The Influence of Copper and Zinc on Photosynthesis and Phenolic Levels in Basil (Ocimum basilicum L.), Borage (Borago officinalis L.), Common Nettle (Urtica dioica L.) and Peppermint (Mentha piperita L.).

This work is aimed at relationships which govern zinc and copper uptake by four popular medicinal herbs: basil (Ocimum basilicum L.), borage (Borago officinalis L.), common nettle (Urtica dioica L.) and peppermint (Mentha piperita L.). They are often grown in soils with significant copper or zinc levels. Herbs were cultivated by a pot method in controlled conditions. Manganese, iron, copper and zinc concentrations were determined by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry. The efficiency of photosynthesis was estimated by measuring the chlorophyll content, water use efficiency, net photosynthesis, intercellular CO2, stomatal conductance, and transpiration rate. Phenolic compounds were determined by the Folin-Ciocalteu method. Analysis of variance showed that herbs grown in soil treated with copper exhibited a lower iron content in roots, while manganese behaved in the opposite way. The only exception was borage, where a decrease in the manganese content in roots was observed. Both copper and zinc supplementations increased the total content of phenolics, while the highest increases were observed for common nettle and basil. Peppermint and borage responded less to supplementation. In the majority of samples, zinc and copper did not significantly affect the photosynthesis. Herbal extracts from common nettle and basil had unique antioxidant properties and may be good free radical scavengers.

Antioxidant Activity and Photosynthesis Efficiency in Melissa officinalis Subjected to Heavy Metals Stress.

The aim of this study was to assess influence of cadmium and zinc treatments on antioxidant activity combined with the photosynthesis efficiency in a popular herb lemon balm (Melissa officinalis L.). Plants were grown under greenhouse conditions by the pot method. The Mn, Cu, Cd, and Zn contents in soil and plants were measured by HR-CS FAAS. The activity of net photosynthesis, stomatal conductance, transpiration rate, intercellular CO2, and index of chlorophyll in leaves were determined for all investigated species. Reduction of the net photosynthesis was observed for cultivations subjected to either Zn or Cd treatments. Phenolic contents were determined by the chemical Folin-Ciocalteu method, while enhanced voltammetric analysis was applied to assess the antioxidant properties of plant extracts. Both of these approaches yielded similar results. Herbal extracts had exceptional antioxidant capacities and were good scavengers of free radicals and reactive oxygen species. Structural similarity of cadmium and zinc facilitated their mutual structural exchange and prompted substantial expansion of phenolics under the mixed Zn and Cd treatments.

The Impact of Soil pH on Heavy Metals Uptake and Photosynthesis Efficiency in Melissa officinalis, Taraxacum officinalis, Ocimum basilicum.

Herbs used in medicine should be grown under controlled and standardized conditions. Agricultural practices often induce changes to soil pH, which may affect migration of heavy metals in the environment, their accumulation in plant tissues and the concentration of medicinal ingredients. The aim of this work was to assess the influence of various soil pH on the biological parameters and uptake of manganese, copper and zinc by basil, dandelion and lemon balm. The soil analysis covered pH, organic matter content, bioavailable and total forms of investigated metals in soil. In plants cultivated in soil at pH covering the range 4.7-8.5 the concentrations of Mn, Cu and Zn were analyzed. Their mobility and availability were assessed by bioaccumulation factors, translocation factors and transfer coefficients. The seed germination and subsequent herbs growth were strongly dependent on soil pH for all investigated plant species. Photosynthetic efficiency at different pHs was positively correlated with uptake of Cu and Mn while Zn behaved in a more random way.

Hysteresis of heavy metals uptake induced in Taraxacum officinale by thiuram.

Dandelion (Taraxacum officinale) yields active substances frequently used in herbal medicinal preparations. Its plantations are exposed to fungal plagues which pose a threat to herbal crops. The aim of this study was to evaluate the long time effects of a fungicide thiuram on dandelion growth and photosynthesis. Additionally, the manganese, iron, copper, zinc, cadmium, and lead uptake and transport were also investigated. Plants were cultivated under greenhouse conditions by the pot method in a universal flowering soil. The elements content in soil and plants were determined by the HR-CS FAAS spectrometer. Thiuram concentrations were established by the HPLC. Those analyses showed that almost 80% of thiuram decomposed within two weeks of its application. The photosynthesis indicators suggested, that plants were in good conditions and the fungicide supplementation facilitated plant growth. The latter could be prompted by thiuram acting as a sulfur rich chemical micro fertilizer. The hypothesis, that thiuram significantly affects heavy metals interactions in dandelion was proved by the one-way analysis of variance. Notable, metals uptake did not completely recover after fungicide decomposition for all investigated elements except iron We suggest to define this chemically induced, time-dependent heavy metals migrations in the soil-plant system as hysteresis of heavy metals uptake.

Combined cadmium-zinc interactions alter manganese, lead, copper uptake by Melissa officinalis.

