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This article presents a discussion on the importance of digital tools that can be used in the process of teaching and learning additional languages at a time of emergency education. It is a bibliographic study with a qualitative approach, carried out with a search in different databases with criteria to select texts for analysis. Among the tools used, we highlight an analysis related to Duolingo, from a perspective of the CALL (Computer-Assisted Language Learning) approach, based on technical, theoretical, and social criteria. The results point to the potential of this tool due to the gratuity, multiplatform access, gamified interface, and activity management by the teacher through Duolingo Schools, in addition to the possibility of certifying the level of proficiency in the English language. The discussion also shows some limitations and social issues that highlight the precariousness of online education before and during the context of a global pandemic.

The freshwater prawn Macrobrachium equidens, which is native species of the Indo-Pacific Region, was recorded for the first time on the Amazon coast of Brazil. This species was found to inhabit the same environment as two native Macrobrachium species, M. amazonicum and M. acanthurus, and is morphologically very similar to the latter. The identification of the species was confirmed by the genetic analysis of sequences of the mitochondrial Cytochrome Oxidase (COI) gene. A detailed description of the morphological features and reproductive biology of M. equidens in this new environment is presented.O camarão de água doce Macrobrachium equidens, nativo da região do Indo-Pacífico, foi registrada pela primeira vez na costa da Amazônia Brasileira. Esta espécie foi encontrada habitando o mesmo ambiente que duas espécies nativas do gênero Macrobrachium: M. amazonicum e M. acanthurus, e é morfologicamente muito similar à última. A identificação dessa espécie foi confirmada pela análise da seqüência genética do gene mitocondrial Citocromo Oxidase (COI). Uma descrição detalhada das características morfológicas e biologia reprodutiva de M. equidens neste novo ambiente é apresentada.

The objective of this study was to evaluate the structural characteristics, yield and water use efficiency of forage cactus under daytime and nighttime irrigation in a Brazilian semiarid region. The experiment followed a completely randomized design in a 3 × 2 factorial scheme, with ten replications: three clones of forage cactus ("IPA Sertânia"—IPA, "Miúda"—MIU, "Orelha de Elefante Mexicana"—OEM) and two irrigation schedules (daytime and nighttime). Irrigation was applied once a week using a graduated cylinder. The structural characteristics (i.e., plant height and width, total number of cladode—TNC; cladode number per emergence order—CN1, CN2 and CN3; cladode area—CA; cladode area index—CAI), productive characteristics (fresh mass production per plant—FM and dry mass—DM) and water use efficiency (WUEFM and WUEDM) were obtained from the plant harvests. Our results showed that the irrigation schedules did not lead to significant differences in most of the response variables (p > 0.05), except for the TNC (13.2 und), CN2 (7.4 und) and CAI (1.58 m2 m−2) of MIU. It was observed that OEM presented the highest yield, WUEFM and WUEDM (p < 0.05). Adopting the OEM clone, regardless of the irrigation schedule, is the strategy that achieves the best production. [ABSTRACT FROM AUTHOR]

The objective of this study was to correlate the biophysical parameters of forage cactus with visible vegetation indices obtained by unmanned aerial vehicles (UAVs) and predict them with machine learning in different agricultural systems. Four experimental units were conducted. Units I and II had different plant spacings (0.10, 0.20, 0.30, 0.40, and 0.50 m) with East–West and North–South planting directions, respectively. Unit III had row spacings (1.00, 1.25, 1.50, and 1.75 m), and IV had cutting frequencies (6, 9, 12 + 6, and 18 months) with the clones "Orelha de Elefante Mexicana", "Miúda", and "IPA Sertânia". Plant height and width, cladode area index, fresh and dry matter yield (FM and DM), dry matter content, and fifteen vegetation indices of the visible range were analyzed. The RGBVI and ExGR indices stood out for presenting greater correlations with FM and DM. The prediction analysis using the Random Forest algorithm, highlighting DM, which presented a mean absolute error of 1.39, 0.99, and 1.72 Mg ha−1 in experimental units I and II, III, and IV, respectively. The results showed potential in the application of machine learning with RGB images for predictive analysis of the biophysical parameters of forage cactus. [ABSTRACT FROM AUTHOR]

