Abstract: Currently, Ecuadorian electrical system operation is experiencing several technical challenges, such as: 1) neighboring electrical systems integration in the Andean Electrical Interconnection System (SINEA) and 2) primary energy sources diversification. Under these new operating conditions, dynamic safety may be compromised by frequency stability issues. Based on frequency regulation, the objective is to use control mechanisms and available generation reserves to respond suitably to the electrical system's demands. Within this context, it becomes imperative to devise methodologies that ensures fast and accurate responses of power-frequency control equipment, such as speed regulators employed for Primary Frequency Regulation in generators. Given this foundation, an approach is presented relying on heuristic optimization methodologies, for the development of a tool that helps to compute the parametric identification and adjustment of speed controllers. Using measurements obtained from the proposed methodology, the developed tool was able to effectively perform the identification and validation of the speed regulation system of the CCS power plant as well as to propose new parameters that improve the response of the identified system.

Resumen: En la actualidad, la operación del sistema eléctrico ecuatoriano experimenta varios desafíos técnicos, tales como: 1) la integración de sistemas eléctricos vecinos en el Sistema de Interconexión Eléctrica Andina (SINEA) y 2) la diversificación de las fuentes primarias de energía. Bajo estas nuevas condiciones operativas, la seguridad dinámica puede ser afectada por problemas de estabilidad de frecuencia. Con base en la regulación de frecuencia se busca, a través de mecanismos de control y reservas de generación disponible, responder en forma adecuada a las exigencias del sistema eléctrico. Bajo este contexto, es necesario el desarrollo de metodologías que permitan la respuesta rápida y precisa de los equipos de control potencia - frecuencia, tales como los reguladores de velocidad, los cuales actúan de forma local en los generadores para realizar la Regulación Primaria de Frecuencia. Con estos antecedentes, se propone una metodología, basada en métodos heurísticos de optimización, para el desarrollo de una herramienta que permita realizar la identificación paramétrica y ajuste de los reguladores de velocidad. Con las mediciones obtenidas en base a la metodología propuesta, la herramienta desarrollada logró de manera efectiva realizar la identificación y validación del sistema de regulación de velocidad de la central CCS así como proponer nuevos parámetros que mejoran la respuesta del sistema identificado.

Capillary electromigration techniques can be understood as the ones used to separate neutral compounds, solvated ions and ionized species, considering the differentiated migration among them when an electrical field is applied within a capillary column filled with a background electrolyte. Several existing capillary electrophoresis setups provide the possibility of developing reliable quantitative assays of inorganic ions, organic acids, fatty acids, amino acids, carbohydrates, nucleic acids, proteins, hormones, vitamins, macromolecules, and more. Therefore, given the chemical complexity of bodily fluid matrices, capillary electrophoresis (CE) and its variations present themselves as an advantageous strategy for enhancing traditional clinical diagnostic methods and for the development of new ones. The recent advances in the study of the human metabolome associated with technological improvements towards medical applications make CE a very useful and versatile technique for clinical laboratory assays. Within this context, this review has the purpose of presenting some traditional methods used for exams of blood, urine, saliva, feces, and sweat, and how CE can be implemented as a real alternative to enable faster, automated, and cost-effective analysis with a comprehensive perspective that shall result in better diagnostic possibilities for patients, being a powerful tool for helping physicians on the precision medicine achievements. compounds species electrolyte acids carbohydrates proteins hormones vitamins macromolecules more Therefore matrices (CE context blood urine saliva feces sweat faster automated costeffective cost effective patients achievements

