Phytoremediation of Cu-contaminated vineyard soils in Brazil: A compendium of Brazilian pot studies.

Vineyard soils can be contaminated by copper (Cu) due to successive applications of fungicides and organic fertilizers. Soil remediation can be addressed by altering soil properties or selecting efficient Cu-extracting cover crops tolerant to Cu toxicity. Our objectives were to synthesize the Cu-extracting efficiency by plant species tested in Brazil, classify them according to Cu resistance to toxicity, and assess the effect of soil properties on attenuating Cu toxicity. We retrieved results from 41 species and cultivars, totaling 565 observations. Freshly added Cu varied between 50 and 600 mg Cu kg-1 of soil across studies. The partition of Cu removal between the above- and below-ground portions was scaled as a logistic variable to facilitate data synthesis. The data were analyzed using the Adaboost machine learning model. Model accuracy (predicted vs. actual values) reached R2  = 0.862 after relating species, cultivar, Cu addition, clay, SOM, pH, soil test P, and Cu as features to predict the logistic target variable. Tissue Cu concentration varied between 7 and 105 mg Cu kg-1 in the shoot and between 73 and 1340 mg Cu kg-1 in the roots. Among soil properties, organic matter and soil test Cu most influenced the accuracy of the model. Phaseolus vulgaris, Brassica juncea, Ricinus communis, Hordeum vulgare, Sorghum vulgare, Cajanus cajan, Solanum lycopersicum, and Crotolaria spectabilis were the most efficient Cu-extracting cover crops, as shown by positive values of the logistic variable (shoot removal > root removal). Those Cu-tolerant plants showed differential capacity to extract Cu in the long run.

Physiological and biochemical characterization of copper-toxicity tolerance mechanism in grass species native to Pampa Biome and Atlantic Forest for use in phytoremediation.

Orchards and vineyards account for significant copper (Cu) accumulation in the soil due to frequent Cu fungicide applications to control leaf diseases. Although grass species are distributed in these areas likely because of their physiological mechanisms to combat Cu toxicity-related stress, the aim of the present study is to identify grass species presenting biochemical-physiological responses that feature adaptive Cu toxicity tolerance mechanisms. Three grass species native to the Pampa and Atlantic Forest biomes (Paspalum notatum, P. plicatulum, and P. urvillei) and an exotic species (Cynodon dactylon) were tested. Plants were cultivated in pots filled with 4 kg of typic Hapludalf soil, under two Cu availability, control, and toxicity conditions (80 mg Cu kg soil-1). Photosynthetic parameters, relative growth rate, root dry matter, shoot dry matter, the activity of stress-fighting enzymes (superoxide dismutase and guaiacol peroxidase), root biometry, soluble organic carbon, soil pH, and electrical conductivity were evaluated. P. notatum and P. urvillei have physiological characteristics that allow high translocation factor and Cu accumulation in the root and shoot, and it allows their use in phytoremediation processes due to (1) greater activity of stress-fighting enzymes such as POD in the shoot; (2) to larger diameter roots, which allow greater Cu complexation in them - they are lesser sensitive to stress caused by Cu than the other species; and (3) greater soluble organic carbon exudation in the rhizosphere than species P. plicatulum and C. dactylon, which can complex Cu2+ and reduce the presence of forms toxic to plants.

The tolerance of grapevine rootstocks to copper excess and to the use of calcium and phosphorus to mitigate its phytotoxicity.