The Aspidosperma pyrifolium Mart. & Zucc. is one of the main species of Caatinga biome, a seasonally dry tropical forest in Brazilian Semi-arid, very prominsing for the restoration of degraded or desertified areas. The combined effects of salt and water stress on morphological dynamics, biomass accumulation and gas exchange in A. pyrifolium were investigated. The experiment was conducted in state of Pernambuco, Brazil. A completely randomised design was adopted, where the plants were submitted to four water regimes based on a percentage of the reference evapotranspiration (ET0): 25%, 50%, 75% and 100%.ET0, and four salinity levels, using NaCl: 0.2 (control), 1.8, 2.82 and 3.93 dS m−1. Biometric, biomass and gas exchange data were obtained, and water use efficiency, momentary and intrinsic water use efficiency were calculated. The water deficit affected stem diameter, and stem and root biomass. Gas exchange showed a reduction for an increase in salt and water stress. Momentary and intrinsic efficiency were maximized under a water regime of 65%.ET0 and an electrical conductivity of 1.51 dS m−1, and 67%.ET0 and 1.75 dS m−1, respectively. It is concluded that the species A. pyrifolium changes the biomass partitioning between the plant structures to compensate the salt and water stress.

Os eventos climáticos extremos assumem grande relevância socioeconômica, principalmente nas regiões sensíveis climaticamente como as de clima Semiárido. A análise do regime pluviométrico de determinada região pode ser feita pelo Índice de Anomalia de Chuva (IAC), que permite classificar o regime pluviométrico quanto às anomalias anuais da precipitação, inferindo sobre os ciclos secos e úmidos. Diante disso, objetivou-se estudar a variabilidade espaço-temporal das precipitações de uma área inserida no Semiárido do Brasil. Para isso, utilizou-se o IAC para a normal climatológica 1987-2017 de 11 postos pluviométricos inseridos na mesorregião do Sertão do estado de Pernambuco. Foram analisadas as precipitações anuais e interanuais, determinadas as anomalias negativas e positivas ao longo da normal climatológica, e, por meio da interpolação espacial da precipitação pelo método do Inverso do Quadrado da Distância, elaborados mapas de distribuição espacial da pluviosidade em diferentes anomalias anuais. Os resultados apontaram que em 90,9% dos postos estudados a quadra chuvosa ocorre entre os meses de janeiro a abril, e que o acumulado destes meses corresponde a mais de 50% do volume anual precipitado, demonstrando assim, a irregularidade na distribuição anual da precipitação pluvial. Verificou-se que em 55% dos anos houve anomalias negativas na mesorregião do Sertão de Pernambuco. Outrossim, constatou-se, espacialmente, uma maior homogeneidade na distribuição espacial das anomalias negativas em relação às positivas, ou seja, os eventos de seca, quando ocorreram, tenderam a atingir toda a área estudada.

The proposal for a method of identifying the occurrence of desertification that has a strong association with in situ data leads to more assertive results when analysing the contribution of climate and social and economic factors to advancing the process. This study aimed to develop a methodology called the RisDes_Index to evaluate the evolution of the desertification process based on satellite data. The concept of the RisDes_Index method was based on the reflectance variables of the R, B and G bands, albedo and LAI of the Landsat 5/TM and Landsat 8/OLI satellites. Principal component analysis was used to assess the biophysical basis of the RisDes_Index by associating the results with micrometeorological data, physical and chemical properties, and vegetation cover data collected from five experimental sites in the semi-arid region of Brazil. These sites included one from a seasonally dry forest (i.e., the Caatinga), an agricultural cactus plantation, an area undergoing desertification, and two irrigated sugarcane crops (wetlands), one with and one without straw cover. The RisDes_Index was applied to all pixels of the images from 5 December 1991, 14 November 2001, 20 November 2009 and 6 October 2016 of an important desertification nucleus (DN) in the semi-arid region of Brazil, i.e., the DN of Cabrobó. The proposed RisDes_Index was able to identify areas with significant processes of desertification, which mainly occur in areas of sandy, acidic, bare soils with a high β value (Bowen ratio) and high soil temperature. The results of the RisDes_Index showed that in 5 December 1991, desertified areas comprised 38% of the total area of the DN of Cabrobó, expanding to 51% in 2016. Application of the RisDes_Index confirmed the advance of desertification in the DN of Cabrobó. This was due to a consequent increase in the water deficit and intensified deforestation to increase the areas of livestock farming. The RisDes_Index proved to be a robust method, as its estimation based on simple satellite products exhibited a strong association with biophysical variables of areas with different land uses and degradation levels. Thus, it is suggested that the RisDes_Index be applied in various regions of the world, with the idea of directing action to meet the advance of desertification. [ABSTRACT FROM AUTHOR]