Resumen Introducción La pandemia de COVID-19 impactó negativamente la salud tanto física como mental a lo largo del mundo. Es importante identificar las manifestaciones psicológicas de la población y el impacto de la pandemia en los estilos de vida (actividad física, calidad del sueño). Objetivo Describir la relación entre el afecto (positivo y negativo) y la actividad física (AF) en estudiantes universitarios durante la pandemia de COVID-19. Método Se realizó una encuesta transversal a estudiantes de ciencias de la salud pertenecientes a tres instituciones de educación superior en México y Colombia. La AF se evaluó mediante la versión corta del Cuestionario Internacional de Actividad Física (IPAQ-S), y los afectos se midieron mediante el Índice PANAS. Se utilizó un modelo de regresión logística para evaluar la asociación entre AF y afectos. Resultados Se incluyeron 430 participantes entre 16 y 40 años. No encontramos diferencias entre hombres y mujeres en cuanto a edad, peso (IMC), nivel de AF ni el número de horas sentados por día, sin embargo, el consumo mensual de alcohol y tabaco fueron más frecuentes en hombres (p < .05) y las mujeres expresaron tener peor calidad de sueño (p < .05). Al ajustar por la cantidad de horas que pasaban sentados por día, el género, IMC, edad, calidad del sueño y los hábitos de consumo de tabaco y alcohol, los participantes expresaron tener más afectos positivos cuando realizaban mayor AF, sin embargo, no encontramos asociación entre AF y los afectos negativos. Discusión y conclusión Es fundamental priorizar la salud mental y las evaluaciones que determinan el impacto tardío de la pandemia de COVID-19 en el bienestar psicológico. Se considera necesario promover la AF en las comunidades universitarias para impactar positivamente en la salud mental de los estudiantes y brindar herramientas que faciliten el afrontamiento.

Abstract Introduction The COVID-19 pandemic has negatively impacted physical and mental health worldwide. It is essential to continue exploring the population’s psychological manifestations and the pandemic’s impact on lifestyles (physical activity, quality of sleep). Objective This research aimed to describe the relationship between affect (positive and negative) and physical activity (PA) in college students during the COVID-19 pandemic. Method A cross-sectional survey was conducted on health sciences students from three universities in Mexico and Colombia. PA was assessed using the short version of the International Physical Activity Questionnaire (IPAQ-S), and affects were measured using the PANAS index. A logistic regression model was used to assess the association between PA and affect. Results We included 430 participants between 16 and 40 years. We found no differences between the male and female participants regarding age, weight (BMI), PA, or the number of hours of sitting per day. The monthly consumption of alcohol and tobacco was more frequent in males (p < .05), and women expressed having worse sleep quality (p < .05). Adjusting for the number of hours spent sitting per day, gender, BMI, age, sleep quality, smoking and alcohol consumption habits, participants reported having more positive affect when they engaged in greater PA. No association was found between PA and negative affect. Discussion and conclusion Prioritizing mental health and assessments that determine the late impact of the COVID-19 pandemic on psychological well-being is critical. Promoting PA in university communities is considered a priority to positively impact students’ mental health and provide tools to facilitate coping.

Hot potassium carbonate (HPC) process aims to remove the CO2 present on synthesis gas. This removal is done in an absorption process, where takes place the reaction of CO2 with a K2CO3 solution. This reaction is slow and H3BO3 can be used to increase the rate of reaction. The rate-based model is the most suitable way to model the process. This approach uses different correlations to calculate important mass transfer and hydraulic parameters, such as: mass transfer coefficient, interfacial area, and liquid holdup. This paper aims to evaluate the performance of many correlations to represent the HPC process. An automatic procedure was developed to test a high number of equations, using MATLAB and Aspen Plus software. The best set of correlations was found after a comparison with industrial data. Correlations with errors less than 10% for the entire evaluated operating conditions were calculated for mass transfer coefficient and the interfacial area, as well as for liquid holdup.

Abstract Chelates are nutrient-rich compounds that enhance the condition of plant tissues as micronutrients. Micronutrient deficiencies particularly iron (Fe) and zinc (Zn) leads to various problems for plant including chlorosis and necrosis etc. An adequate intake of Fe and Zn etc. is required by the human body. Biofortification of cereals with Fe and Zn is seen as a cost-effective solution to the problem of Fe and Zn deficiencies as well. In recent decades, many chelating compounds have been established and incorporated into agricultural systems. The most recent formulation involves the use of amino acids synthesized with one or more nutrient ions to improve fertilizer efficiency and better respond to environmental conservation. In addition to its primary function as a source of micronutrients, aminochelled are an active nitrogen (N) stimulant in plant nutrition, preventing the negative effects of basic N fertilizers like urea. The use of amino chelates, rather than just chemical fertilizers, has been shown to provide better production and quality as well as higher nutritional concentrations in several experiments. Furthermore, this review sheds light on various aspects of amino chelates fertilizers including types, history, and their effects on agricultural crops. In spite of amino chelates fast dominance in many countries’ fertilizer countries, there is not enough scientific data and knowledge on the specific reactions of plants to biotic and abiotic stresses from amino fertilizers.

