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Drought stress is a common environmental factor that constrains plants from expressing their ecophysiological potential, disrupting various physiological and biochemical processes. Hence, the objective of this work was to evaluate the growth, development and photosynthetic performance under drought in the vegetative phenological stage of soybean in two lineages with potential difference tolerance to this abiotic stress, lineages (‘Vx-08-10819’ and ‘Vx-08-11614’. For this purpose, biometric traits of development, relative water content in leaves, photosynthetic pigments, gas exchange, and chlorophyll a fluorescence were evaluated. The experimental design was a randomized block design with 4 replications and arranged in a 2 × 3 factorial scheme, comprising of two soybean lineages (Vx-08-10819 and Vx-08-11614) in combination with three water availability [100% (control), 60%, and 40% of field capacity]. Relative water content in leaves, total leaf area, and shoot dry weight of lineage Vx-08-10819 were not changed after exposure to drought. Besides that, photosynthetic capacity of lineage Vx-08-10819 was less affected than lineage Vx-08-11614 to drought, showing that this lineage is tolerant to this abiotic stress in at vegetative stage V4. Keywords: chlorophylls; gas exchange; Glycine max (L.) Merr; water relations. Crescimento, desenvolvimento e desempenho fotossintético de duas linhagens de soja em resposta à seca RESUMO: O estresse hídrico é um fator ambiental comum que impede as plantas de expressarem seu potencial ecofisiológico, interrompendo vários processos fisiológicos e bioquímicos. Portanto, o objetivo deste trabalho foi avaliar o crescimento, o desenvolvimento e o desempenho fotossintético sob seca na fase fenológica vegetativa da soja em duas linhagens com potencial diferença na tolerância a este estresse abiótico, as linhagens Vx-08-10819 e Vx-08-11614. Para tanto, foram avaliadas características biométricas de desenvolvimento, teor relativo de água nas folhas, pigmentos fotossintéticos, trocas gasosas e fluorescência da clorofila a. O delineamento experimental foi em blocos casualizados com 4 repetições e dispostos em esquema fatorial 2 × 3, composto por duas linhagens de soja (Vx-08-10819 e Vx-08-11614) em combinação com três disponibilidades hídricas [100% (controle), 60% e 40% da capacidade de campo]. O conteúdo relativo de água nas folhas, a área foliar total e o peso seco da parte aérea da linhagem Vx-08-10819 não foram alterados após a exposição à seca. Além disso, a capacidade fotossintética da linhagem Vx-08-10819 foi menos afetada do que a linhagem Vx-08-11614 à seca, mostrando que esta linhagem é tolerante à este estresse abiótico no estágio vegetativo V4. Palavras-chave: clorofilas; troca gasosa; Glycine max (L.) Merr; relações hídricas.

In the present study, we investigated the sites of aluminum (Al) accumulation and its effects on the growth, morphology and nutritional status in root tips of soybean (Glycine max L.) genotype Conquista. The seedlings were exposed to nutrient Clark solution, pH 4.0, with 0 (control) and 100 µM of Al for 24, 48 and 72 h. Our results showed an Al accumulation in the superficial layers of the root tip, such as the root cap cells, epidermis and cortex cells, and internally in the cell walls of the meristematic cells. The Al accumulation in the outer cells prevented the entry of this metal in the inner tissues. However, scanning electron micrographs showed damage in the external micromorphology of the root tips. This damage resulted in cellular disorganization in the root cap and epidermis cells leading to a reduction in Ca and Mg uptake. Despite that, there was no change in root growth. Taken together, our findings suggest that genotype Conquista has a capacity to avoid Al toxicity, probably by Al immobilization in the cell walls and in the external tissues of the root tip.

Phosphorus (P) is one of the nutrients most required by plants, especially in the initial phase, however, there are species whose growth effects promoted by phosphorus are still unknown. Therefore, this study aimed to test whether increasing levels of phosphorus influence the physiological and morphological behavior and the quality of seedlings of Guazuma ulmifolia. For that purpose, the seedlings were grown in a substrate produced only with Dystrophic RED LATOSOL (Oxisol) under a completely randomized design and subjected to five levels of phosphorus (0, 100, 200, 300, and 400 mg dm-3 ). At 120 days, the biometric and physiological evaluations were performed, and the chlorophyll indices, biomass, allometric relationships, Dickson Quality Index, and the phosphorus content were determined. The data were subjected to analysis of variance by the F-test and subsequently to regression analysis and Pearson’s linear correlation. Phosphorus fertilization promoted significant gains (p ? 0.05) for all variables morphological e physiological, except for the specific leaf area and allometric relationships. The phosphorus content was positively correlated with all tested variables. Based on the results obtained, it is concluded that the seedlings responded positively to phosphorus fertilization. Furthermore, phosphorus fertilization promoted better physiological and morphological performance and higher seedling quality.

Fluoride (F) is one of the main environmental pollutants, and high concentrations are commonly detected in the air and in both surface and groundwater. However, the effects of this pollutant on seed germination and on the initial growth of crop seedlings are still poorly understood. In this context, the aim of this study was to assess morphoanatomical, physiological and biochemical fluoride effect indicators inThe germination parameters, and anatomical, morphological, physiological, biochemical and nutritional characteristics of the seedlings did not show negative effects from exposure to KF at the lowest doses evaluated. On the other hand, treatment with the highest dose of KF (30 mg LOur findings demonstrated that

Glutathione is essential for plant tolerance to arsenic but few studies have focused on the coordination between the enzymes involved in its metabolism. We exposed Pistia stratiotes to four treatme...

Phytoremediation is considered an ecologically beneficial technique for removing arsenic from aquatic environments but studies on the mechanisms of tolerance to this pollutant, when present in the form of arsenite (AsIII) still need to be performed. Thus, in order to evaluate the potential of Pistia stratiotes to phytoremediation of AsIII and the morphological and biochemical responses involved in metalloid tolerance, P. stratiotes plants were exposed to four treatments: 0 (control), 5, 10 and 20 µM AsIII, remaining under treatment for 24 h for biochemical analysis and for 4 days to analyze the arsenic (As) uptake, biomass production, bioconcentration factor (BCF), translocation factor (TF) and visual symptomatology. The plants were able to accumulate As in both roots and leaves. This accumulation was higher in the treatment with 10 µM AsIII (1120.40 and 31.60 µg g−1 dry weight in roots and leaves, respectively), decreasing in the following concentration. P. stratiotes also showed a high BCF, that was higher than 1000 when exposed to 5 and 10 µM AsIII (1808.38 and 1536.02, respectively). The pollutant was maintained mainly at the root (TF was always lower than 1.0) which may be a defense mechanism of aquatic plants to As. Despite the significant accumulation of pollutant, the plants were able to maintain growth in all evaluated concentrations, although in very different proportions. In fact, while in the lower concentration of As the biomass production was not affected, in the treatment with 20 μM AsIII the dry biomass decreased in approximately 77%. The accumulation of As resulted in the appearance of visual symptoms of toxicity such as chlorosis, darkening and reduction of the root system, which were more conspicuous in the highest As concentration. The metalloid exposition also triggered biochemical alterations, increasing the membrane damage and the reactive oxygen species (ROS) levels and, once again, these damages were more intense in the plants exposed to 20 μM AsIII. The action of the antioxidant system (especially in the leaves) and the compartmentalization of the pollutant in the root system apparently was important in the P. stratiotes response to toxic compounds and allowed the plants to maintain the cell homeostasis and the growth at the two lowest As concentrations. Thus, the data suggest that P. stratiotes may has a potential for phytoremediation of aquatic environments contaminated with AsIII concentrations close to 10 µM.

Cerrado is a Brazilian savannah ecosystem that has a high diversity of flora and fauna and originally covered 2 million km2, but in recent years more than 50% of its area has been converted to grain crops and pastures. The intensive grain production in Cerrado has been accompanied by an increase in pesticide and herbicide use, glyphosate is the most common. This may have implications for biodiversity loss that are still unknown. Seeking this understanding, we assessed biochemical changes in two native Cerrado plants species subjected to glyphosate. The aim of this study was to identify biomarkers in Pouteria torta and Alibertia edulis treated with glyphosate and evaluate their use as phytoindicators of the herbicide on the Cerrado vegetation. The plants were challenged with glyphosate [Roundup Transorb®, containing 480 g L−1 acid equivalent (a. e.)] in two independent experiments. In both, glyphosate was used at 0, 200, 400, and 800 g a. e. ha−1. The activities of the enzymes phenylalanine ammonia lyase (PAL), peroxidase (POX), polyphenol oxidase (PPO), and 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), as well as the concentrations of shikimic acid, phenolic compounds, amino acids, proteins, and malondialdehyde (MDA) were evaluated at 1 and 13 and at 1 and 72 days post-application in P. torta and A. edulis leaves, respectively. Glyphosate had reduced EPSPS activity and blocks the shikimate pathway in P. torta and A. edulis. Thus, this biochemical changes can be biomarkers of glyphosate in both native Cerrado plants. The activity of the PAL and PPO enzymes also showed this potential. Glyphosate caused leaf chlorosis and necrosis in P. torta, in addition, the concentrations of phenolic compounds, proteins, and amino acids were altered only in this species. Thus, concentrations of these cell compounds can be biomarkers of glyphosate stress in susceptible plants. The herbicide did not have the same effects on A. edulis. The changes in P. torta leaves occurred more quickly than in A. edulis. Thus, A. edulis plants may be used as a glyphosate biosensor. P. torta were susceptible and can be a phytoindicator of the herbicide. Its high sensitivity is useful for monitoring the initial effects of glyphosate on native Cerrado vegetation.