High soil copper (Cu) concentrations in vineyards can cause phytotoxicity to grapevine rootstocks. In order to mitigate toxicity, the use of grapevine rootstock genetic variation and the application of amendments are possible strategies. The aim of this study is to assess the tolerance of grapevine rootstocks to Cu excess and whether phosphorus (P) and calcium (Ca) can reduce phytotoxicity caused by Cu. Grapevine rootstock seedlings were produced from selected stakes: Paulsen 1103 (Vitis berlandieri × Vitis rupestris); SO4 (Vitis berlandieri × Vitis riparia); IAC 572 ((Vitis Riparia × Vitis rupestris) × Vitis caribaea); and Isabel (Vitis labrusca). Seedlings were grown in nutrition solution added with the following treatments: 0.3 µM Cu (control); 60 µM Cu; 60 µM Cu and 62 mg L-1 P; 60 µM Cu and 400 mg L-1 Ca. High Cu concentration caused phytotoxicity in all rootstocks, impairing their growth and decreasing nutrient concentration and photosynthetic activity. P and Ca addition had positive effect on the photosynthetic activity of all rootstocks, although it was not enough to revert growth to levels comparable with controls. Overall, based on the results, the application of P and Ca was not efficient in mitigating Cu phytotoxicity in grapevine plants grown in solution. Isabel was the most sensitive rootstock to Cu phytotoxicity, whereas Paulsen 1103 and SO4 presented more tolerance and can be used, together with other management strategies, in contaminated vineyard areas. Therefore, careful genotype rootstock selection for use in high Cu soils is important, while Ca and P are not efficient mitigators of Cu toxicity.

Natural abundance analysis of the role played by 15 N as indicator for the certification of organic-system deriving food.

BACKGROUND: The natural abundance of stable isotope 15 N (δ15 N) in production systems has emerged as an alternative to distinguish organic products from conventional ones. This study evaluated the use of δ15 N values recorded for nitrogen fertilizers, soil and plant tissue in order to set the differences between organic and conventional agricultural production systems applied to rice, potatoes, apple and banana crops. RESULTS: Values of δ15 N recorded for N sources ranged from +5.58‰ to +18.27‰ and from -3.55‰ to +3.19‰ in organic and synthetic fertilizers, respectively. Values recorded for δ15 N in food from organic rice, potatoes and banana farms were higher than values recorded for δ15 N in conventional farms; the same was observed for values recorded for δ15 N in leaves from the four crops. CONCLUSION: Results have allowed for differentiation between production systems due to values of δ15 N recorded in leaves of all crops and food, for rice, potatoes and banana trees. © 2021 Society of Chemical Industry.

Tolerance and phytoremediation potential of grass species native to South American grasslands to copper-contaminated soils.

Grass species native to South American can have mechanisms to tolerate copper (Cu) excess, which improves their use to phytoremediate Cu-contaminated soils . The aims of the present study are to assess the tolerance of grass species native to South American grasslands to copper-contaminated soils, as well as their adaptive responses under high Cu-stressed condition and to identify native grass species presenting the highest potential to be used for phytoremediation purposes. Soil samples were air-dried and their acidity, phosphorus and potassium levels were corrected, and the samples were incubated. Three Cu levels were used in the experiment: natural (Dose 0), with added of 40 mg kg-1 of Cu and with added of 80 mg kg-1 of Cu. Three Axonopus affinis, Paspalum notatum and Paspalum plicatulum seedlings were transferred to 5-L pots filled with soil in August and grown for 121 days. Soil solution was collected during cultivation with the aid of Rhizon lysimeters. Main concentrations of cations and anions, dissolved organic carbon and pH in the soil solution were analyzed and the ionic speciation was carried out. Cu toxicity impaired the growth of grass species native to South America, since Cu excess led to both changes in root morphology and nutritional unbalance. Among all assessed native species, Paspalum plicatulum was the one presenting the greatest potential to phytostabilize in Cu-contaminated soils, since it mainly accumulates Cu absorbed in the roots; therefore, its intercropping with grapevines is can be beneficial in Cu-contaminated soils.

Spatial variation of herbaceous cover species community in Cu-contaminated vineyards in Pampa biome.