Resumo Os quelatos são compostos ricos em nutrientes que melhoram a condição dos tecidos vegetais como micronutrientes. Deficiências de micronutrientes, particularmente ferro (Fe) e zinco (Zn), levam a vários problemas para as plantas, incluindo clorose e necrose, etc. A ingestão de uma quantidade adequada de Fe e Zn, etc., é exigida pelo corpo humano. A biofortificação de cereais com Fe e Zn também é vista como uma solução econômica para o problema das deficiências de Fe e Zn. Nas últimas décadas, muitos compostos quelantes foram estabelecidos e incorporados em sistemas agrícolas. A formulação mais recente envolve o uso de aminoácidos sintetizados com um ou mais íons nutrientes para melhorar a eficiência do fertilizante e responder melhor à conservação ambiental. Além de sua função primária como fonte de micronutrientes, os aminoquelados são um estimulante de nitrogênio (N) ativo na nutrição das plantas, evitando os efeitos negativos de fertilizantes nitrogenados básicos como a ureia. O uso de aminoquelatos, ao invés de apenas fertilizantes químicos, tem mostrado proporcionar melhor produção e qualidade, bem como maiores concentrações nutricionais em vários experimentos. Além disso, a presente revisão lança luz sobre vários aspectos dos fertilizantes aminoquelatos, incluindo tipos, história e seus efeitos nas culturas agrícolas. Apesar do domínio rápido dos aminoquelatos em muitos países de fertilizantes, não há dados científicos suficientes e conhecimento sobre as reações específicas das plantas aos estresses bióticos e abióticos dos fertilizantes amino.

Abstract Bacteria responsible for causing infections are common in hospital environments, water, soil, and food products. The infection risk is intensified by the absence of public sanitation, poor quality of life, and food scarcity. These external factors promote the dissemination of pathogens by direct contamination or biofilm formation. In this work, we identified bacterial isolates obtained from intensive care units in the southern region of Tocantins, Brazil. We compared matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) techniques and 16S ribosomal ribonucleic acid (rRNA) molecular analysis; we also performed phenotypic characterization. Fifty-six isolates characterized using morphotinctorial tests were classified as gram-positive (80.4%; n = 45) and gram-negative (19.6%; n = 11) and were resistant to several antibiotic classes; notably, we identified the blaOXA-23 resistance gene in the ILH10 isolate. Microbial identification using MALDI-TOF MS resulted in the identification of Sphingomonas paucimobilis and Bacillus circulans. 16S rRNA sequencing revealed four isolates belonging to the genera Bacillus and Acinetobacter. The similarity was superior to 99% for Acinetobacter schindleri in the Basic Local Alignment Search Tool (BLAST), grouped in the clade superior to 90%. Several strains isolated from intensive care units (ICU) were resistant to various antibiotic classes. These techniques allowed for the identification of several microorganisms of importance in public health, enabling improvements in human infection control and proving the quality of inputs, food, and water.

Resumo As bactérias responsáveis por causar infecções são comuns em ambientes hospitalares, água, solo e produtos alimentícios. O risco de infecção é intensificado pela ausência de saneamento público, má qualidade de vida e escassez de alimentos. Esses fatores externos promovem a disseminação de patógenos por contaminação direta ou formação de biofilme. Neste trabalho, identificamos isolados bacterianos obtidos de unidades de terapia intensiva na região sul do Tocantins, Brasil. Comparamos técnicas de espectrometria de massa de tempo de voo com ionização por dessorção a laser assistida por matriz (MALDI-TOF MS) e análise molecular de ácido ribonucleico ribossômico 16S (rRNA); também realizamos caracterização fenotípica. Cinquenta e seis isolados caracterizados por testes morfotintoriais foram classificados como gram-positivos (80,3%; n = 45) e gram-negativos (19,6%; n = 11) e foram resistentes a várias classes de antibióticos; notavelmente, identificamos o gene de resistência blaOXA-23 no isolado de ILH10. A identificação microbiana usando MALDI-TOF MS resultou na identificação de Sphingomonas paucimobilis e Bacillus circulans. O sequenciamento do 16S rRNA revelou quatro isolados pertencentes aos gêneros Bacillus e Acinetobacter. A similaridade foi superior a 99% para Acinetobacter schindleri no BLAST, agrupado no clado superior a 90%. Várias cepas isoladas de ICU foram resistentes a várias classes de antibióticos. Essas técnicas permitiram a identificação de diversos microrganismos de importância em saúde pública, possibilitando melhorias no controle de infecções humanas e comprovando a qualidade dos insumos, alimentos e água.

