Rhizosphere-associated microbiota of Canavalia ensiformis in sulfentrazone bioremediation.

The objective of this study was to determine the efficiency of the microbial rhizosphere (Canavalia ensiformis) in the phytoremediation of sulfentrazone using quantification methods (CO2 evolution, microbial biomass carbon, and metabolic quotient) and identification of bacteria (PCR-DGGE technique). The experiment was conducted in a completely randomized design, in a 2x4 factorial scheme, with four replications. The treatments were composed of rhizospheric soil (cultivated with C. ensiformis) and non-rhizosphere soil (uncultivated soil); and four levels of contamination by sulfentrazone (0, 200, 400, and 800 g ha-1 a.i.). The microbiota associated with the rhizosphere of C. ensiformis efficiently reduced sulfentrazone residues in the soil, with better performance at the dose of 200 g ha-1 a.i. Using the PCR-DGGE technique allowed the distinction of two profiles of bacteria in the rhizospheric activity of C. ensiformis. The second bacterial profile formed was more efficient in decontaminating soil contaminated with sulfentrazone residue. The microbiota associated with the rhizosphere of C. ensiformis has an efficient profile in decontaminating soils with residues equivalent to 200 g ha-1 a.i. the herbicide sulfentrazone.

Phytoremediation of soils contaminated with herbicide residues is a viable technique for decontamination of the environment.Canavalia ensiformis has an efficient profile in the decontamination of soils with residue equivalent to 200 g ha⁻¹ a.i. of the herbicide sulfentrazone.The PCR technique and microbial respiration used to analyze the diversity and estimate the bacterial population of a soil are viable tools to evaluate the phytoremediation potential of the microbiota associated with plant species.

Crops with potential for diclosulam remediation and concomitant bioenergy production.

The objective of this work was to evaluate crops for their ability to phytoremediate diclosulam residues in the soil and produce lignocellulosic ethanol. Physiological characteristics, biomass production, soil cover rate, fermentable sugar production and lignocellulosic ethanol production potential of the crops were evaluated in soil with diclosulam residues. The experimental design was a randomized block with four replications. The treatments were arranged in a 4 × 2 factorial scheme with the following crops as the first factor: Avena sativa, Canavalia ensiformis, Mucuna aterrima, and Pennisetum glaucum. The second factor was the presence or absence of the herbicide diclosulam in the soil (30 g ha-1). The physiological variables of the plant species were not affected by the presence of diclosulam; the soil cover of P. glaucum was lower in the area with diclosulam, with a value of 26%. The levels of glucose were not affected by the presence of diclosulam in A. sativa, C. ensiformis, and M. aterrima, indicate not change the estimated yield of ethanol for this species. Avena sativa and Pennisetum glaucum have the potential to phytoremediate soils containing diclosulam residues, with concomitant lignocellulosic ethanol production ability.

Phytoremediation of soils with herbicide residues is a viable tool and has been increasingly widespread throughout the world. The use of plant species capable of making the soil feasible for successive plantings sensitive to previously applied residual herbicides is a way to optimize agricultural production. However, there are few studies in which vegetable biomass used in the phytoremediation process is used. Thus, our study is innovative because it seeks to combine phytoremediation with the production of bioethanol, ensuring even more sustainable agriculture.

Mabea fistulifera and Zeyheria tuberculosa can be indicated for phytoremediation programs of soils contaminated with hormonal herbicides.

Hormone-like herbicides, used for large crops, can contaminate non-target areas with their waste. The objective of this study was to evaluate the tolerance of Mabea fistulifera and Zeyheria tuberculosa to 2,4-D + picloram herbicides by means of morphological and anatomical evaluations. The experiment was performed in a greenhouse in a 4 × 2 factorial scheme. The first factor was the control (without herbicide) and three doses (0.166; 0.333, and 0.666 L ha-1) of the herbicide Tordon® (402 g L-1 2,4-D + 103.6 g L-1 picloram) and the second factor, the species Mabea fistulifera and Zeyheria tuberculosa. The number of M. fistulifera leaves was lower after treatment with the highest dose of the 2,4-D + picloram mixture. The herbicide rates did not influence the number of Z. tuberculosa leaves. The higher dose of 2,4-D + picloram caused a more than 50% reduction in leaf area. Toxicity increased linearly as a function of the doses of the 2,4-D + picloram mixture. Changes in the leaf anatomy of the two species treated with herbicides were observed; however, the roots did not show any changes. Mabea fistulifera and Zeyheria tuberculosa can be recommended for phytoremediation programs in areas contaminated by the herbicides 2,4-D + picloram.