Study's objective was to evaluate spatial variability of herbaceous cover species community in vineyards cultivated in soil with increasing Cu levels in Pampa biome. Three vineyards, with increasing soil Cu available contents and a natural field area (NF), were selected. In each experimental area, soil Cu content, botanical composition, cumulative aerial biomass, and aerial part Cu concentration, in most frequent species, were evaluated. In total, 39 vascular plant species were identified, including four exotic species. Biodiversity indicators did not significantly correlate with soil Cu. However, botanical composition variation could be observed. In NF, Poaceae and Asteraceae families presented greater dry mass contribution, while this contribution decreased in higher soil Cu concentration areas. The Cu concentration and accumulation in plant aerial part were higher in older vineyards, as plant aerial part accumulated, in average, 13.8 mg Cu m-2. Among species found in experimental fields, Ageratum conyzoides, a species known to form Cu-tolerant populations, occurred in most areas, especially in vineyards, presenting higher aerial Cu concentrations, with a mean of 126.47 mg kg-1. Soil enrichment with Cu did not alter the vegetation's biodiversity, but may have contributed to the botanical composition modification. The native species, P. plicatulum and A. conyzoides, presented a high bio-accumulation factor and are potential candidates for phytoremediation techniques.

Iron fertilization to enhance tolerance mechanisms to copper toxicity of ryegrass plants used as cover crop in vineyards.

Ryegrass (Lolium perenne L.) is a plant species that can express mechanisms of tolerance to copper (Cu) toxicity. Therefore, the agronomical approach of intercropping system with ryegrass may represent a promising tool to limit the onset of Cu toxicity symptoms in the other intercropped plants species, particularly when an inadequate nutrient availability like iron (Fe) shortage is also concurrently present. This study aimed at assessing the mechanisms involved in the mitigation of Cu phytotoxicity and the stress effects on plant growth, root morphology and nutrition of ryegrass fertilized with two different Fe sources. To this purpose, seedlings of ryegrass were hydroponically grown for 14 days in controlled conditions with 4 different levels of Cu (0.2, 5.0, 25 and 50 µM) and with either 100 µM Fe-EDDHA or Fe-EDTA. Results show that high levels of Cu availability enhanced the root content of organic anions as well as the root exudation. Different Fe fertilizations at the condition of 50 µM Cu induced changes in root phenolic compounds, citrate and fumarate contents and the exudation pattern of phenolic compounds. Differences in plant growth were not observed between the two Fe sources, although Cu concentration in plant tissue fed with Fe-EDTA was lower in the condition of 50 µM Cu. The enhanced root exudation of Cu-complexing organic compounds (including phenolics) in ryegrass plants when exposed to excessive Cu availability could be at the basis of the ameliorated edaphic rhizosphere conditions (lower Cu availability). For this reason, from the agronomical point of view ryegrass plants used in intercropping systems with crops like vine plants could represent a promising strategy to control Cu toxicity in vineyard soils. Further studies under the field conditions must be taken to support present findings.

Intercropping of young grapevines with native grasses for phytoremediation of Cu-contaminated soils.

Intercropping may be a strategy for phytoremediation of vineyard soils with high copper (Cu) content. The study aimed to evaluate the contribution of South American native grasses in limiting Cu availability and toxicity in soils grown with grapevines. The soil used in the experiment was collected in natural grassland with no history of cultivation. The samples were air-dried; acidity, P and K levels were corrected and samples were then incubated. We used three Cu levels - natural content (Dose 0) and the addition of 40 and 80 mg Cu kg-1 of soil (Dose 40 and 80). At each Cu dose, grapevine was grown in three cropping treatments: monocropping, intercropping with Paspalum plicatulum and intercropping with Axonopus affinis. In intercropping, two grass seedlings were transplanted into each experimental unit 35 days prior to the transplanting of the grapevines. The soil solution was sampled and ionic speciation was carried out. At 70 days after planting, we sampled the grapevines to determine dry matter, morphological parameters and nutrient concentration in the roots and shoots. Intercropping young grapevines with Paspalum plicatulum and Axonopus affinis was efficient in promoting the growth of young grapevines at moderate and low levels of Cu contamination by reducing Cu bioavailability. This indicates that maintaining native grasses in young vineyards is an effective strategy for phytoremediating Cu-contaminated soils and obtaining a grape production system with reduced interventions in the native environment, in addition to contributing to soil protection and nutrient cycling.