Farmland soil typical for the Polish rural environment was used in pot experiment to estimate the impact of cadmium and zinc on the manganese, lead and copper uptake by lemon balm (Melissa officinalis L). Bioavailable and total forms of investigated metals in soil and metal concentrations in plants were determined by atomic absorption spectrometry. The plant photosynthesis indicators were also examined. Intensification of photosynthesis upon the high zinc and cadmium soil supplementation was observed. This effect was not detected at low metal concentrations. ANOVA proved that cadmium and zinc treatments influenced manganese, lead and copper transfer from soil and their concentration in plants. Zinc uptake and accumulation in either roots or above-ground parts in plant was inversely proportional to cadmium concentration in soil. Manganese concentration in roots decreased upon the soil supplementation with either zinc or cadmium. It suggests that the latter ions are transported via symplastic pathways and compete with manganese for similar transporters. The opposite situation was observed for lead and copper. Soil supplementation with cadmium and zinc affects manganese, lead and copper concentrations and photosynthesis intensity in lemon balm plant. The following combined interactions in either normal or stress conditions are important indicators of the migration pathways.

Associated Effects of Cadmium and Copper Alter the Heavy Metals Uptake by Melissa Officinalis.

Lemon balm (Melissa officinalis) is a popular herb widely used in medicine. It is often cultivated in soils with substantial heavy metal content. Here we investigate the associated effects of cadmium and copper on the plant growth parameters augmented by the manganese, zinc, and lead uptake indicators. The concentration of all elements in soil and plants was determined by the HR-CS FAAS with the ContrAA 300 Analytik Jena spectrometer. Bioavailable and total forms calculated for all examined metals were augmented by the soil analyses. The index of chlorophyll content in leaves, the activity of net photosynthesis, stomatal conductance, transpiration rate, and intercellular concentration of CO2 were also investigated. Either Cd or Cu acting alone at high concentrations in soil are toxic to plants as indicated by chlorophyll indices and gas exchange parameters. Surprisingly, this effect was not observed when both metals were administered together. The sole cadmium or copper supplementations hampered the plant's growth, lowered the leaf area, and altered the plant's stem elongation. Analysis of variance showed that cadmium and copper treatments of lemon balm significantly influenced manganese, lead, and zinc concentration in roots and above ground parts.

Influence of Digestion Procedure and Residual Carbon on Manganese, Copper, and Zinc Determination in Herbal Matrices by Atomic Absorption Spectrometry.

Mineralization to the complete oxidation of sample carbon component does not always assure the best analyte recovery. Particular attention should be paid to the presence of silicon in the investigated plant sample and especially in the certified reference material for which Si content is scarcely given by the providers. During mineralization without addition of the hydrofluoric acid, the residual carbon may block silica surfaces and increase availability of an analyte for its spectral determination in the solution. This issue is of particular relevance because standard protocols for digestion of plant matrices often do not support hydrofluoric acid addition. Several procedures recommended for decomposition of herbal plants were applied for the respective certified reference material and examined in detail. Manganese, copper, and zinc contents were analyzed in all samples by the flame atomic absorption spectrometry. Additionally, the residual carbon was determined in all mineralizates. Silicon content was analyzed by the X-ray fluorescence method. The best recoveries were observed for samples characterized by relatively high residual carbon.

Heavy Metal Uptake by Herbs. V. Metal Accumulation and Physiological Effects Induced by Thiuram in Ocimum basilicum L.

Basil (Ocimum basilicum L.) is extensively cultivated as either an important spice and food additive or a source of essential oil crucial for the production of natural phenylpropanoids and terpenoids. It is frequently attacked by fungal diseases. The aim of the study was to estimate the impact of thiuram contact time on the uptake of manganese, cobalt, nickel, copper, zinc, cadmium, and lead by Ocimum basilicum L. The relevant plant physiological parameters were also investigated. Two farmland soils typical for the Polish rural environment were used. Studies involved soil analyses, bioavailable, and total forms for all investigated metals, chlorophyll content, and gas exchange. Atomic absorption spectrometry was used to determine concentration of all elements. Analysis of variance proved hypothesis that thiuram treatment of basil significantly influences metal transfer from soil and their concentration in roots and aboveground parts. This effect is mostly visible on the 14th day after the fungicide administration. Thiuram modifies mycoflora in the rhizosphere zone and subsequently affects either metal uptake from the soil environment or their further migration within the basil plant. Notable, those changes are more evident for basil planted in mineral soil as compared to organic soil with higher buffering capacity.

Heavy Metal Uptake by Herbs. IV. Influence of Soil pH on the Content of Heavy Metals in Valeriana officinalis L.

The aim of the study was to estimate the influence of soil pH on the uptake of copper, zinc, and manganese by Valeriana officinalis. Preliminary studies involved soil analyses to determine acidity, organic matter content, and copper, zinc, and manganese total and bioavailable forms. The study involved atomic absorption spectrometry to determine the concentration of the elements, and mineral soil of pH = 5.1 was used in the study, as being typical for central Poland. The copper, zinc, and manganese contents were determined in plants grown in soils which had been modified to cover a wide range of pH values 3÷13. The intensity of germination was strongly pH dependent with the highest yield obtained in original, unmodified soil. Surprisingly, high soil alkalinity stimulated copper and manganese uptake while at the same time resulting in a decrease in zinc content.