Antioxidant enzymes are important components in the defense against arsenic (As) stress in plants. Here, we tested the hypothesis that Salvinia molesta, an aquatic fern, counteracts the harmful arsenite (AsIII) effects by activating scavenging reactive oxygen species (ROS) enzymes. Thus, our objective was to investigate the role of the superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), and ascorbate peroxidase (APX) in S. molesta tolerance to AsIII and indicate the use of this plant in remediation of contaminated water. Plants were grown in nutrient solution at pH 6.5 and exposed to 0, 5, 10, or 20 µM AsIII for 96 h (analyses of As absorption, mineral nutrient content, and relative growth rate) and for 24 h (analyses of oxidative stress indicators and enzymatic antioxidant defenses). In the floating leaves, there was a greater basal activity of the antioxidant enzymes and less accumulation of As than in submerged leaves. The submerged leaves, which function as roots in S. molesta, accumulated more As than floating leaves, and SOD and CAT activities were inhibited. Thus, there was a greater production of ROS and oxidative stress. Our results show that S. molesta presents enzymatic antioxidant defenses to alleviate AsIII toxicity and are more effectives in the floating leaves. These results are important to elucidate the AsIII tolerance mechanisms in S. molesta and the possibility of their use in contamined water phytoremediation. Additional studies exposing plants to more prolonged stress and using AsIII concentrations closer to those found in contaminated environments will confirm this claim.

Made available in DSpace on 2021-06-25T10:16:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-01 Plants exposed to suboptimal temperatures suffer damage to physiological processes, growth, development and yield. Acting as enhancers of physiological and metabolic performance of plants, biostimulants have been used to mitigate crop damage caused by abiotic stresses. This study aimed to determine which formulation and dosage of FH Attivus® biostimulant have the best effects on the development of bean plants exposed to suboptimal temperatures (

Little is known about the role of light intensity in modulating plant responses to stress due to water deficit (WD). Thus, the objective of this study was to determine the WD and contrasting irradiance effects on the physiology, anatomy, and grain yield of soybean plants. The experimental design was a randomized block in a growth chamber and a 2 × 2 factorial treatment arrangement: 90% (well-watered, WW) and 40% (WD) of soil field capacities (FC); and 750 (medium irradiance, MI) and 1500 (higher irradiance, HI) μmol (photons) m-2 s-1 irradiance. The WD caused a lower photosynthetic rate - as well as observed in the light curve and in the relative parameters, such as apparent quantum efficiency -, less investment in shoot biomass and pollen grain germination, resulting in lower grain yield. However, there was an increase in non-photochemical energy dissipation, a higher concentration of total soluble sugars, proline, and malondialdehyde. The WD + MI-soybean plants developed thicker spongy parenchyma (related to higher mesophilic conductance of CO2 ). In the WW + HI condition the palisade parenchyma was thicker, conferring maintenance of photosynthetic efficiency. In addition, there was an increase in the activity of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase antioxidant enzymes in leaves due to HI, regardless of FC. This induced higher energy expenditure, reflected in the reduction of the number of leaf and branches, leaf area, dry mass of leaves and stem in the WW + HI. Interestingly, these strategies of osmotic adjustment, photoprotection, and antioxidant defenses act together in the WD + HI.

Drought is the most harmful environmental factor crop productivity. Some chemicals are used in agriculture to mitigate the damage from this stress on plants. Therefore, we examined whether the spraying of zinc sulfate (ZS), potassium phosphite (KPhi) and the hydrogen sulfide (H2S) donor sodium hydrosulfide (NaHS) would mitigate the deleterious effects of water deficit on sunflower plants by analyzing physiological and biometric characteristics. The experiment was carried out in a greenhouse using a randomized block design with five replications. The treatments were arranged in a 4 x 2 factorial scheme: [Factor A (Alleviators)] - spraying of KPhi (0.5 L ha-1), ZS (3.2 kg ha-1), NaHS (1.2 g ha-1), and water; [Factor B (substrate humidity, SH)] - 100% (well irrigated) and 30% (water deficit, WD) of field capacity. Under WD conditions, alleviators led to the maintenance of higher values of water potential (ΨW), a lower content of leaf malonaldehyde (MDA), and increased activity of the antioxidant enzyme peroxidase (POX), except for ZS. However, leaf osmotic potential, proline concentration, variables related to gas exchange and chlorophyll a fluorescence, and biometric characteristics differed only according to the SH factor. The results of ΨW and MDA for sunflower plants under WD are indicative of the mitigating capacity of ZS, KPhi, and H2S. Thus, the spraying of these compounds on sunflower plants mitigates the effects of WD, acting specifically in physiological processes related to antioxidant responses and in the maintenance of water in leaf tissues. RESUMO A seca é o fator ambiental que mais prejudica a produtividade das culturas. Alguns produtos químicos têm sido utilizados na agricultura para mitigar os danos causados por esse estresse nas plantas. Portanto, examinamos se a pulverização dos compostos sulfato de zinco (ZS), fosfito de potássio (FP) e doador de sulfeto de hidrogênio (H2S) - hidrossulfeto de sódio (NaHS) - mitigam os efeitos deletérios do déficit hídrico em plantas de girassol, analisando características fisiológicas e biométricas. O experimento foi conduzido em casa de vegetação sob delineamento de blocos ao acaso com cinco repetições. Os tratamentos foram arranjados em esquema fatorial 4 x 2: [Fator A (aliviadores)] - pulverização de FP (0.5 L ha-1), ZS (3.2 kg ha-1), NaHS (1.2 g ha-1), e água; [Fator B (umidade do substrato, US)] - 100% (bem irrigado) e 30% (déficit hídrico, DH) da capacidade de campo. Nas condições de DH, os aliviadores levaram à manutenção de maiores valores de potencial hídrico (ΨW), menor teor de malonaldeído foliar (MDA) e aumento da atividade da enzima antioxidante peroxidase (POX), exceto para ZS. Entretanto, o potencial osmótico foliar, a concentração de prolina, as variáveis relacionadas às trocas gasosas, fluorescência da clorofila a e as características biométricas diferiram apenas em função do fator US. Os resultados de ΨW e MDA em plantas de girassol sob DH são indicativos da capacidade mitigadora do ZS, FP e H2S. Assim, a pulverização desses compostos em plantas de girassol mitiga os efeitos do DH, atuando especificamente em processos fisiológicos relacionados a respostas antioxidantes e na manutenção de água nos tecidos foliares.