Phytoremediation of soils contaminated with herbicides is a recent and viable tool for environmental decontamination and for the protection of water resources. Mabea fistulifera and Zeyheria tuberculosa can be used to compose riparian forests and retain the arrival of herbicides in the water. Plant anatomy and morphological characteristics are viable tools to assess the tolerance and phytoremediation potential of plant species. Mabea fistulifera and Zeyheria tuberculosa are tolerant to the presence of hormonal herbicides. In this way, they can be used to recover natural areas close to the cultivation areas where the herbicides 2,4-D and picloram are used.

Morphoanatomical injuries in Pistia stratiotes L. (Araceae) as a result of exposure to clomazone in water.

Contamination of water sources due to herbicide is of great concern. Clomazone is a pesticide with a high contamination potential which could possibility lixiviate to water streams. Changes caused by residual herbicide include flora modifications which are generally detrimental for some species. The lack of morphological studies performed in aquatic plants exposed to herbicide-contaminated environments has encouraged the development of our research. For the first time, we present a study that aimed to evaluate leaf injuries visible to the naked eye as well as microscopical effects which may be caused by clomazone on Pistia stratiotes. Pistia stratiotes was subjected to five concentrations of clomazone. Our analysis showed leaf injuries, especially after 15 days of clomazone application. Hormesis was observed when the water lettuce was subjected to the lower concentrations. Total leaf area showed increase following by reduction while injured until reaching the highest concentration. Although the concentrations of clomazone tested in our study are not lethal to water lettuce, such herbicide have still caused morphoanatomical damages on leaves which advocates for the use of P. stratiotes as a bioindicator of the presence of herbicides such as clomazone in water.

The Impact of Metolachlor Applications and Phytoremediation Processes on Soil Microorganisms: Insights from Functional Metagenomics Analysis.

This study assessed the impact of phytoremediation on reducing the residual concentration of metolachlor in soil treated with doses of 530.7 and 1061.4 g/ha and its effect on microbial biodiversity in contaminated areas. For the plant species Avena sativa and Medicago sativa, a significant efficacy of 54.5 and 36.4% was observed in the dissipation of the herbicide, especially at higher doses. Although metolachlor application reduced soil microbial biodiversity, phytoremediating plants, especially M. sativa, promoted greater richness and distribution of microbial species, mitigating the negative effects of the herbicide. Principal component analysis revealed the influence of these plants and metolachlor on the composition of the microbial community. These results highlight the importance of phytoremediation in promoting soil biodiversity and reducing herbicide contamination, providing crucial insights for remediation strategies in contaminated areas.

Potential Distribution of and Sensitivity Analysis for Urochloa panicoides Weed Using Modeling: An Implication of Invasion Risk Analysis for China and Europe.