ABSTRACT: The study aimed to describe the clinicopathological aspects of 37 cases of pythiosis, 34 in horses and three in mules, from properties located in the Amazon biome of Pará, Brazil. The clinical signs observed in the animals were weakness, poor-to-regular nutritional status, pale mucous membranes, itching at the lesion site, and lameness when the limbs were affected. The lesions were located on the lips, nostrils, rib region, thoracic and abdominal walls, scapular, distal limbs, foreskin, perineum and udder. Macroscopically, ulcerative and granulation-tissue-like masses were observed, with fistulous tracts filled with yellowish and foul-smelling serosanguinous discharges. In the biopsy, it was possible to visualize white and firm areas with foci of yellowish necrotic material and hardened masses, called kunkers. The histopathological examination showed a pyogranulomatous inflammatory reaction with the presence of Pythium insidiosum hyphae, which were impregnated with black, confirming the diagnosis of pythiosis in equids in the Amazon biome, being the first report of the disease in mules in the region.

RESUMO: O trabalho objetivou descrever os aspectos clínico-patológicos de 37 casos suspeitos de pitiose, 34 em equinos e três em muares, provenientes de propriedades localizadas no Pará, bioma amazônico brasileiro. Os sinais clínicos observados nos animais eram caracterizados por debilidade, estado nutricional de ruim a regular, mucosas pálidas, prurido no local da lesão, além de claudicação quando os membros foram acometidos. As lesões eram localizadas nos lábios, narinas, região das costelas, parede torácica e abdominal, escapular, distais dos membros, prepúcio, períneo e úbere. Macroscopicamente observavam-se extensas lesões ulceradas com intensa proliferação de tecido de granulação, de bordos irregulares, com tratos fistulosos, de consistência firme, denominados de “kunkers”, preenchidos com material amarelado e friável, possuindo exsudação serossanguinolenta de odor fétido. Ao exame histopatológico observou-se reação inflamatória piogranulomatosa com presença de hifas de Pythium insidiosum, as quais se impregnaram de negro, confirmando o diagnóstico de pitiose em equídeos no Bioma Amazônico, sendo o primeiro relato da doença em muares na região.

Abstract Water stress limits the initial growth and development of maize mass and grain, as well as the physiological process for absorbing the amount of mineral elements. The objective was to evaluate the effect of silicon on germination and growth of corn seedlings submitted to water deficit. The experiment was carried out in the laboratory and the experimental design was completely randomized (factorial 3 × 4), with three concentrations of calcium silicate (0.0; 1.0 and 2.0 mM) and 4 solutions of PEG-6000 to simulate different osmotic potentials (0, 0; -0.3; -0.6; -0.9 MPa). Germination percentage, germination speed index (GSI), mean germination time (MGT), percentage of non-germinated and abnormal germinated, length and dry matter of shoot, root and total seedlings were evaluated. Water deficiency reduced the parameters TG, GSI and MGT. The water deficit reduce the MSPA, MSR and MST with more than 80% reduction in mass from seedlings without deficiency to seedlings with deficiency. For CPA, CR and CT there was a reduction of at least 87%, 70% and 77%, respectively, among seeds without deficiency compared to seeds submitted to deficiency. The use of silicon in corn seeds did not attenuate the stress caused by water deficit simulated by PEG-6000.

Resumo O estresse hídrico limita o crescimento inicial e o desenvolvimento da massa e do grão de milho, assim como no processo fisiológico para a absorção da quantidade de elementos minerais. Objetivou-se avaliar o efeito do silício na germinação e no crescimento de plântulas de milho submetidas a deficiência hídrica. O experimento foi desenvolvido em laboratório e o delineamento experimental foi inteiramente casualizado (DIC) (fatorial 3 × 4), sendo três concentrações de Silicato de cálcio (0,0; 1,0 e 2,0 mM) e 4 soluções de PEG-6000 a simular diferentes potenciais osmóticos (0,0; -0,3; -0,6; -0,9 MPa). Foram avaliados a porcentagem de germinação, o índice de velocidade de germinação (IVG), o tempo médio de germinação (TMG), a porcentagem de não germinadas e de germinadas anormais, o comprimento e matéria seca da parte aérea, raiz e total das plântulas. A deficiência hídrica diminuiu os parâmetros TG, IVG e TMG. O déficit hídrico reduz a MSPA, MSR e MST com mais de 80% de redução da massa das plântulas sem deficiência para as plântulas com deficiência. Para CPA, CR e CT houve redução de, no mínimo, 87%, 70% e 77%, respectivamente entre as sementes sem deficiência em comparação as sementes submetidas a deficiência. A utilização de silício em sementes de milho não atenuou o estresse causado pela deficiência hídrica simulada por PEG-6000.