Made available in DSpace on 2021-06-25T10:16:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) To meet the growing demand for soybean it is necessary to increase crop yield, even in low water availability conditions. To circumvent the negative effects of water deficit, application of biostimulants with anti-stress effect has been adopted, including products based on fulvic acids and Ascophyllum nodosum (L.) seaweed extracts. In this study, we determined which formulation and dosage of a biostimulant is more efficient in promoting the recovery of soybean plants after stress due to water deficit. The experiment was conducted in a greenhouse, in a double-factorial randomized block design with two additional factors, four repetitions and eleven treatments consisting of three biostimulant formulations (F1, F2 and F3), and three dosages (0.25; 0.50 and 1.0 kg ha−1); a control with water deficit and a control without water deficit. Soybean plants were kept at 50% of the pot's water capacity for three days, then rehydrated and submitted to the application of treatments with biostimulant. After two days of recovery, growth, physiological, biochemical and yield parameters were evaluated. All plants that received the application of the biostimulant produced more than the water-stressed control plants. The biostimulant provided higher photosynthetic rates, more efficient mechanisms for dissipating excess energy and higher activities of antioxidant enzymes. Plants treated with biostimulant were more efficient in the recovery of the metabolic activities after rewatering, resulting in increased soybean tolerance to water deficit and reduced yield losses. The best result obtained was through the application of formulation 2 of the biostimulant at a dosage of 0.25 kg ha−1. Laboratory of Ecophysiology Applied to Agriculture School of Agricultural Sciences São Paulo State University (UNESP) Laboratory of Ecophysiology and Crop Production Federal Goianian Institute (IF Goiano), Campus Rio Verde Fertilizers Heringer Laboratory of Ecophysiology Applied to Agriculture School of Agricultural Sciences São Paulo State University (UNESP)

Common bean (Phaseolus vulgaris) cultivation occurs mainly in regions with acidic soils, where high aluminum (Al) concentration is a major constraint to crop production. In this study, we evaluated tolerance and sensitivity traits to Al exposure and calcium (Ca) deficiency in bean plants, and determined the efficiency of Ca to mitigate the toxic Al effects. Two bean cultivars (BRS Estilo and Campos Gerais) were grown in three soil conditions: (I) soil liming with calcium hydroxide Ca(OH)2 and Al unavailable (-Al+Ca); (II) fertilized soil with calcium nitrate [Ca(NO3)2·4H2O] and Al available (+Al+Ca); and (III) soil without Ca addition and Al available (+Al-Ca). At the beginning of the reproductive stage, we evaluated the photosynthetic processes, mineral nutrition, and leaf anatomy and morphological traits of plants. The photosynthetic parameters were good tools for monitor Al sensitivity in bean. +Al+Ca soil treatment mitigated the deleterious effects of Al on growth and mineral nutrition of both bean cultivars. However, Ca did not prevent the toxic effects of Al on leaf anatomy. Al stress and Ca deficiency caused negative effects on nutrient content, photosynthetic activity and leaf anatomy of bean plants. Calcium mitigated Al toxicity, primarily in the Campos Gerais cultivar, showing the potential to improve bean crop productivity in acid soils.

Weeds and microorganisms interacting with their rhizosphere may influence nutrient absorption, which is an important factor for plant competition. The purpose of this study was to evaluate the microbiological activity, inorganic phosphorus solubilization (Pi) and acid phosphatase in the cultivated soil, in a combination of soybean (Glycine max) plants and weeds. Soybeans were cultivated in monoculture and in competition with Bidens pilosa, Brachiaria decumbens (Syn. Urochloa decumbens) and Eleusine indica, under two conditions: a) plants competing without contact between the roots b) plants competing with contact between the roots. A nylon screen with a 50 µm mesh was added to prevent contact between the roots of the species in competition so that the substratum could be separated in the vase. The experiment was conducted in randomized blocks, with four replications. The soybeans in competition with weeds led to lower oxidation of organic matter per unit of microbial biomass, resulting in a lower metabolic quotient, compared with the soybean monoculture. The contact between soybean roots and B. pilosa, B. decumbens and E. indica maintained a strong influence, raising the solubilization of Pi, respectively valued at 51, 39 and 31% in relation to the cultivation of each species with a nylon screen. Microbiological activity, inorganic phosphorus solubilization and acid phosphatase were altered by plant species, combinations of weeds and soybean plants in competition; by root contact in some cases. Thus, the microbiological activity of the soil can influence competition strategies and plant development. RESUMO: As plantas daninhas e os microrganismos associados à sua rizosfera podem apresentar interações que influenciam na habilidade de absorção de nutrientes, fator importante em plantas em competição. Dessa forma, avaliou-se neste trabalho a atividade microbiana, o potencial de solubilização de fósforo inorgânico (Pi) e a atividade de fosfatases ácidas em solo cultivado com combinações de soja (Glycine max) e plantas daninhas. Para isso, cultivou-se a soja em monocultivo e em competição com Bidens pilosa, Brachiaria decumbens (Syn. Urochloa decumbens) e Eleusine indica, em duas condições de competição: a) sem contato entre raízes das espécies; e b) com contato entre raízes das espécies. Para evitar o contato entre raízes das espécies em competição, bem como separar o substrato em um mesmo vaso, utilizou-se uma tela de náilon de 50 µm de abertura. O experimento foi conduzido em blocos casualizados, com quatro repetições. A soja em competição com plantas daninhas reduziu a oxidação da matéria orgânica por unidade de biomassa microbiana, diminuindo o quociente metabólico, em comparação com a soja em monocultivo. O contato entre as raízes da soja e das espécies de plantas daninhas promoveu o aumento da solubilização de Pi em 51%, 39% e 31% para B. pilosa, B. decumbens e E. indica, respectivamente, em relação ao cultivo de cada espécie com a tela de separação. A atividade microbiana, a solubilização do Pi e a atividade de fosfatases ácidas foram alteradas pelas espécies de plantas e, pelas combinações de plantas daninhas e soja em competição, principalmente, quando houve contato entre raízes. Assim, a atividade microbiológica do solo pode influenciar nas estratégias de competição e desenvolvimento das plantas.

The objective of this work was to evaluate the effects of drought stress in the reproductive stage (R3) on the physiological parameters and grain yield of two soybean (Glycine max) lines. The Vx-08-10819 and Vx-08-11614 soybean lines were grown in a greenhouse, where they were irrigated until they reached the R3 development stage. During three days, the weight of the pots was monitored daily in order to maintain 100, 60, and 40% field capacity (control and moderate and severe stress, respectively). The parameters gas exchange and chlorophyll a fluorescence, as well as chloroplast pigments, osmoregulatory solutes and antioxidant enzymes, were determined. After stress, the plants were rehydrated until the end of the reproductive stage (R8), to evaluate grain yield. Vx-08-10819 showed traits that contributed to drought tolerance, such as better water-use efficiency, modulation of leaf area, and enzymatic activity, as well as a more efficient photosynthetic apparatus and a lower lipid peroxidation rate than Vx-08-11614. In addition, Vx-08-10819 maintained its productivity even after the severe water deficit. By contrast, water limitations affected negatively the productivity of Vx-08-11614. The Vx-08-10819 soybean line can efficiently withstand drought periods during the reproductive stage, without any interferences on final grain yield. Resumo: O objetivo deste trabalho foi avaliar os efeitos do estresse hídrico no estádio reprodutivo (R3) sobre os parâmetros fisiológicos e o rendimento de grãos de duas linhagens de soja (Glycine max). As linhagens de soja Vx-08-10819 e Vx-08-11614 foram cultivadas em casa de vegetação, onde foram irrigadas até atingirem o estágio de desenvolvimento R3. Durante três dias, o peso dos vasos foi monitorado diariamente para manter 100, 60 e 40% da capacidade de campo (controle e estresses moderado e severo, respectivamente). Foram determinados os parâmetros trocas gasosas e fluorescência da clorofila a, além dos pigmentos cloroplastídicos, solutos osmorregulatórios e enzimas antioxidantes. Após o estresse, as plantas foram reidratadas até o final do estádio reprodutivo (R8) para avaliar o rendimento de grãos. Vx-08-10819 apresentou características que contribuíram para a tolerância à seca, como melhor eficiência no uso da água, modulação da área foliar e atividade enzimática, bem como aparato fotossintético mais eficiente e menor peroxidação lipídica que Vx-08-11614. Além disso, Vx-08-10819 manteve sua produtividade mesmo após deficiência hídrica severa. Em contraste, as limitações hídricas afetaram negativamente a produtividade de Vx-08-11614. A linhagem de soja Vx-08-10819 pode suportar eficientemente períodos de seca durante o estádio reprodutivo, sem que haja interferência no rendimento final de grãos.

Native Cerrado plants are exposed to soils with low pH and high availability of Al. In this study, we measured the Al content in adult plants, and investigated the effects of various Al doses on germination and early development of Eugenia dysenterica plants. For germination tests, the seeds were soaked in Al solution and evaluated for twenty days in growth chambers. In a second experiment, young plants were cultivated in hydroponic systems with various Al concentrations to evaluate the morphological, anatomical and physiological characteristics of E. dysenterica. Anatomical changes and low germinative vigor were observed in seeds germinated in 600 and 800 μmol Al3+ L−1. In the hydroponic system, 200 μmol Al3+ L−1 stimulated root growth in young plants. The activity of antioxidant enzymes and the accumulation of phenolic compounds were greatest at the highest Al doses, preventing changes in gas exchange and chlorophyll a fluorescence. Starch grain accumulation was noted in plant cells exposed to 200 and 400 μmol Al3+ L−1. Adult E. dysenterica trees also accumulated Al in leaves, bark and seeds. These data suggest that E. dysenterica is tolerant to Al.