Urochloapanicoides P. Beauv. is considered one of the most harmful weeds in the United States and Australia. It is invasive in Pakistan, Mexico, and Brazil, but its occurrence is hardly reported in China and European countries. Species distribution models enable the measurement of the impact of climate change on plant growth, allowing for risk analysis, effective management, and invasion prevention. The objective of this study was to develop current and future climate models of suitable locations for U. panicoides and to determine the most influential climatic parameters. Occurrence data and biological information on U. panicoides were collected, and climatic parameters were used to generate the Ecoclimatic Index (EI) and to perform sensitivity analysis. The future projections for 2050, 2080, and 2100 were modeled under the A2 SRES scenario using the Global Climate Model, CSIRO-Mk3.0 (CS). The potential distribution of U. panicoides coincided with the data collected, and the reliability of the final model was demonstrated. The generated model identified regions where the occurrence was favorable, despite few records of the species. Sensitivity analysis showed that the most sensitive parameters of the model were related to temperature, humidity, and cold stress. Future projections predict reductions in climate suitability for U. panicoides in Brazil, Australia, India, and Africa, and an increase in suitability in Mexico, the United States, European countries, and China. The rise in suitability of China and Europe is attributed to predicted climate change, including reduction in cold stress. From the results obtained, preventive management strategies can be formulated against the spread of U. panicoides, avoiding economic and biodiversity losses.

Multivariate analysis reveals significant diuron-related changes in the soil composition of different Brazilian regions.

Sorption and desorption determine the amount of an herbicide in soil solution. Therefore, knowledge of the sorption and desorption coefficients in different soils is an essential factor to estimate the potential for environmental contamination by herbicides. We evaluated the feasibility of multivariate and linear discriminant analyses to predict the sorption and desorption capacity of a soil for diuron, one of the most used herbicides on sugarcane plantations. The adsorptive capacity in twenty-seven Brazilian soil samples was estimated using the sorption constant (Kfs) and desorption constant (Kfd) obtained by the Freundlich isotherms. The regression model was created from the sorbed and nonsorbed concentrations of diuron in soils. Ultra-performance liquid chromatography was applied to quantify the diuron concentrations. The multivariate analysis separated the soils into four groups considering the similarity of the following attributes: pH, organic matter, clay, and base saturation. The groups showed a similar pattern of sorption and desorption for diuron: Lom-Lclay: low sorption (5.9 ± 1.2) and high desorption (10.9 ± 0.6); Lclay: low sorption (7.5 ± 1.1) and high desorption (11.4 ± 1.3); Hom-Hclay: high sorption (11.2 ± 1.2) and low desorption (13.8 ± 1.2); HpH-Hclay: high sorption (10.1 ± 1.1) and medium desorption (11.5 ± 1.4). Linear discriminant analysis of these soil attributes was used to classify other soils described in the literature with adsorption capacity. This analysis was able to identify soils with high and low sorption using the pH, organic matter, clay, and base saturation, demonstrating the enormous potential of the technique to group soils with different contamination risks for subterranean waters. Sugarcane crops in northeastern Brazil showed a higher pollution risk through the leaching of diuron. Multivariate analysis revealed significant diuron-related changes in the soil composition of different Brazilian regions; therefore, this statistical analysis can be used to improve understanding of herbicide behavior in soils.

Tolerance to the herbicide clomazone and potential for changes of forest species / Uso de espécies florestais para diminuição do resíduo de clomazone no ambiente

Clomazone has excelled among Brazilian non-target-site herbicides with high environmental impact. Its high solubility in water can result in leaching, contaminating groundwater and watercourses with possible riparian forest degradation. This situation can be mitigated by phytoremediation process. This study aimed to identify tree species tolerant to clomazone aiming to use them in bioremediation programs. Twelve forest species were evaluated: Inga marginata Willd, Handroanthus serratifolius (A.H. Gentry) S. Grose, Jacaranda puberula Chan, Cedrela fissilis Vell, Calophyllum brasiliense Cambess, Psidium myrsinoides Berg, Tibouchina granulosa Cogn, Caesalpinia ferrea Mart ex. Tul, Caesalpinia pluviosa DC, Terminalia argentea Mart & Zucc, Schinopsis brasiliensis Eng and Schizolobium parahyba (Vell). The statistical analysis was performed in a completely randomized block design with four replications. Three clomazone applications were made each 20 days (60, 80 and 100 days after planting); each application was equivalent to one-half of the recommended rate (2.0 L ha-1). The evaluated parameters were plant height, stem diameter, leaf number, leaf area and dry biomass. The forest species survived the clomazone application; and I. marginata, C. ferrea and S. brasiliensis showed increased tolerance to this herbicide, demonstrating potential for phytoremediation of areas contaminated by clomazone.