Growth and chemical changes in the rhizosphere of black oat (Avena strigosa) grown in soils contaminated with copper.

Copper based pesticides are used to protect vineyards from fungal infections. Plants like black oats (Avena strigosa Schreb) can promote chemical changes in the rhizosphere, reducing copper (Cu) bioavailability in contaminated soils. The objective of this study was to evaluate how copper additions would affect growth, morphology and nutrient uptake by black oats and how the plants affect the chemical composition in rhizosphere and bulk soil. The soil was collected in grassland of southern Brazil. The soil was air-dried, adjusted pH and added phosphorus and potassium amendments, and then it was incubated. Three Cu levels were established in the soil with the addition of 0, 40 and 80 mg Cu kg-1. The experimental design consisted of pots containing 8 plants with 10 kg of soil. Rhizosphere (2 kg of soil) and bulk (8 kg of soil) separated by a 30 µm nylon membrane. Black oat plants were grown for 54 days. The soil and solution were chemically characterized throughout cultivation for Cu speciation. At 54 days after emergence, the soil was sampled and proceeded chemical analysis and plants were collected to determine yield dry matter, morphological parameters and nutrient concentration. Black oat plants induce increase of pH and dissolved organic carbon in the rhizosphere. These root-induced processes increase the percentage of complexed chemical species and decrease free Cu+2 in soil solution, decreasing Cu toxicity. However, soil contamination with Cu induces morphological changes and nutritional imbalances. Black oats could thus be planted along with vineyards, for such increasing protect the soil and promote nutrient cycling, as well as reduce the free Cu available fraction due to the root-induced modifications in the rhizosphere.

Growth, biochemical response and nutritional status of Angico-Vermelho (Parapiptadenia rigida (Bentham) Brenan) under the application of soil amendment in Cu-contaminated soil.

Forest species Angico-Vermelho (Parapiptadenia rigida (Bentham) Brenan) is an alternative for the revegetation of areas contaminated with high levels of heavy metals such as copper (Cu). However, excess Cu may cause toxicity to plants, which is why the use of soil amendments can facilitate cultivation by reducing the availability of Cu in the soil. The aim of this study was to assess how the use of amendment can contribute to growth and nutritional status as well as reduce oxidative stress in Angico-Vermelho grown in Cu-contaminated soil. Samples of a Typic Hapludalf soil containing high Cu content were used for the application of four amendments (limestone, organic compost, Ca silicate and zeolite), in addition to a control treatment. The treatments were arranged in a completely randomized design, with four replicates. The use of amendments decreased Cu content available in soil and contributed to improve both plant nutritional status and its antioxidant response expressed by enzymatic activity. The application of the amendments, especially zeolite and Ca silicate, increased dry matter yield of Angico-Vermelho. Thus, the results presented here suggest that the use of amendments contributes to improving Cu-contaminated soils and favors revegetation with Angico-Vermelho.

Physiological and nutritional status of black oat (Avena strigosa Schreb.) grown in soil with interaction of high doses of copper and zinc.

Vineyard sandy acid soils from South Brazil have experienced heavy metal contamination due to replacement of copper (Cu)-based by zinc (Zn)-based products to control foliar diseases. Thus, we evaluate physiological and nutritional status of black oat (Avena strigosa Schreb.), a common interrow crop in vineyards from this region. Soil was collected in a natural field from Santana do Livramento, in Rio Grande do Sul, the southernmost state of Brazil. Black oat was cultivated for 30 days in a greenhouse with application of 0, 30, and 60 mg Cu kg(-1) combined with 0, 15, 30, 60, 120, and 180 mg Zn kg(-1). After the trial period, dry matter accumulation of roots and shoots, Cu and Zn contents in roots and shoots, chlorophyll a fluorescence, photosynthetic pigments and catalase (CAT, EC 1.11.1.6) and peroxidase (POD, EC 1.11.1.7) activity were determined. Cu and Zn toxicity was evidenced by the decrease in plant growth of black oat as well as by the decrease of photochemical efficiency associated with the decrease in photosynthetic pigment content, especially with the highest doses of Cu and Zn. Furthermore, the activity of antioxidant enzymes (CAT and POD) was increased in intermediate doses of Zn, indicating the activation of the antioxidant system, but the stress condition in treatments with high levels of Cu and Zn was not reversed.

