Accumulation Capacity of Nickel and Zinc in Yerba Mate Cultivated in Soils with Contrasting Parent Materials

Yerba mate (Ilex paraguariensis St. Hill.) has shown a relatively high capacity for micronutrient absorption and could be a candidate for biofortification and combating a lack of micronutrients. To further evaluate the accumulation capacity of Ni and Zn, yerba mate clonal seedlings were grown in containers under five rates of Ni or Zn (0, 0.5, 2, 10, and 40 mg kg-1) with three soils originating from different parent material (basalt, rhyodacite, and sandstone). After 10 months, plants were harvested, divided into component parts (leaves, branches, and roots), and evaluated for 12 elements. The use of Zn and Ni enhanced seedling growth under rhyodacite- and sandstone-derived soils at the first application rate. Application of Zn and Ni resulted in linear increases based on Mehlich I extractions; recovery of Ni was smaller than Zn. Root Ni concentration increased from approximately 20 to 1000 mg kg-1 in rhyodacite-derived soil and from 20 to 400 mg kg-1 in basalt- and sandstone-derived soils; respective increases in leaf tissue were ~ 3 to 15 mg kg-1 and 3 to 10 mg kg-1. For Zn, the maximum obtained values were close to 2000, 1000, and 800 mg kg-1 for roots, leaves, and branches for rhyodacite-derived soils, respectively. Corresponding values for basalt- and sandstone-derived soils were 500, 400, and 300 mg kg-1, respectively. Although yerba mate is not a hyperaccumulator, this species has a relatively high capacity to accumulate Ni and Zn in young tissue with the highest accumulation occurring in roots. Yerba mate showed high potential to be used in biofortification programs for Zn.

Multi-elemental Analysis and Health Risk Assessment of Commercial Yerba Mate from Brazil

Consumption of yerba mate occurs mostly in the form of hot infusion (chimarrão). Water solubility of elements found in commercialized yerba mate is needed to establish nutritional value and risks associated with potentially toxic elements. In this study, yerba mate products marketed in three Brazilian states (Paraná, Santa Catarina, and Rio Grande do Sul) for chimarrão were analyzed. Total (dry product) and hot water-soluble concentrations of Al, As, B, Ba, Ca, Cd, Co, Cs, Cu, Fe, K, Li, Mg, Mn, Mo, Ni, P, Pb, Rb, S, Se, Sr, Ti, V, and Zn were determined by inductively coupled plasma mass spectroscopy (ICP-MS). Total concentrations of the ten top elements followed the order of K>Ca>Mg>Mn>P>S>Al>Fe>Ba>Zn. The most soluble elements were B, Cs, Ni, Rb, and K, with values greater than 80%. The lowest water-soluble elements were V, Fe, and Ti (values <10%), followed by Ba, Cd, Al, As, Sr, Ca, and Pb with solubility between 10 and 20%. Although total Cd levels in yerba mate products were often above those permitted by South America legislation, estimated daily consumption intake indicated no risk associated with the chimarrão beverage. Manganese was the micronutrient with the highest total and soluble levels in yerba mate, which surpassed recommended daily intake values when considering a consumption amount of 50 g day^-1 of yerba mate as chimarrão. The consumption of yerba mate is safe and contributes to intake of nutrients. The Cd and Pb reference values of yerba mate products sold in South America should be revised.

A new hypothesis for the origin of Amazonian Dark Earths

Amazonian Dark Earths (ADEs) are unusually fertile soils characterised by elevated concentrations of microscopic charcoal particles, which confer their distinctive colouration. Frequent occurrences of pre-Columbian artefacts at ADE sites led to their ubiquitous classification as Anthrosols (soils of anthropic origin). However, it remains unclear how indigenous peoples created areas of high fertility in one of the most nutrient-impoverished environments on Earth. Here, we report new data from a well-studied ADE site in the Brazilian Amazon, which compel us to reconsider its anthropic origin. The amounts of phosphorus and calcium-two of the least abundant macronutrients in the region-are orders of magnitude higher in ADE profiles than in the surrounding soil. The elevated levels of phosphorus and calcium, which are often interpreted as evidence of human activity at other sites, correlate spatially with trace elements that indicate exogenous mineral sources rather than in situ deposition. Stable isotope ratios of neodymium, strontium, and radiocarbon activity of microcharcoal particles also indicate exogenous inputs from alluvial deposition of carbon and mineral elements to ADE profiles,  beginning several thousands of years before the earliest evidence of soil management for plant cultivation in the region. Our data suggest that indigenous peoples harnessed natural processes of landscape formation, which led to the unique properties of ADEs, but were not responsible for their genesis. If corroborated elsewhere, this hypothesis would transform our understanding of human influence in Amazonia, opening new frontiers for the sustainable use of tropical landscapes going forward.