Entre os herbicidas com elevado impacto ambiental em sítios não alvo no Brasil, o clomazone tem se destacado. A alta solubilidade desse herbicida em água pode resultar em lixiviação, ocasionando contaminação de mananciais de água subterrânea e cursos d'água, com possível degradação de matas ciliares. Esta circunstância pode ser mitigada por meio de processos de fitorremediação. Este trabalho objetivou identificar espécies arbóreas tolerantes ao clomazone visando utiliza-las em programas de biorremediação. Foram avaliadas doze espécies florestais: Inga marginata Willd, Handroanthus serratifolius (A.H. Gentry) S.Grose, Jacaranda puberula Chan, Cedrela fissilis Vell, Calophyllum brasiliense Cambess, Psidium myrsinoides Berg, Tibouchina granulosa Cogn, Caesalpinia ferrea Mart ex. Tul, Caesalpinia pluviosa DC, Terminalia argentea Mart & Zucc, Schinopsis brasiliensis Eng e Schizolobium parahyba (Vell) Blake. Foi utilizado o delineamento em blocos ao acaso com quatro repetições. Foram feitas 3 aplicações do herbicida clomazone com intervalos de 20 dias (aos 60, 80 e 100 dias após o plantio), cada aplicação foi correspondente a metade da dose comercial de 2.0 L ha-1. Foram avaliados a altura da planta, o diâmetro do caule, o número de folhas, a área foliar e o acúmulo de biomassa seca. Constatou-se que todas as espécies sobreviveram à aplicação de clomazone, contudo I. marginata, C. ferrea e S. brasiliensis apresentaram maior tolerância ao herbicida, demonstrando potencial para o uso em programas de fitorremediação de áreas contaminadas pelo clomazone.

Aspectos biológicos de Tetranychus ludeni Zacher, 1913 (Acari: Tetranychidae) alimentados com folhas de batata-doce pulverizadas com o 2,4-D / Biological aspects of Tetranychus ludeni Zacher, 1913 (Acari: Tetranychidae) fed on sweet potato leaves sprayed with 2,4-D

Batata-doce [Ipomoea batatas (L.) Lam.] apresenta grande versatilidade de usos no Brasil. Com a ampliação das áreas de cultivo, essa espécie estará sujeita à contaminação por herbicidas. Eventualmente, organismos não alvos podem ser expostos aos resíduos. O objetivo deste trabalho foi avaliar aspectos biológicos do ácaro Tetranychus ludeni alimentado com folhas de batata-doce pulverizadas com diferentes doses do herbicida 2,4-D. O experimento foi conduzido no Laboratório de Controle Biológico da Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM), em Diamantina, Minas Gerais. Foram utilizadas 175 fêmeas de T. ludeni e 6 doses de 2,4-D, em g.ha-1 (8,06; 20,15; 40,30; 80,60; 201,50; e 806,00), mais o tratamento-controle com água destilada. Adotou-se delineamento inteiramente casualizado, com sete tratamentos e cinco repetições, contendo cinco fêmeas de T. ludeni em cada repetição. Foram avaliados a mortalidade inicial do ácaro em 24 h, o número de ovos, as ninfas e a longevidade das fêmeas. Os dados foram submetidos à análise de variância, sendo as médias significativas analisadas pelo teste de Duncan. Observou-se que doses maiores desse herbicida podem aumentar a mortalidade e reduzir a longevidade das fêmeas de T. ludeni.(AU)