Abstract Uncaria tomentosa is a plant native to the Amazon that has immunomodulatory and antitumor properties due to the alkaloids found in the plant, being able to modify the immune response by potentiating or suspending the action of cytokines secreted by macrophages that induce the immune response, either by the classical route (M1) or through the alternative route (M2). Macrophages activated by M1 convert L-arginine into L-citrulline and nitric oxide (NO), whereas macrophages activated by the M2 pathway use the enzymatic activity of arginase to convert the same substrate into L-ornithine and urea. The aim of this work was to evaluate the immunostimulating activity of the crude hydroalcoholic extract from the bark of the U. tomentosa stem in RAW 264.7 macrophages. Concentrations of 0.2, 0.1 and 0.05 mg/mL of U. tomentosa extract associated with LPS, INF-γ and IL-4 inducers were tested by determining NO production and arginase enzyme activity. Nitric oxide production was enhanced by the extract when associated with LPS and LPS + INF-γ inducers. In the activity of the arginase enzyme, the extract decreased the stimulation of IL-4 on the enzyme, mainly at 0.2 mg/mL concentration. Therefore, it is concluded that the crude hydroalcoholic extract of the stem bark of U. tomentosa in RAW 264.7 cells, at a concentration of 0.2 mg/mL, showed considerable pro-inflammatory activity.

Resumo A Uncaria tomentosa é uma planta nativa da Amazônia que possui propriedades imunomoduladoras e antitumorais devido aos alcaloides encontrados no vegetal, sendo capaz de modificar a resposta imune ao potencializar ou suspender a ação de citocinas secretadas por macrófagos que induzem a resposta imune, seja pela via clássica (M1) ou pela via alternativa (M2). Macrófagos ativados pela M1 converte L-arginina em L-citrulina e óxido nítrico (NO), já os macrófagos ativados pela via M2 utilizam a atividade enzimática da arginase para converter o mesmo substrato em L-ornitina e ureia. O trabalho teve como objetivo avaliar a atividade imunoestimuladora do extrato hidroalcoólico bruto da casca do caule da U. tomentosa em macrófagos RAW 264.7. Foram testadas as concentrações 0.2, 0.1 e 0.05 mg/mL do extrato de U. tomentosa associadas aos indutores LPS, INF-γ e IL-4, por meio da determinação da produção de NO e atividade da enzima arginase. A produção de óxido nítrico foi potencializada pelo extrato quando associado aos indutores LPS e LPS + INF-γ. Na atividade da enzima arginase, o extrato diminuiu a estimulação da IL-4 sobre a enzima, principalmente na concentração 0.2 mg/mL. Portanto, conclui-se que o extrato hidroalcoólico bruto da casca do caule de U. tomentosa em células RAW 264.7, na concentração 0.2 mg/mL, demostrou atividade pró-inflamatória considerável.

Resumen: La materia orgánica del suelo (MOS) y su interacción con las partículas elementales del suelo (PES) determinan las tasas de mineralización, por lo que es necesario medir cuánto CO2 se libera por las fracciones elementales del suelo; sin embargo, con los métodos de fraccionamiento de las PES, se extrae una cantidad muy pequeña, lo que limita hacer ensayos de respiración con los métodos tradicionales, ya que requieren cantidades de 30 g para poder hacer mediciones en laboratorio. En este trabajo se hicieron pruebas para determinar si el equipo OxiTop es capaz de medir la respiración de muestras de suelo en cantidades pequeñas. Se colocaron cantidades de 10.0, 5.0, 1.0 y 0.5 g de muestras de mantillo (M), horizonte de fermentación (HF) y suelo (S) en frascos del equipo de 500 y 250 mL. Los resultados muestran que el equipo registra la cantidad de CO2 en todas las muestras, siendo mayores en el M que en las muestras de S. Además, el tamaño de frasco indicó que la respiración es proporcional al tamaño ya que en los frascos de 500 mL la cantidad de CO2 fue cercano al doble en comparación de los frascos de 250 mL en muestras de M y HF. En muestras de S los valores medidos en ambos frascos fueron muy similares. El equipo OxiTop es capaz de medir la emisión de CO2 en muestras pequeñas, pero el contenido de C de la muestra inf luyó, dado que, si los contenidos de C son bajos, la cantidad de CO2 será menor.