As an alternative to control of resistant biotypes, farmers have resorted to the use of herbicides that have residual soil activity and good pre-emergence action. One of the most used mixtures in Brazil is that of sulfentrazone + glyphosate. When a herbicide has a pre-emergence action, small leaching of its molecules is necessary for its superficial incorporation into the soil, where most of the weed seeds are found. However, if excessive leaching occurs, the herbicide may have reduced efficiency in controlling weed, increasing the risks of groundwater contamination. In this study, sulfentrazone leaching was evaluated in columns with soil, in isolated applications and in mixture with formulations of glyphosate (Roundup Ready®, Roundup Ultra® and Zapp Qi®). For this, the columns were filled with samples of Red-Yellow Latosol, collected in the 0-20 cm depth layer. After moistening the columns to near field capacity, the herbicides were applied to the top and, 24 hours later, a 60 mm rainfall was simulated. After 72 hours, the columns were sectioned in 5 cm segments, collecting the soil from each segment. In these samples, indicator plants (Sorghum bicolor) were cultivated for the presence of the herbicide. It is concluded that, in general, glyphosate does not alter the leaching potential of sulfentrazone in the Red-Yellow Latosol. However, mixtures with Roundup Ready® and Zapp Qi® reduce the sorptive forces of sulfentrazone to soil colloids. Therefore, in some types of soil, herbicide desorption may occur with greater intensity, making its availability in the soil solution more difficult. This may result in better control of plants and/or intoxication of sensitive crops. RESUMO: Como alternativa de controle de biótipos resistentes, os agricultores têm recorrido ao uso de herbicidas que possuem atividade residual no solo e têm boa ação em pré-emergência. Uma das misturas mais utilizadas no Brasil é a de sulfentrazone + glyphosate. Quanto um herbicida tem ação em pré-emergência, pequena lixiviação de suas moléculas é necessária para sua incorporação superficial no solo, onde se encontram a maioria das sementes das plantas daninhas. No entanto, ocorrendo lixiviação excessiva, o herbicida pode ter sua eficiência no controle das plantas daninhas reduzida, aumentando os riscos de contaminação do lençol freático. Neste trabalho foi avaliada a lixiviação do sulfentrazone, em colunas com solo, em aplicações de forma isolada e em mistura com formulações de glyphosate (Roundup Ready®, Roundup Ultra® e Zapp Qi®). Para isso, as colunas foram preenchidas com amostras de Latossolo Vermelho-Amarelo, coletadas na camada de 0-20 cm de profundidade. Após umedecimento das colunas, até próximo à capacidade de campo, aplicaram-se os herbicidas no topo e, 24 horas depois, foi simulada chuva de 60 mm. Após 72 horas, as colunas foram seccionadas em segmentos de 5 cm, coletando-se o solo de cada segmento. Nessas amostras foram cultivadas plantas indicadoras (Sorghum bicolor) da presença do herbicida. Conclui-se que, em geral, o glyphosate não altera o potencial de lixiviação do sulfentrazone no Latossolo Vermelho-Amarelo. No entanto, as misturas com Roundup Ready® e Zapp Qi® reduzem as forças sortivas do sulfentrazone aos coloides do solo. Em razão disso, em alguns tipos de solo poderá ocorrer com maior intensidade a dessorção do herbicida, tornando maior a sua disponibilidade na solução do solo. Isso poderá resultar em melhor controle das plantas e/ou intoxicação das culturas sensíveis.

The great diversity of plant species in pastures of the Brazilian Cerrado with distinct ecophysiological characteristics indicates the possibility of finding, in the cellular content of this flora, chemical compounds with potential for use in agriculture and human and animal health. Three steps are necessary to prove this hypothesis: phytochemical prospecting, characterization of secondary metabolites, and studies on the biological activities of these metabolites present in these plants. The chemical profile of secondary metabolites present in five species of the Brazilian Cerrado (Davilla elliptica, Remijia ferruginea, Luehea paniculata, Anacardium occidentale, and Acosmium dasycarpum) was traced in this research. These plant species were collected in pasture areas of Felício dos Santos, Minas Gerais. The samples were dried and submitted to two types of extract (ethanolic and hexanic). By using specific chemical reactions, the presence of coumarins, triterpenes/steroids, and anthracenosides was observed in the hexanic extracts, while the presence of alkaloids, triterpenes/steroids, flavonoids, tannins, reducing compounds, and anthocyanins was observed in the ethanolic extracts. The species presented diverse classes of compounds. However, triterpenes/steroids, tannins, reducing compounds and anthocyanins were found in all species, being the use of the solvent ethanol the most efficient in extracting the compounds. The species D. elliptica presented the highest number of classes of compounds. The widespread application in folk medicine justifies further studies on the biological activity of different metabolites in agriculture and health areas.

Tembotrione is registered in Brazil for maize and is used in large areas of the country in each harvest. In recent years, producers have reported carryover effects of this herbicide in succeeding crops to maize. This fact can be attributed to tembotrione recommendations without knowing their interactions with tropical soils colloids. In this study, using high-performance liquid chromatography, it was possible to evaluate the influence of chemical and physical attributes on the sorption and desorption of tembotrione, as well as its metabolite AE 1417268, on seven soils from different regions of Brazil. The coefficients referring to sorption and desorption, as well as the hysteresis index (Kf, 1/n and H) of tembotrione and its metabolite were influenced by pH, clay content and organic matter. In soil samples with low levels of clay and organic matter, values of sorption coefficients were reduced as pH increased. The desorption of tembotrione and its metabolite in all soils were low, mainly in the clayey ones and in soils with higher organic matter content. The sorption of tembotrione and its metabolites varies with the attributes of soil, presenting a direct relation with clay and organic matter contents and an inverse one with soil pH. The desorption of tembotrione and its metabolite decreased with the increase in clay and organic matter contents in the evaluated soils.

The hormesis effect of 2,4-D, applied at two stages of soybean development, on the physiological components of crop yield, was investigated. Soybean seeds of the cultivar ‘AG 3680 IPRO’ were sown in pots containing 7 L of a substrate and kept in a greenhouse. A randomized complete block design with four replicates was used. Eighteen treatments were tested, arranged in a split-plot scheme. The plots consisted of two stages of herbicide application (V4 and V6), and the split-plots were arranged by nine 2,4-D doses (0, 5, 10, 15, 20, 25, 30, 40, and 50 g ha-1). At the time of harvest, 100 days after sowing, significant interactions between crop development stages and 2,4-D doses were observed for the number of nodes in the main stem (NNMS) and the number of pods per plant (NPP). Both NNMS and NPP were not affected by 2,4-D during V6, but they increased with doses up to 20.2 g ha-1 and 22.5 g ha-1, respectively, during V4 and declined at higher doses according to a quadratic model, thus characterizing hermetic effect. Regardless of the application stage, the number of grains per plant and weight of a thousand grains were reduced as doses increased. However, the grain number and grain mass per plant reached maximum values for doses of 20.3 g ha-1 and 12.9 g ha-1, respectively. It was concluded that 2,4-D causes hormesis effects on the soybean crop ‘AG 3680 IPRO’ pot-grown in greenhouse conditions, regardless of the application stages herein tested. RESUMO: Investigou-se o efeito hormético do 2,4-D, aplicado na soja em dois estádios de desenvolvimento, sobre os componentes fisiológicos de produtividade da cultura. Sementes de soja da variedade ‘AG 3680 IPRO’ foram semeadas em vasos contendo 7 L de substrato, mantidos em casas de vegetação. Foram avaliados 18 tratamentos no delineamento em blocos casualizados, com quatro repetições, dispostos em esquema de parcelas subdivididas. As parcelas foram constituídas por dois estádios de desenvolvimento (V4 e V6), e as subparcelas, por nove doses de 2,4-D (0, 5, 10, 15, 20, 25, 30, 40 e 50 g ha-1). Na colheita, aos 100 dias após a semeadura, verificou-se interação significativa entre estádio e dose de 2,4-D para o número de nós na haste principal (NNHP) e para o número de vagens por planta (NDV). O NNHP e o NDV não foram afetados pelo 2,4-D em V6, mas em V4 eles aumentaram até as doses de 20,2 g ha-1 e 22,5 g ha-1, respectivamente, segundo modelo quadrático, declinando em doses maiores, conferindo o efeito hormético. Independentemente do estádio de aplicação, o número de grãos por vagem e o peso de mil grãos reduziram-se com o aumento da dose. Todavia, o número de grãos e a massa de grãos por planta atingiram valores máximos para as doses de 20,3 g ha-1 e 12,9 g ha-1, respectivamente. Concluiu-se que o 2,4-D promove hormese na cultura da soja ‘AG 3680 IPRO’, cultivada em vasos em casa de vegetação, independentemente dos estádios de aplicação testados.