Sweet potato [Ipomoea batatas (L.) Lam.] presents great versatility of uses in Brazil. With the expansion of crop areas, this species is subject to contamination by herbicides. Eventually, non-target organisms can be exposed to residues . The aim of this study was to evaluate biological aspects of the mite Tetranychus ludeni fed on sweet potato leaves sprayed with different doses of the herbicide 2,4-D. The experiment was conducted at the Biological Control Laboratory of Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM), Diamantina, Minas Gerais, Brazil. Altogether, 175 females of T. ludeni and six doses of 2,4-D, in g.ha-1 (8.06, 20.15, 40.30, 80.60, 201.50, and 806,00) were used, plus the control done with distilled water. It was adopted a completely randomized design with seven treatments and five replications with five females each. Early mortality of T. ludeni (24 h), the number of eggs, nymphs and longevity of females were evaluated. Data were subjected to analysis of variance, being the significant mean analyzed by Duncan test. It was observed that high doses of the herbicide may increase the mortality and decrease longevity of females of T. ludeni.(AU)

Influência do tamanho do vaso e época de avaliação sobre o crescimento do picão preto em competição com milho e soja / Influence of the cup size and time of evaluation on growth black jack in competition with corn and soybean

A avaliação dos efeitos da competição das plantas daninhas sobre o crescimento de culturas como milho e soja é efetuada por meio de ensaios em ambientes protegidos para maior precisão experimental e segurança nos resultados obtidos. Esses ensaios geralmente são feitos em recipientes (vasos) onde se testam os efeitos desejados em épocas após plantio. O tamanho do vaso quando pequeno pode limitar o desenvolvimento da planta pelo volume de substrato neles contido. No entanto, essa limitação está diretamente relacionada às espécies em desenvolvimento e ao tempo de avaliação. Assim objetivou-se com este trabalho verificar o efeito do volume de vasos na capacidade competitiva das plantas de picão-preto, milho e soja em diferentes épocas de avaliação. O milho apresentou-se mais competitivo com o picão-preto que a soja tanto nos diferentes tamanhos de vaso quanto nas diferentes épocas. Dentro do intervalo testado, recomenda-se o uso de vasos com volume de 16 dm3, devido à baixa tendência de estabilização das curvas do modelo proposto. Por este motivo também, pode-se afirmar que intervalos iguais ou inferiores a 60 dias são inadequados para os ensaios de competição das plantas de picão-preto com milho ou soja.

The evaluation of the effects of weed competition on growth from crops like corn and soybeans is done by testing in protected environments for increased accuracy and confidence in experimental results. These tests are usually done in containers (pots) where they test their desired times after planting. The small size of the vessel when could limit development of the plant the volume of the substrate contained therein. However, this limitation is directly related to the species in the development and evaluation time. Thus the objective of this work is to verify the effect of the volume of vessels in the competitive ability of plants black jack, corn and soybean at different sampling times. The corn had become more competitive with black jack soybean so that the vessel in different sizes and at different times. Within the range tested, it is recommended the use of vessels with a volume of 16 dm 3, due to the low tendency to stabilize model curves. For this reason, too, can say what intervals not exceeding 60 days are inadequate for field trials of plants black jack with corn or soybeans.

Atividade microbiana do solo, controle de plantas daninhas e crescimento da mandioca após a aplicação de herbicidas / Soil microbial activity, weed control and growth of cassava after application of herbicide

São poucas as informações na literatura sobre herbicidas para aplicação em pós-emergência da cultura da mandioca e seus possíveis impactos na atividade microbiana do solo. Dessa forma, objetivou-se com este trabalho avaliar o efeito da aplicação de herbicidas pós-emergentes em área total e dirigida na atividade microbiana de solo cultivado com mandioca, bem como seu efeito no controle das plantas daninhas e no crescimento inicial da cultura. O experimento foi conduzido em campo, no Distrito do Planalto, na cidade de Diamantina-MG. O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições e os tratamentos foram constituídos de uma testemunha capinada, uma testemunha cultivada sem o controle de plantas daninhas e a aplicação dos herbicidas: fluazifop-p-butil, fomesafen, glyphosate, paraquat e a mistura de herbicidas fluazifop-p-butil + fomesafem. De maneira geral, os herbicidas estudados apresentaram controle satisfatório das plantas daninhas presentes na área de plantio e causaram baixa intoxicação visual à mandioca. A mistura dos herbicidas fomesafen e fluazifop-p-butil promoveram um controle mais prolongado das plantas infestantes, mas com influência negativa à microbiota do solo. Os herbicidas paraquat e glyphosate apresentaram potencial para aplicação dirigida nas entrelinhas da mandioca.