Summary: Soil organic matter (SOM) and its interaction with elementary soil particles (ESP) determine mineralization rates. Thus quantifying how much CO2 is released by soil elementary fractions is necessary. However, in the fractionation methods of ESP a very small amount is extracted limiting incubation tests with traditional methods, which require quantities of 30 g to make measurements in the laboratory. Tests were conducted to determine if the OxiTop equipment is capable of measuring the respiration of soil samples in small quantities of 10.0, 5.0, 1.0 and 0.5 g of litter samples (M), fermentation horizon (HF) and soil (S) in 500 and 250 mL equipment bottles. The results show that the equipment records the amount of CO2 in all the samples, which are greater in M than in S samples. In addition, the bottle size indicated that the respiration is proportional to size since in the 500 mL bottles the CO2 amount was nearly double compared to the 250 mL bottles in M and HF samples. In S samples the values measured in both bottles were very similar. The OxiTop equipment is able to measure CO2 emission in small samples. Nevertheless, the C content of the sample inf luenced the results, when the C contents are low the amount of CO2 is lower.

RESUMO A salinidade da água de irrigação ou do solo são fatores abióticos que mais impacta negativamente na produtividade das culturas, entre elas, o milho verde, sendo necessário encontrar alternativas para garantir a produção. Nesse contexto, objetivou-se avaliar as trocas gasosas, os pigmentos fotossintéticos e o crescimento do milho sob salinidade da água de irrigação e aplicação de peróxido de hidrogênio. O experimento foi conduzido no Centro de Ciências e Tecnologia Agroalimentar, Pombal, PB, pertencente à Universidade Federal de Campina Grande, no período de janeiro a fevereiro de 2015, utilizando-se do híbrido de milho ‘AG 1051’. Os tratamentos foram constituídos por dois níveis de salinidade da água de irrigação (0,3 e 2,0 dS m-1) e cinco concentrações de peróxido de hidrogênio (0, 40, 80, 160 e 320 µmol L-1) aplicadas via água de irrigação. O delineamento experimental foi o inteiramente casualizado, no esquema fatorial 2 × 5, com quatro repetições. A CEa de 2,0 dS m-1 reduz a transpiração, condutância estomática, clorofila total, carotenóides e crescimento inicial, mas não afeta o acúmulo de massa seca das plantas de milho. A aplicação de H2O2 via solo variando de 0 a 320 µmol L-1 promoveu redução na taxa de assimilação de CO2 e transpiração, bem como em concentrações de 0 a 160 µmol L-1 para condutância estomática de plantas irrigadas com CEa de 2,0 dS m-1. Aplicação de H2O2 via solo até a concentração de 320 µmol L-1 aumentou a altura de plantas, porém reduziu o diâmetro do colmo de milho.

ABSTRACT The salinity of irrigation water or soil is the abiotic factor that most negatively impacts the yield of crops, including green maize, so it is necessary to find alternatives to ensure production. In this context, this study aimed to evaluate gas exchange, photosynthetic pigments, and growth of maize under salinity of irrigation water and application of hydrogen peroxide. The experiment was conducted at the Center of Sciences and Agrifood Technology, Pombal, PB, belonging to the Federal University of Campina Grande, in the period from January to February 2015, using the maize hybrid ‘AG 1051’. The treatments consisted of two salinity levels of irrigation water (0.3 and 2.0 dS m-1) and five concentrations of hydrogen peroxide (0, 40, 80, 160, and 320 µmol L-1) applied via irrigation water. The experimental design was completely randomized, in a 2 × 5 factorial scheme, with four replicates. ECw of 2.0 dS m-1 reduces transpiration, stomatal conductance, total chlorophyll, carotenoids, and initial growth, but does not affect the dry mass accumulation of maize plants. Application of H2O2 via soil varying from 0 to 320 µmol L-1 causes reductions in the CO2 assimilation rate and transpiration, as well as at concentrations from 0 to 160 µmol L-1 for stomatal conductance of plants irrigated with ECw of 2.0 dS m-1. Application of H2O2 via soil up to a concentration of 320 µmol L-1 increases the plant height, but reduces culm diameter of maize.