Biochemical changes in black oat (avena strigosa schreb) cultivated in vineyard soils contaminated with copper.

Soils used for the cultivation of grapes generally have a long history of copper (Cu) based fungicide applications. As a result, these soils can accumulate Cu at levels that are capable of causing toxicity in plants that co-inhabit the vineyards. The aim of the present study was to evaluate growth parameters and oxidative stress in black oat plants grown in vineyard soils contaminated with high levels of Cu. Soil samples were collected from the Serra Gaúcha and Campanha Gaúcha regions, which are the main wine producing regions in the state of Rio Grande do Sul, in southern Brazil. Experiments were conducted in a greenhouse in 2009, with soils containing Cu concentrations from 2.2 to 328.7 mg kg(-1). Evaluated parameters included plant root and shoot dry matter, Cu concentration in the plant's tissues, and enzymatic and non-enzymatic biochemical parameters related to oxidative stress in the shoots of plants harvested 15 and 40 days after emergence. The Cu absorbed by plants predominantly accumulated in the roots, with little to no translocation to the shoots. Even so, oat plants showed symptoms of toxicity when grown in soils containing high Cu concentrations. The enzymatic and non-enzymatic antioxidant systems of oat plants were unable to reverse the imposed oxidative stress conditions.

Copper availability assessment of Cu-contaminated vineyard soils using black oat cultivation and chemical extractants.

Grapevines grown on acid soils with low fertility in southern Brazil are treated with intense foliar applications of copper (Cu) fungicides, resulting in an increased level of Cu in the soil and increased toxicity. The present study evaluated the accumulation and bioavailability of Cu, and soils with varying levels of Cu from the main producing regions of southern Brazil were collected. The forms of Cu present in the soil were assessed using chemical extractants; additionally, oat cultivation was performed, reflecting the use of the plant as an indicator of Cu bioavailability. Cu accumulated in the topsoil, mainly in bioavailable forms, and there was also an increase of Cu up to a depth of 0.4 m. Cu was primarily found in the mineral fraction, with apparent saturation of the soil organic matter functional groups. Inceptisol and Alfisol soils with a long history of cupric fungicide application were found to have levels of Cu toxic to oat plants. Furthermore, accumulated copper in Alfisol soil from the Campanha Gaúcha region of the state of Rio Grande do Sul had higher bioavailability compared to Cu accumulated in Inceptisol soil from the Serra Gaúcha region. In addition, the copper concentration in roots was found to serve as an indicator of Cu bioavailability in soil, but not of copper phytotoxicity in plants.

Triggered antioxidant defense mechanism in maize grown in soil with accumulation of Cu and Zn due to intensive application of pig slurry.

The present study investigated changes in both the growth parameters and the enzymatic and non-enzymatic antioxidant systems of maize (Zea may L.) plants grown in Typic Hapludalf soil containing an accumulation of Cu and Zn. This accumulation developed because the soil received nineteen applications of pig slurry in no-tillage system over seven years. In this study, the maize plants were grown for fifteen and 25 days after emergence (DAE) in pots containing undisturbed and disturbed soil samples collected from a field experiment that received the rates 0, 20, 40 and 80m(3)ha(-1) of pig slurry, which totalized the amount of 0, 380, 760 and 1520m(3)ha(-1) of pig slurry in seven years, respectively, and phosphorus (P)+potassium (K) treatment (in disturbed soil samples). The maize plants grown in the undisturbed soil samples with an accumulation of Cu and Zn did not indicate an apparent decrease in growth. However, when compared to the treatment with PK fertilization, the maize plants grown in the disturbed soil with pig slurry treatments indicated higher lipid peroxidation and a number of senescent leaves, as well as a significant decrease in plant height. Additionally, when compared to the PK treatment, the leaf superoxide dismutase and ascorbate peroxidase activities decreased and increased, respectively, with the addition of pig slurry treatments in the disturbed soil at 25 DAE. In general, when compared to the treatments with 20m(3)ha(-1) of pig slurry and PK at fifteen and 25 DAE, the leaf ascorbic acid and non-protein thiol groups concentrations decreased with the addition of 40 and 80m(3)ha(-1) of pig slurry. This result suggests that the excess of Cu and Zn in the pig slurry significantly changed the antioxidant system of the maize plants.