Before recommending an herbicide, it is necessary to know its interactions with the soil attributes that will influence its sorption and half-life in the soil. This knowledge is an essential condition for minimizing any negative effects that may result from its application. However, due to the great diversity of soil and climate in Brazil, especially for products of recent use in the country, such as the herbicide tembotrione, this knowledge is often not available. This may be the main cause of occurrence of intoxication reports in crops carried out in succession to corn sprayed with this herbicide. In order to reduce possible impacts on successor crops and the contamination of surface and groundwater using the high-performance liquid chromatography, the tembotrione half-life was determined in soils with different attributes. The evaluated soils were a Red-Yellow Latosol with and without liming (Viçosa, MG), Red-Yellow Latosol (Rio Paranaíba, MG), Yellow Latosol (Sooretama, ES), and Red-Yellow Latosol with and without liming (Gurupi, TO). The results showed that liming might favor tembotrione degradation in the soil, as well as direct relationships between values of tembotrione half-life and contents of clay and soil organic matter. Tembotrione half-life in samples of Red-Yellow Latosol (without liming) collected in Viçosa and Rio Paranaíba, MG, was higher than 90 days, indicating carryover risks in successive crops to corn sprayed with tembotrione in these regions.

Available information on physical compatibility and stability of pesticide mixtures is scarce and often divergent. This knowledge is of fundamental importance in the success of pest, disease, and weed control programs. Compatibility and stability of two glyphosate formulations (WG and SL) in a mixture with fluazinam + deltamethrin + trifloxystrobin/cyproconazole at four diluted water concentrations and different times were evaluated under laboratory conditions. The evaluations were performed at the following time intervals: immediately after mixing and 1, 5, 10, 30, 120, 900, and 1,440 minutes after the mixing of pesticides. Scores were assigned on a scale ranging from 1 to 5, where 1 meant immediate separation of compounds and 5 the perfect mixture stability up to 30 minutes. The data were submitted to descriptive statistics and presented in tables. Mixture stability differed in glyphosate formulations and their concentrations due to the used spray solution volume. Distinct mixtures between glyphosate (SL) and deltamethrin, as well as between glyphosate (WG) and deltamethrin, were physically compatible when stirred again even after 24 hours at rest. The mixture containing glyphosate (SL), deltamethrin, and fluazinam and trifloxystrobin/ cyproconazole was incompatible at a volume of 30 L ha-1. RESUMO: As informações disponíveis sobre compatibilidade física e estabilidade de misturas de agrotóxicos são escassas e muitas vezes divergentes. Esse conhecimento é de fundamental importância no sucesso de programas de controle de insetos-praga, doenças e plantas daninhas. Nesta pesquisa foi avaliada, em condições laboratoriais, a compatibilidade e estabilidade de duas formulações de glyphosate (WG e SL) em mistura com fluazinam + deltametrina + trifloxistrobina/ciproconazol, todas em quatro concentrações diluídas em água e em tempos variáveis. As avaliações foram feitas nos intervalos de tempo assim descritos: imediatamente após a mistura; 1; 5; 10; 30; 120; 900; e 1.440 minutos após a mistura dos agrotóxicos. Atribuíram-se notas em uma escala variando de 1 a 5, em que 1 significava separação imediata dos compostos, e 5, estabilidade perfeita da mistura até os 30 minutos. Os dados foram submetidos à estatística descritiva e apresentados em forma de tabelas. A estabilidade das misturas diferiu quanto às formulações do glyphosate e suas concentrações, em razão do volume de calda a ser utilizado. As misturas distintas entre o glyphosate (SL) e o inseticida deltametrina, bem como entre o glyphosate (WG) e o inseticida deltametrina, apresentaram-se compatíveis fisicamente quando agitadas novamente, mesmo após 24 horas em repouso. A mistura contendo glyphosate (SL), o inseticida deltametrina e os fungicidas fluazinam e trifloxistrobina/ciproconazol foi incompatível no volume de 30 L ha-1.

The characterization of sorption-desorption for imazethapyr and imazapic in six agricultural soils was performed to assess the availability of these herbicides in pollution processes. In this pursuit, the batch equilibrium method and high-performance liquid chromatography were used. The magnitude of Kf values ranging from 0.38 to 2.52 mg1-n kg-1 Ln for imazethapyr and 0.43 to 2.72 mg1-n kg-1 Ln for imazapic indicate weak sorption in the evaluated soils. Soil pH (5.1 to 6.1) and iron oxalate affect sorption-desorption of both herbicides but the type and percentage of clay can be the main factor affecting these two processes. A high desorption percentage (>70%) was found in Regosol, Dystric Plinthosol, Ferralsol (for both herbicides), and Dystric Gleysol (only imazapic) soils, which implies in leaching risks of these imidazolinone herbicides into groundwater. Lower desorption (70%) foi encontrada nos solos Entissolo, Plintossolo Distrófico, Latossolo Vermelho-Amarelo (para ambos os herbicidas) e Gleissolo Distrófico (somente imazapic), o que implica em riscos de lixiviação desses herbicidas imidazolinonas para águas subterrâneas. A dessorção mais baixa (

The commercial mixture of imazethapyr and imazapic herbicides has been used for the control of red rice and several other species of weeds found in rice crops; this system called Clearfield. However, its use may limit the succession of non-tolerant crops for long residual activity. The research objective with this work was to determine the persistence of imazethapyr, imazapic and their mixture in three soils in the Brazilian state of Tocantins. Three experiments were conducted in a completely randomized design with four replications, each corresponding to the evaluated soil (Haplic Plinthosol (FX), red-yellow Latosol (LVA) and Haplic Gleysol (GX)). The treatments were arranged in a split plot design, with the allocated plots herbicides (imazethapyr and imazapic alone and commercial mixture) and the plots allocated the 11 evaluation times (1, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150 days after treatment (DAT)), and a control without application. Contacted up long residual effect of imazethapyr and commercial mixture of imazethapyr and imazapic, regardless of assessed soil. After 150 days of applying herbicides or the commercial mixture, their residues in the soil also inhibited approximately 94% of the mass of the dry matter accumulation of the indicator plants. When imazapic was applied alone, there was a higher dry matter accumulation of the indicator plants, indicating less residual effect of this herbicide in the soil and this was attributed to the lower dose of this herbicide applied. The attributes of the soil pH, texture and iron oxides were what most affected the persistence of the herbicides. It can be concluded that the persistence of imazethapyr and imazapic is too long in the Brazilian state of Tocantins soils and the use of these herbicides in the region should be avoided due to the high risk of the occurrence of carryover,or be well planned, as land use in rotation for susceptible crops. RESUMO O sistema de cultivo Clearfield(r) utiliza os herbicidas imazethapyr e imazapic no controle de plantas daninhas. Um dos principais problemas relacionados ao uso desse sistema é a restrição ao cultivo de outras culturas, causada pelo efeito residual dos herbicidas. Três experimentos foram realizados para avaliar a persistência do imazethapyr e imazapic em solos utilizados no sistema Clearfield(r). Cada experimento correspondeu a um solo avaliado: Plintossolo Háplico, Latossolo Vermelho-Amarelo ou Gleissolo Háplico. O imazethapyr e o imazapic isolados e em mistura comercial foram aplicados no solo, e seu residual foi avaliado em 11 épocas (1, 15, 30, 45, 60, 75, 90, 105, 120, 135 e 150 dias após o tratamento). A planta indicadora utilizada foi o sorgo (Sorghum vulgare). O imazethapyr e sua mistura com o imazapic causaram reduções da matéria seca das plantas indicadoras superiores a 94%, mesmo após 150 dias da aplicação, independentemente do solo avaliado. O imazapic causou menor inibição do crescimento do sorgo, indicando menor efeito residual desse herbicida nos solos. A mistura comercial teve maior persistência, comparada à aplicação isolada dos herbicidas. Independentemente do tipo de solo, a persistência do imazethapyr foi maior que a do imazapic.