Manganese hyperaccumulation capacity of Ilex paraguariensis A. St. Hil. and occurrence of interveinal chlorosis induced by transient toxicity

Manganese (Mn) toxicity is common in plants grown on very acid soils. However, some plants species that grow in this condition can take up high amounts of Mn and are referred to as hyperaccumulating species. In this study, we evaluated the capacity of Ilex paraguariensis to accumulate Mn and the effect of excessive concentrations on plant growth and nutrition. For this, a container experiment was conducted using soils from different parent materials (basalt and sandstone), with and without liming, and at six doses of applied Mn (0, 30, 90, 270, 540 and 1,080 mg kg^-1). Clonal plants grown for 203 days were harvested to evaluate yield, and leaf tissue samples were evaluated for Mn and other elements. Without liming and with high Mn doses, leaf Mn concentrations reached 13,452 and 12,127 mg kg^-1 in sandstone and basalt soils, respectively; concentrations in excess of 10,000 mg kg^-1 are characteristic of hyperaccumulating plants. Liming reduced these values to 7203 and 8030 mg kg^-1. More plant growth accompanied increased Mn leaf concentrations, with a growth reduction noted at the highest dose in unlimed soils. Elemental distribution showed Mn presence in the mesophyll, primarily in vascular bundles, without high Mn precipitates. Interveinal chlorosis of young leaves associated with high Mn concentration and lower Fe concentrations was observed, especially in sandstone soil without liming. However, the occurrence of this symptom was not associated with decreased plant growth.

Elemental composition of yerba mate (Ilex paraguariensis A.St.-Hil.) under low input systems of southern Brazil

Elemental composition of food can be used to determine nutritional potential as well as guiding legislation for establishing maximum acceptable limits (MAL) of metals in consumption products. This study aimed to determine the elemental background levels of yerba mate (Ilex paraguariensis A.St.-Hil.) under varied geologic formations in southern Brazil. Mature leaves were randomly collected from four wild-grown plants at thirty native sites in three states and analyzed for 32 elements. Since yerba mate is not washed to obtain the final product, leaves were analyzed with and without washing to assess foliar deposition. Concentration values of As, Ag, Be, Cs, Cr, Li, Se, Tl, U, and V were near detection limits, indicating low potential as a source and/or toxicity to the consumer. Washing decreased concentrations of Fe, Ti, As, Mo, Li, V, and Pb, suggesting atmospheric contributions/dust deposition. Concentrations of Mn (very high), Zn (high), and Ni (high) demonstrated that leaves could be an important source of these elements. Soil parent material affected elemental composition with basalt providing higher concentrations of Mn, P, and Co while Rhyodacite provided higher concentrations of K and Na. All samples exhibited Pb values below the MAL of 0.6 mg kg^-1, but 23% of washed leaves and 20% of unwashed leaves had Cd concentrations close to or above the MAL value of 0.4 mg kg^-1. Study results indicated that Cd MAL values for yerba mate in southern Brazil should be reassessed.

SOIL CHEMICAL ATTRIBUTES AND THEIR INFLUENCE ON ELEMENTAL COMPOSITION OF YERBA MATE LEAVES

Yerba mate (Ilex paraguariensis St. Hil.) is a raw material used in making a beverage whose chemical composition can be altered by the growing environment and the management adopted during its cultivation. Thus, it is essential that scientific studies are undertaken to understand the chemical composition of yerba mate related to its growing environment. The aim of this work was to determine the elemental composition in the leaves of yerba mate from native cultivations that had never received fertilization and liming, from the Southern Region of the state of Paraná, Brazil. Soil and leaf samples were collected at 11 sites located in the municipalities of São Mateus do Sul, Mallet, São João do Triunfo, and Lapa. Leaf analyzes were performed in an Optical Emission Spectrometer with Inductively Coupled Plasma. The mean concentrations observed (mg kg-1), in decreasing order, were: Ca – 7880; K – 7310; Mn – 2418; - Mg – 820; P – 720; Al – 474; Fe – 231; B – 78; Zn – 62; Ba - 62; Cu – 8.9; Ni – 5.6; Cr – 0.82; V – 0.53; Co – 0.17. The Mn concentrations were directly correlated with Al3+ saturation and inversely correlated with base saturation, pH, and the available Ca2+, demonstrating that changes among these soil components can significantly modify the Mn concentrations in the yerba mate leaves. The high concentrations of Mn and Al in the leaves of yerba mate demonstrate the adaptation of this species to acidic soils with high saturation of Al3+.

DINÂMICA DE CRESCIMENTO E PRODUTIVIDADE DE FORRAGEM DE Trachypogonplumosus SOB NÍVEIS DE CORREÇÃO DA FERTILIDADE DO SOLO E IDADES DE REBROTA

Resumo Avaliaram-se os efeitos de níveis de correção da fertilidade do solo (testemunha, calagem, adubação e calagem + adubação) e da idade de rebrota (21, 28, 35, 42, 49, 56, 63, 70, 77 e 84 dias) sobre a dinâmica de crescimento e rendimento de forragem de Trachypogon plumosus em Roraima. O aumento da idade de rebrota resultou em maiores rendimentos de matéria seca (MS), taxa absoluta de crescimento (TAC), taxa de assimilação líquida (TAL), razão de área foliar (RAF) e índice de área foliar (IAF), ocorrendo o inverso quanto à taxa média de crescimento (TMC). A gramínea mostrou-se responsiva à melhoria da fertilidade do solo. A calagem + adubação ou a adubação proporcionaram maiores rendimentos de MS (1.934 e 1.661 kg ha-1), TAC (36,6 e 31,5 kg ha-1 dia-1), TMC (32,5 e 27,9 kg ha-1 dia-1), TAL (4,993 e 4,152 g/m2), RAF (152,9 e 140,9 cm2/g) e IAF (2,42 e 2,14). Para otimizar a eficiência de utilização da forragem produzida e reduzir perdas por senescência da gramínea, o período mais adequado de sua utilização, durante o período chuvoso, situa-se entre 56 e 63 dias com o uso de adubação e calagem + adubação e entre 63 a 70 dias para a testemunha e a calagem.