Lixiviação e volatilização de nitrogênio em um Argissolo cultivado com videira submetida à adubação nitrogenada / Lixiviation and volatilization of nitrogen in Sandy Typic Hapludalf soil cultivated with grapevine submitted to the nitrogen fertilization

O nitrogênio (N) aplicado na superfície do solo em vinhedos pode ser perdido por volatilização ou lixiviação, sendo uma das possíveis explicações para o baixo aproveitamento de N pelas videiras. O trabalho objetivou avaliar as perdas de N por volatilização e lixiviação do N mineral em solo cultivado com videira submetida à adubação nitrogenada. Foram instalados dois experimentos em um vinhedo de Cabernet Sauvignon, em Rosário do Sul (RS), Brasil. No experimento 1, foram instalados lisímetros no solo que recebeu a aplicação de 0, 40, 80 e 120kg de N ha-1 ano-1 na forma de ureia e, durante o período de agosto a dezembro de 2009, foi coletada a solução do solo para a análise de N mineral. No experimento 2, foram instaladas câmaras coletoras no solo que recebeu, em agosto de 2010, a aplicação de 0, 20, 40, e 80kg de N ha-1 ano-1 na forma de ureia, 40kg de N ha-1 ano-1 de composto orgânico e 40kg de N ha-1 ano-1 de ureia revestida com polímeros, para avaliar a volatilização de N-NH3 do momento da aplicação até 80 horas depois da aplicação. As maiores concentrações de nitrogênio mineral na solução lixiviada foram encontradas nas doses mais elevadas de fertilizante mineral aplicado e ao longo da brotação e florescimento das videiras, o que pode diminuir o aproveitamento do nutriente pelas plantas. Os maiores fluxos e perdas de amônia do solo cultivado com videira para a atmosfera aconteceram nas doses mais elevadas de nitrogênio mineral aplicado, especialmente, depois de 44 horas da sua aplicação sobre a superfície do solo. A aplicação de ureia revestida com polímeros e composto orgânico promoveram as menores perdas de amônia por volatilização, o que pode estimular o aproveitamento de nitrogênio pelas videiras.

Nitrogen (N) applied in vineyards may be lost through volatilization or lixiviation. Two experiments were carried out to evaluate the N losses through volatilization or lixiviation in vineyard submitted the N fertilization, at Sandy Typic Hapludalf soil in Southern Brazil. In the experiment 1, the treatments were applications of 0, 40, 80 and 120kg N ha-1, as urea form, and analyze N concentration in soil solution. The soil solution was collected by lysimeters during the cycle of the grapevines. In the experiment 2, the treatments were 0, 20, 40, and 80kg N ha-1, as urea form, 40kg ha-1 N as composed organic form and 40kg N ha-1 as urea covered with polymer to evaluate ammonia volatilization until 80 hours after N fertilization. The largest concentration of mineral nitrogen were detected in the leach solution from treatments of higher doses of mineral fertilizer, along the budding and along the flowering of grapevines and this factors may decrease the nutrient efficiency. The largest flows and losses of ammonia to the atmosphere from a soil cultivated with grapevines happened at treatments with highest doses of mineral nitrogen. The highest lose happened 44 hours after fertilizer application on soil surface. The application of urea coated with polymers and organic compounds showed the smallest ammonia losses by volatilization, which may improve nitrogen efficiency by grapevines.