There is little information in the literature on herbicides for post-emergence application of cassava and its potential impacts on soil microbial activity. Thus, the aim of this work was to evaluate the effect of postemergence herbicides in total area and direct microbial activity in soil cultivated with cassava, as well as its effect on weed control and early growth of the crop. The experiment was conducted in the field, in the Planalto District, the city of Diamantina-MG. The experimental design was a randomized block with four replications and treatments were made up of one weed control, one control grown without weed control and herbicide application: fluazifop-p-butyl and fomesafen, glyphosate, paraquat and the mixture herbicide fluazifop-p-butyl + fomesafem. In general, the herbicides showed satisfactory control of weeds in the planting area and caused low toxicity to visual cassava. The mixture of herbicides fomesafen and fluazifop-p-butyl promoted a more prolonged control of weeds, but with negative influence on soil microbes. The herbicide paraquat and glyphosate showed potential for application directed between the lines of cassava.

Características fisiológicas do cafeeiro em competição com plantas daninhas / Physiological characteristics of coffee plants in competition with weeds

Quando plantas estão submetidas à alta competição, as características fisiológicas normalmente são alteradas, o que resulta em diferenças no aproveitamento dos recursos do ambiente, principalmente no uso da água, que influencia de modo direto a disponibilidade de CO2 no mesofilo foliar e a temperatura da folha e, conseqüentemente, a eficiência fotossintética da planta. Diante do exposto, objetivou-se com este trabalho avaliar as características associadas à atividade fotossintética de folhas jovens e maduras em plantas de cafeeiro cultivadas em competição com Mucuna aterrima, Brachiaria plantaginea e Brachiaria decumbens, bem como, o efeito da densidade dessas espécies daninhas na cultura. As folhas mais maduras do cafeeiro se diferenciaram das folhas mais jovens por apresentar maiores valores de taxa fotossintética (A), taxa de transpiração (E), condutância estomática (Gs), consumo de CO2 (C) e a eficiência no uso da água (EUA) (exceto quando a cultura é cultivada na presença de B. decumbens). O aumento da densidade de M. aterrima promoveu o incremento do C e da E das plantas de café, assim como, o cultivo com B. decumbens aumentou a Concentração de CO2 subestomática (Ci) da cultura; já para B. plantaginea não houve influência da densidade nos parâmetros fisiológicos estudados. Pode-se concluir que as plantas de M. aterrima são mais competitivas quando presentes em menores densidades, influenciando negativamente o C, a Gs, a E e a A do cafeeiro, já B. decumbens possui maior habilidade competitiva quando em maior densidade, reduzindo a E, Gs e a A do cafeeiro.

When plants are exposed to high competition, the physiological characteristics of growth and development are usually altered, resulting in differences in the use of environmental resources, especially water use, so that influences directly the availability of CO2 in mesophyll and foliar leaf temperature and, consequently, the photosynthetic efficiency of the plant. Given the above, the aim of this study was to evaluate the characteristics associated with photosynthetic activity of young and mature leaves in coffee plants grown in competition with Mucuna aterrima, Brachiaria decumbens and Brachiaria plantaginea as well as the effect of the density of these weeds that culture. The leaves mature coffee differ from younger leaves due to the higher values of photosynthetic rate (A), transpiration rate (E), stomatal conductance (Gs), CO2 consumption (C) and water use efficiency (USA) (except where the crop is grown in the presence of B. decumbens). The increased density of M. aterrima, promoted the increase of C and E of the coffee plants, as well as B. decumbens increased substomatal CO2 concentration (Ci) of culture, as for B. plantaginea no influence of density on physiological parameters studied. It can be concluded that the plants M. aterrima are more competitive when present in lower densities, negatively influencing C, Gs, E and A coffee since B. decumbens has greater competitive ability while at higher density, reducing the E, A and Gs coffee.