Knowledge of herbicides sorption by colloids predicts its movement in the soil profile and its effectiveness in controlling weeds and crops poisoning when directly applied to the soil. This knowledge becomes even more important for herbicides which have long persistence in the soil. In this research, clomazone sorption was estimated by the biological method in Brazilian soil samples with different physical and chemical characteristics, cultivated with sugarcane crops. As an indicator of the presence of clomazone in the soil, Sorghum bicolor was used. The data relating to assessments of poisoning and accumulation of dry matter of the plants were subjected to multivariate analysis of similarity among variables. After that, clomazone doses that caused 50% of intoxication in sorghum plants grown (C50) as well as sorption ratio (SR) of the herbicide in different soil types were estimated. There was similarity greater than 80% for data regarding the percentage of intoxication and accumulated dry matter, with the option to use only those related to the first variable. RS and C50 were higher in Organosol and lower in red-yellow Latosol with and without changing the pH. It was concluded that the clomazone dose to be recommended must be differentiated for different soils, since the value of clomazone sorption in the soil is dependent on its attributes, and the organic matter content is of the utmost importance. RESUMO O conhecimento da sorção de herbicidas pelos coloides permite prever a sua movimentação no perfil do solo, além de sua eficiência no controle das plantas daninhas e da intoxicação de culturas, quando aplicado diretamente no solo. Esse conhecimento torna-se ainda mais importante para os herbicidas que apresentam longa persistência no solo. Nesta pesquisa foi estimada, por método biológico, a sorção do clomazone em amostras de solos brasileiros com diferentes características físicas e químicas, cultivados com a cultura da cana-de-açúcar. Como indicador da presença do clomazone no solo foi utilizado Sorghum bicolor. Os dados obtidos referentes às avaliações da intoxicação e ao acúmulo de matéria seca das plantas foram submetidos a análise multivariada de similaridade entre as variáveis. Após isso, foram estimadas as doses do clomazone que causaram 50% de intoxicação nas plantas de sorgo cultivadas (C50) e, também, a relação de sorção (RS) do herbicida nos diferentes tipos de solo. Verificou-se similaridade superior a 80% para os dados referentes a porcentagem de intoxicação e matéria seca acumulada, optando-se por utilizar apenas aqueles relativos à primeira variável. A RS e a C50 foram maiores no Organossolo e menores no Latossolo Vermelho-Amarelo com e sem alteração do pH. Concluiu-se que a dose do clomazone a ser recomendada deve ser diferenciada para solos distintos, pois o valor da sorção do clomazone no solo é dependente de seus atributos, sendo o teor de matéria orgânica o de maior importância.

The objective of this study was to evaluate the weed community in a raw sugarcane renovation area with three soil managements and peanut sowing in succession. The experiment was conducted during the 2007/08 season on a raw sugarcane area harvested without prior burning in the last five cuts. A randomized block design with treatments arranged in a split plot and arranged in four replications was used. The main treatments consisted of three cropping systems: conventional tillage, minimum tillage and direct planting, and subplots consisted in the absence (resting) or presence of crop rotation with peanuts. After 135 days from planting peanuts and 180 days of sugarcane harvest, the number of weeds m-2 was counted and the shoot dry biomass of the weeds collected was determined. The data were interpreted by analysis of variance and the means were compared by Tukey's test at 5% probability so that phytosociological indices a, b, c e d were calculated. The use of soil conservation tillage and peanut in rotation with sugarcane in the renovation areas is effective in controlling weeds and suppression of weed species difficult to control like Cyperus rotundus, Commelina bengalensis, Urochloa plantaginea, and Digitaria nuda. Acredita-se ser possível reduzir o custo com o controle de plantas daninhas em áreas de reforma de cana crua adotando-se sistemas de manejos adequados. Objetivou-se com este trabalho avaliar a comunidade infestante em área de reforma de cana crua submetida a diferentes manejos. Nesta pesquisa, utilizando-se uma área de um canavial colhido sem queima prévia, nos últimos cinco cortes foram avaliados três sistemas de cultivo: convencional, mínimo e plantio direto, associados ao pousio e cultivo do amendoim. Após 135 dias da semeadura do amendoim e 180 dias da colheita da cana-de-açúcar, foi feita a contagem do número de plantas daninhas por meetro quadrado e da matéria seca da parte aérea das plantas daninhas coletadas. Todos os dados obtidos foram analisados estatisticamente. Para interpretação dos resultados, utilizou-se o teste de Tukey a 5% de probabilidade e valores dos índices fitossociológicos a, b, c e d calculados. Conclui-se que a utilização do sistema de plantio direto associado ao cultivo do amendoim em rotação com a cana-de-açúcar em áreas de cana crua favorece o controle e a supressão de espécies de plantas daninhas de difícil controle, como Cyperus rotundus, Commelina benghalensis, Urochloa plantaginea e Digitaria nuda.

RESUMO O conhecimento dos fatores que influenciam a lixiviação dos herbicidas no solo é fundamental para sua utilização de forma segura, do ponto de vista técnico e ambiental. Neste trabalho, avaliou-se a mobilidade do sulfentrazone em quatro solos provenientes de uma área de reflorestamento da região Sul do Brasil (Planossolo Háplico, Argissolo Vermelho, Cambissolo Húmico e Neossolo Regolítico) e um Latosso Vermelho-Amarelo da Zona da Mata de Minas Gerais. As amostras de solo foram coletadas na profundidade de 0-20 cm e caracterizadas física e quimicamente. Os substratos foram colocados em colunas e, posteriormente, aplicou-se, nos topos delas, 1,0 kg ha-1 do herbicida, seguido de uma chuva simulada de 60 mm. Após a drenagem da água, foram semeadas ao longo da coluna sementes da espécie Sorghum bicolor , como planta bioindicadora da presença do sulfentrazone; 21 dias após o plantio, foi realizada a avaliação visual da intoxicação das plantas de sorgo e a coleta da parte aérea delas para determinação da matéria seca. O delineamento utilizado foi o inteiramente casualizado, em esquema de parcelas subdivididas. As colunas preenchidas com cada um dos solos constituíram as parcelas, e as 10 profundidades da coluna (0-5, 5-10, 10-15, 15-20, 20-25, 25-30, 30-35, 35-40, 40-45 e 45-50 cm), as subparcelas, mais uma testemunha sem herbicida para cada solo. Os teores de argila e matéria orgânica e o pH de cada solo influenciaram na mobilidade do sulfentrazone; solos com menores teores de argila e matéria orgânica apresentaram maior potencial de lixiviação desse herbicida. ABSTRACT Knowledge of factors that influence the leaching of herbicides in the soil is essential to use these products safely from a technical and environmental perspective. This study evaluated the mobility of sulfentrazone in four soils from southern Brazil (Haplic Planosol, Red Argisol, Humic Cambisol and Entisol) and a Red-Yellow Latosol from the Zona da Mata region in the state of Minas Gerais. Soil samples were collected at a depth of 0-20 cm and characterized physically and chemically. The substrates were placed in columns, and 1 kg ha-1 of the herbicide was subsequently applied on top of them, followed by a simulated rainfall of 60 mm. After draining the water, Sorghum bicolor seeds were sown along the column, as bioindicators of the presence of sulfentrazone; 21 days after planting, the presence of the sorghum plants was assessed visually, and the shoots were collected for determination of dry matter. The experimental design was completely randomized in subdivided plots, whereas the columns filled with each of the five soils were the main plots and the 10 column depths (0-5, 5-10, 10-15, 15-20, 20-25, 25-30, 30-35, 35-40, 40-45 and 45-50 cm) were the subplots. There was a herbicide-free control for each soil. Clay content, organic matter and pH of each soil influenced the mobility of sulfentrazone, and soils with lower clay and organic matter levels showed higher potential of leaching of sulfentrazone.

Currently, biomonitoring is a methodology used to verify the environmental impact of new technologies in the agricultural environment, highlighting edaphic entomofauna that is traditionally used as a bioindicator in this sort of research. Therefore, the objective of this study was to investigate the edaphic entomofauna variation depending on glyphosate application in Roundup Ready soybeans. The experiment was carried out in Coimbra, MG during the 2007/2008 and 2008/2009 cropping seasons. The experimental design was a randomized block design with five replications. The treatments were: non-transgenic soybean with mechanical weeding of weeds; transgenic soybean with mechanical weeding of weeds; transgenic soybean with one glyphosate application and transgenic soybean with three glyphosate applications. The populations of the edaphic entomofauna were sampled during two crops. The insertion of the glyphosate tolerance gene did not affect the richness and the abundance of arthropods in the soil. The arthropod richness was reduced in treatments where glyphosate was applied one and three times. The glyphosate application in transgenic soybean reduced the density of the predatory mite Galumnidae (Acari); predator ants Neivamyrmex sp. (Hymenoptera: Formicidae) and Solenopsis sp. (Hymenoptera: Formicidae); and springtails Entomobryidae (Collembola), Hypogastrura sp. (Collembola: Hypogastruridae) and Onychiuridae (Collembola). Therefore, it is essential to follow the use recommendations of the herbicide glyphosate and adopt good agricultural practices that promote pesticide biodegradation, thereby contributing to the reduction of the toxicological potential of glyphosate on the edaphic entomofauna. RESUMO: Atualmente, o biomonitoramento tem sido uma metodologia bastante adotada para se verificar o impacto ambiental das novas tecnologias no meio agrícola, com destaque para a entomofauna edáfica, que é tradicionalmente utilizada como bioindicadora nesse tipo de pesquisa. Assim, objetivou-se com este estudo investigar a variação da entomofauna edáfica em função da aplicação do herbicida glyphosate em cultivos de soja Roundup Ready. O experimento foi realizado em Coimbra, MG, nas safras agrícolas de 2007/2008 e 2008/2009. Utilizou-se o delineamento experimental em blocos casualizados com cinco repetições. Os tratamentos estudados foram: soja não transgênica com capina mecânica das plantas daninhas; soja transgênica com capina mecânica das plantas daninhas; soja transgênica com uma aplicação de glyphosate; e soja transgênica com três aplicações de glyphosate. As populações da entomofauna edáfica foram amostradas ao longo dos dois cultivos. A inserção do gene de tolerância ao herbicida glyphosate não afetou a riqueza e a abundância de artrópodes do interior do solo. A riqueza dos artrópodes foi reduzida nos tratamentos que receberam uma e três aplicações de glyphosate. A aplicação de glyphosate na soja transgênica reduziu a densidade do ácaro predador Galumnidae (Acari); das formigas predadoras Neivamyrmex sp. (Hymenoptera: Formicidae) e Solenopsis sp. (Hymenoptera: Formicidae); e dos colêmbolos Entomobryidae (Collembola), Hypogastrura sp. (Collembola: Hypogastruridae) e Onychiuridae (Collembola). Diante disso, torna-se essencial atender às recomendações de uso do herbicida glyphosate e adotar boas práticas culturais que favoreçam a biodegradação de pesticidas, para assim contribuir com a redução do potencial toxicológico do glyphosate sobre a entomofauna edáfica.

