. 2-phenethyl isothiocyanate, the predominate isothiocyanate hydrolysis product in watercress, can reduce carcinogen activation through inhibition of phase I enzymes and induction of phase II enzymes. Sulfur (S) and nitrogen (N) have been shown to influence concentrations of both glucosinolates and carotenoids in a variety of vegetable crops. Our research objectives were to determine how several levels of N and S fertility interact to affect watercress plant tissue biomass production, tissue C/N ratios, concentrations of plant pigments, and glucosinolate concentrations. Watercress was grown using nutrient solution culture under a three by three factorial arrangement, with three S (8, 16, and 32 mg/L) and three N (6, 56, and 106 mg/L) fertility concentrations. Watercress shoot tissue biomass, tissue %N, and tissue C/N ratios were influenced by N but were unaffected by changes in S concentrations or by the interaction of NxS. Tissue pigment concentrations of beta-carotene, lutein, 5,6-epoxylutein, neoxanthin, zeaxanthin, and the chlorophyll pigments responded to changes in N treatment concentrations but were unaffected by S concentrations or through N x S interactions. Watercress tissue concentrations of aromatic, indole, and total glucosinolate concentrations responded to changes in N treatments; whereas aliphatic, aromatic, and total glucosinolates responded to changes in S treatment concentrations. Individual glucosinolates of glucobrassicin, 4-methoxyglucobrassicin, and gluconasturriin responded to N fertility treatments, while gluconapin, glucobrassicin, and gluconasturiin responded to changes in S fertility concentrations. Increases in carotenoid and glucosinolate concentrations through fertility management would be expected to influence the nutritional value of watercress in human diets.

Influence of pH on lead uptake, chlorophyll and nitrogen content of Nasturtium officinale R. Br. and Mentha aquatica L.

In the present study, effects of pH (5.0, 7.0 and 9.0) and lead (1, 5, 10, 25, 50 and 100 microg mL(-1)) were investigated on uptake of lead, content of chlorophyll and nitrogen in Nasturtium officinale and Mentha aquatica. Total chlorophyll and nitrogen contents were adversely affected from Pb2+ concentrations dose dependently at each pH. The macrophytes were adversely affected by pH 5.0 or more than 9.0. After 12-days Pb2+ treatment, results showed that lead accumulation of macrophyte tissues was variable. According to the parts of the macrophytes, Pb2+ amounts were generally found at all tested pH levels and the metal concentrations for M. aquatica in the following order: root > stem > leaf and for N. officinale root > leaf > stem. Pb2+ concentrations in plant tissues (root, stem, leaf) in relation to pH were generally found for both macrophytes in following order: 7.0 > 9.0 > 5.0. Despite of the fact that high Pb2+ accumulation was observed in root tissues of the macrophytes, low metal accumulation was measured in the above-ground parts indicating low root-leaf translocation. The study indicated that uptake rate of Pb2+ and its toxicity on Chlorophyll and nitrogen contents in the macrophytes were dependent upon pH value of solutions.