In Brazil, sugarcane is grown in large areas. Weed control in sugarcane fields is done by chemical method, since it is more efficient and less expensive. In this method, herbicides that persist in the environment for long periods are used, among which there are hexazinone and diuron, which are applied in mixtures marketed by the industry. This research evaluated the sorption and desorption of hexazinone and diuron applied alone and in mixture, in two samples of Red-Yellow Latosols (LVAG and LVAV) and a Organosol (OR), with and without manure. Sorption isotherms were built using the batch equilibrium method and the identification and quantification of herbicides was obtained through a high-performance liquid chromatography (HPLC) with UV-Vis detector. There were high diuron sorption coefficients (Kf) in the soils. The hexazinone Kf values found were low in LVAG and LVAV soils, and they were high ground only in OR. In all soils, diuron and hexazinone showed higher Kf values when mixed. There was a direct relation between the addition of manure to the substrate and the Kf values . Higher desorption values (Kfd) in relation to those of sorption in LVAG and LVAV soils indicate gradual release of these herbicides in the soil solution when using organic fertilizer, showing increased sorption and desorption of these molecules; this is accentuated when they are mixed. In the Organosol, desorption was very low, and cannot be quantitated by the used method. It is possible to conclude that the incubation of LVAG and LVAV soil with manure helps both the process of sorption and desorption of herbicides. However, sorption and desorption in the Organosol is high indicating very low agrochemicals such strong bonds with soil colloids. RESUMO: No Brasil, a cana-de-açúcar é cultivada em extensas áreas. O controle das plantas daninhas nos canaviais é feito pelo método químico, pois é mais eficiente e de menor custo. Neste método são utilizados herbicidas que persistem no ambiente por longos períodos. Dos produtos recomendados para a cultura, os mais utilizados são o diuron e o hexazinone, aplicados isoladamente ou mistura comercializada pela indústria. Nesse sentido, o objetivo deste estudo foi avaliar a sorção e dessorção do hexazinone e do diuron, aplicados de forma isolada e em mistura, em duas amostras de Latossolo Vermelho-Amarelo (LVAG e LVAV), com e sem adição de esterco, e em um Organossolo (OR) sem adição de esterco. Primeiramente, foi determinado o tempo de equilíbrio dos herbicidas no solo pelo método batch equilibrium, e a identificação e quantificação dos herbicidas foram feitas por cromatografia líquida de alta eficiência (HPLC); em seguida, determinaram-se as isotermas de sorção e dessorção. Observaram-se elevados coeficientes de sorção (Kf) do diuron nos solos estudados. Os valores de Kf do hexazinone encontrados foram baixos nos solos LVAG e LVAV e elevados apenas no solo OR. Em todos os solos, o diuron e o hexazinone apresentaram valores de Kf maiores quando em mistura. Ocorreu relação direta entre a adição de esterco ao substrato e os valores do Kf. Maiores valores de dessorção (Kfd) em relação aos da sorção nos solos LVAG e LVAV indicam liberação gradual desses herbicidas na solução dos solos quando se fazem adubações orgânicas, indicando o aumento da sorção e dessorção dessas moléculas, acentuando-se quando em mistura. No Organosolo, a dessorção foi muito baixa e não pôde ser quantificada pelo método utilizado. Conclui-se que a aplicação da mistura diuron+hexazinone aumenta a sorção desses herbicidas ao solo. A recomendação do hexazinone isolado deve levar em consideração o teor de matéria orgânica do solo (MOS). O diuron em aplicação isolada apresenta alta sorção no solo. A dessorção apresenta alta magnitude em relação à sorção nos solos com baixo teor de MOS. No OR, a dessorção é baixa e por isso não pôde ser quantificada. Existe relação direta entre a adição de esterco ao substrato e a sorção nos solos. A incubação dos solos de baixo teor de MOS com esterco favorece tanto o processo de sorção quanto o de dessorção dos herbicidas.

Studies on herbicide behavior in soils may be performed using biological and chemical methods. The efficiency of the biological method depends on the indicator species sensitivity to low herbicide concentrations in the soil solution. Among the herbicides commonly used in Brazil for corn cultivation, tembotrione stands out. In the last agricultural seasons, the intoxication of some crops when cultivated in succession to corn has been reported, which may be attributed to tembotrione recommendations without the knowledge of their interactions with colloids of tropical soils. In this research, we selected an indicator plant species of tembotrione residues in the soil after sorting 12 species. The sorption of this herbicide was estimated in two Oxisols (Latossolo Amarelo and Latossolo Vermelho-Amarelo, Brazilian Soil Classification) and in a Histosol (Organossolo, Brazilian Soil Classification) with different attributes. Initially, after sorting the 12 plant species, the two most efficient in detecting tembotrione in the soil were selected. In the second stage, the most sensitive species was selected. In the third stage, tembotrione sorption was assessed in the three soils by using the selected species. Among the 12 species, Beta vulgaris and Brassica oleracea var. capitata were the most efficient in detecting tembotrione at low concentrations in the soil, being B. vulgaris (beet) the most sensitive. Thus, due to its ease of cultivation, high sensitivity, and fast initial growth, beet can be used as an indicator species of tembotrione presence in the soil solution. The sorption of this herbicide was higher in the Histosol and it is directly related to the organic matter content. RESUMO: Estudos sobre o comportamento de herbicidas no solo podem ser realizados utilizando métodos biológicos e químicos. A condição para o método biológico ser eficiente depende da sensibilidade da espécie indicadora às baixas concentrações do herbicida na solução do solo. Entre os herbicidas comumente usados no Brasil para a cultura do milho, destaca-se o tembotrione; nas últimas safras, tem-se relatado intoxicação de algumas culturas quando cultivadas em sucessão a esta cultura. Esse fato pode ser atribuído a recomendações do tembotrione sem o conhecimento de suas interações com os coloides dos solos tropicais. Nesta pesquisa, selecionou-se uma espécie vegetal indicadora de resíduos do tembotrione no solo, após a triagem de 12 espécies. Estimou-se em seguida a sorção desse herbicida em Latossolo Amarelo, Organossolo e Latossolo Vermelho-Amarelo com diferentes atributos. Inicialmente, após a triagem das 12 espécies vegetais, selecionaram-se as duas mais eficientes em detectar o tembotrione no solo. Na segunda etapa, foi selecionada a espécie mais sensível. Na terceira, foi avaliada a sorção do tembotrione nos três solos utilizando a espécie selecionada. Das 12 espécies avaliadas, Beta vulgaris e Brassica oleracea var. capitata foram as mais eficientes em detectar o tembotrione em baixas concentrações no solo, sendo B. vulgaris (beterraba) a mais sensível. Conclui-se que a beterraba, pela sua facilidade de cultivo, alta sensibilidade e rápido crescimento inicial, pode ser usada como espécie indicadora da presença do tembotrione na solução do solo. A sorção desse herbicida foi maior no Organossolo e está diretamente relacionada ao teor de matéria orgânica.

The cultivation of transgenic soybean plants using the glyphosate resistant gene (RR soybeans), takes up about 47% of the world’s cropping area. Despite the large area planted with soybeans resistant to glyphosate, there are very few studies of the environmental impact of this technology, especially in tropical areas. Thus, this study aimed to evaluate the impact of the cultive of RR soybeans and the use of glyphosate on the community of soil surface arthropods. The experiment was conducted in Coimbra, Minas Gerais state for two agricultural years. The experimental design was conducted in randomized blocks with five replications. The treatments were: non-transgenic soybean with mechanical weeding; RR soybean with mechanical weeding; RR soybean with one application of glyphosate and RR soybean with three applications of glyphosate. The populations of the soil surface arthropods were sampled over two years of cultivation (2007/2008 and 2008/2009). The cultive of RR soybean did not affect the richness and abundance of arthropods. A lower number of predators and detritivorous arthropods were observed in the treatments with one or three applications of glyphosate. Lower densities of arthropods were observed on the cultive of transgenic soybeans with three applications of glyphosate compared to the other treatments, especially the predators Achaearaneasp. (Araneae: Theridiidae), Oxypodinisp. (Coleoptera: Staphylinidae), Solenopsisspp. (Hymenoptera: Formicidae), the detritivorous Entomobryidae (Collembola), Hypogastrurasp. (Collembola: Hypogastruridae) and Xyleborussp. (Coleoptera: Scolytidae). The results indicate that the insertion of the glyphosate resistant gene does not affect the richness and abundance of the arthropods, however the use of glyphosate reduce the densities of predators and detritivorous on the soil surface. RESUMO: O cultivo de plantas transgênicas de soja com genes de resistência ao glyphosate (soja RR) ocupa cerca de 47% da área mundial com essa cultura. Apesar da grande área cultivada com soja resistente ao glyphosate, são escassos os estudos sobre o impacto ambiental dessa tecnologia, principalmente em áreas tropicais. Assim, o objetivo deste estudo foi avaliar o impacto da soja RR e do glyphosate sobre a comunidade de artrópodes da superfície do solo. O experimento foi realizado no município de Coimbra, Estado de Minas Gerais, durante dois anos agrícolas. O delineamento experimental foi em blocos casualizados com cinco repetições. Os tratamentos estudados foram: soja não transgênica com capina mecânica das plantas daninhas; soja RR com capina mecânica das plantas daninhas; soja RR com uma aplicação de glyphosate; e soja RR com três aplicações de glyphosate. As populações de artrópodes da superfície do solo foram amostradas em dois cultivos: o primeiro no biênio 2007/2008 e o segundo no biênio 2008/2009. A soja transgênica RR não afetou a riqueza e a abundância dos artrópodes. Menores riquezas de artrópodes predadores e detritívoros foram observadas nos tratamentos que receberam uma ou três aplicações de glyphosate. Foram observadas menores densidades de artrópodes na soja transgênica com três aplicações de glyphosate do que nos demais tratamentos, sobretudo dos predadores Achaearaneasp. (Araneae: Theridiidae), Oxypodinisp. (Coleoptera: Staphylinidae) e Solenopsissp. (Hymenoptera: Formicidae) e dos detritívoros Entomobryidae (Collembola), Hypogastrurasp. (Collembola: Hypogastruridae) e Xyleborussp. (Coleoptera: Scolytidae). Os resultados indicam que a inserção do gene de resistência ao glyphosate não afeta a riqueza e abundância dos artrópodes e que o uso de três aplicações do herbicida reduz as densidades de predadores e detritívoros da superfície do solo.

O tebuthiuron é um dos herbicidas mais utilizados na cultura da cana-de-açúcar e tem como característica a longa persistência no solo. Quando utilizado sem o conhecimento de suas interações com os atributos dos solos, pode reduzir a sustentabilidade dos sistemas de cultivos e contaminar águas superficiais e subterrâneas. Nesta pesquisa, utilizando a Cromatografia Líquida de Alta Eficiência, foram avaliados os efeitos da adição de matéria orgânica em um Latossolo Vermelho-Amarelo sobre a sorção e dessorção do tebuthiuron. Conclui-se que existe relação direta entre a sorção do tebuthiuron e os teores de matéria orgânica no Latossolo Vermelho-Amarelo e relação inversa para a dessorção. O índice de histerese foi menor nas amostras com alto conteúdo de matéria orgânica. Tebuthiuron is one of the most widely used herbicides in the sugarcane culture and its characteristic is the long persistence in soil. When used without knowing its interactions with soil attributes, it can reduce the sustainability of cropping systems and contaminate surface and groundwaters. In this research, by using a high-performance liquid chromatography, the effects of adding organic matter in a Red-Yellow Latosol were evaluated, as for the sorption and desorption of tebuthiuron. It was concluded that there is a direct relation between the sorption of tebuthiuron and the organic matter content in Red-Yellow Latosols and there is an inverse relation for desorption. The hysteresis index was lower in samples with high organic matter content.

In many plant species, tolerance to toxic metals is highly dependent on glutathione, an essential metabolite for cellular detoxifi cation. We evaluated the responses of glutathione metabolism to arsenite (As III ) in Salvinia molesta , an aquatic fern that has unexplored phytoremediation potential. Plants were exposed to diff erent As III concentrations in nutrient solution for 24 h. As III caused cell membrane damage to submerged leaves, indicating oxidative stress. Th ere was an increase in the glutathione content and ϒ-glutamylcysteine synthetase enzyme activity in the submerged and fl oating leaves. Th e glutathione peroxidase and glutathione sulfotransferase enzymes also showed increased activity in both plant parts, whereas glutathione reductase only showed increased activity in the submerged leaves. Th ese fi ndings suggest an important role for glutathione in the protection of S. molesta against the toxic eff ects of As III , with more eff ective tolerance responses in the fl oating leaves.

Weed control is one of the most relevant costs of sugarcane production. If weeds are not controlled at the right time, the productivity and longevity of sugarcane plantations are reduced. In this crop, chemical control is the most used method, since it is efficient and it has a lower cost. Differentiated tolerance of sugarcane cultivars to the herbicide clomazone has been observed in the fields. However, there is no scientific evidence of this effect on the productivity of crops. This study evaluated the effects of clomazone on three sugarcane cultivars (RB966928, RB93579 and RB867515). Herbicide application was performed 40 days after the emergence of sugarcane plants and 7, 14, 21 and 28 days after the application, the toxicity caused by the herbicide in the culture was evaluated through grades ranging from 0 (no toxicity) to 100 (plant death). The harvest was performed 580 days after the herbicide application. On this occasion, the length and diameter of the stem, number of tillers, tons of stems per hectare, total soluble solids of the juice, sucrose of the juice, apparent purity of the juice, sugarcane fiber, reducing sugars and total recoverable sugars were evaluated. The differential tolerance among sugarcane cultivars in response to clomazone application in the early stages of crop development was confirmed. Nevertheless, in all cultivars, the symptoms of intoxication disappeared over time and did not reflect on crop productivity. It was concluded that plant control in the sugarcane crop with clomazone, following the recommendation of the manufacturer, does not interfere negatively in the growth, development and productivity of the crop. RESUMO As plantas daninhas, se não controladas no momento adequado, reduzem a produtividade e longevidade dos canaviais. Nesta cultura, o método químico de controle das plantas daninhas, por ser eficiente e de menor custo, é o mais utilizado. No campo, tem-se observado tolerância diferenciada de cultivares de cana-de-açúcar ao herbicida clomazone. Contudo, não existe comprovação científica desse efeito sobre a produtividade dos cultivares. Neste trabalho foram avaliados os efeitos do clomazone em três cultivares de cana-de-açúcar (RB966928, RB93579 e RB867515). A aplicação do herbicida foi feita aos 40 dias após emergência das plantas de cana, e aos 7, 14, 21 e 28 dias após a aplicação foram avaliadas as intoxicações causadas pelo herbicida na cultura, atribuindo-se notas que variaram de 0 (ausência de intoxicação) até 100 (morte das plantas). Aos 580 dias após a aplicação foi realizada a colheita da cultura. Nessa ocasião, foram avaliados o comprimento e diâmetro do colmo, número de perfilho, tonelada de colmos por hectare, sólidos solúveis totais do caldo, sacarose do caldo, pureza aparente do caldo, fibra da cana, açúcares redutores e açúcares totais recuperáveis. Foi confirmada a tolerância diferenciada entre cultivares de cana-de-açúcar à aplicação do clomazone no início de desenvolvimento da cultura. Entretanto, os sintomas de intoxicação desapareceram ao longo do tempo e não refletiram na produtividade da cultura. Concluiu-se que o controle de plantas na cultura da cana-de-açúcar com o clomazone, seguindo a recomendação do fabricante, não interfere no crescimento, no desenvolvimento e na produtividade da cultura.