Agricultural production in semi-arid regions is limited due to water availability. In addition, the water quality available for irrigation is often compromised due to the high salt content present. Millet is a forage species considered tolerant to water deficit and moderately salt tolerant. In view of the above, the objective was to evaluate the growth of millet under water and saline stress associates. The experiment was carried out in a randomized block design, in a 4x3 factorial scheme, composed of four levels of water replacement, based on crop evapotranspiration (ETc): 25%.ETc, 50%.ETc, 75%.ETc and 100%.ETc and three levels of water salinity (0.03, 2.0 and 4.0 dS m-1). With 25%.ETc independent of salinity, all morphological characteristics of millet were affected, occurring death of plants in the initial growth phase. In the absence of salt and greater availability of water, greater plant growth occurred. With respect to salinity, there was a reduction in the increment of all variables evaluated, with the highest reduction at the highest saline level (4.0 dS m-1). Water and salt stresses, when associated, reduce the growth of millet, since concentrations above 2.0 dS m-1 and less than 50%.ETc compromise its full development, providing declines in yield.

Abstract The vegetation structure is a good indicator of the conservation condition of an ecosystem, since it reflects alterations caused by anthropic action. This study proposes to analyze the phytosociological aspects of the Caatinga domain under anthropic disturbance and their correlations with hydrological variables. Twenty-five 400 m 2 plots were sampled in the municipality of Floresta - PE, Brazil. Phytosociological parameters such as density, frequency and dominance were calculated. The seasonality of plant area index was analyzed for six species. The association between structural characteristics and hydrological variables (throughfall, stemflow and interception loss) in the species was evaluated by multivariate analysis. A total of 930 individuals, six families and 10 species were recorded. The abundance of the species Cenostigma pyramidale in the area may be an indicator of the degree of change in the vegetation. The structural characteristics of the species revealed little association with rainfall partitioning.

Abstract This study investigated the water and radiation use efficiencies by Erythrina velutina and Enterolobium contortisiliquum under four water regimes. The experiment was carried out in the municipality of Serra Talhada, PE, Brazil. The experimental design was completely randomized with a 2 x 4 factorial arrangement and three replications. The water regimes were imposed from water replenishments based on the reference evapotranspiration (25, 50, 75 and 100% ET0). Water and radiation use efficiencies were calculated to the 120 days of growth. E. velutina showed a greater accumulated dry biomass (4.89 g pl-1) than E. contortisiliquum (2.22 g pl-1). The 75% ET0 water regime can be adopted without damage to the growth of both species. E. velutina was more efficient in the conversion of water (0.42 g l-1) and radiation in dry biomass (0.028 g MJ-1), indicating high environmental resilience, which is important features to choose species more adequate for reforestation activities.

In semi-arid regions, is necessary to explore strategies to mitigate abiotic stresses such as water deficit and salinity. This study aimed to evaluate the stress tolerance capacity of three species subjected to different water regimes and salinity levels, based on dry matter production and water use efficiency (WUE). The species Handroanthus impetiginosus, Vachellia farnesiana, and Amburana cearensis were evaluated in combination with different water regimes (50%, 75%, and 100% of reference evapotranspiration – ET0) and salinity levels (0.18, 1.50, and 1.90 dS m−1). The results show that biomass accumulation increased at 50% and 75% ET0, while the WUE decreased at 100% ET0. The salinity level (1.90 dS m−1) caused reductions in leaf dry biomass (LDB), total dry biomass (TDB), LDB/TDB ratio, and WUE. The negative effects of high salinity on plant height were greater with the application of 75% ET0. The highest WUE was obtained at 50% ET0 for A. cearensis and H. impetiginosus, while V. farnesiana obtained the highest WUE at 75% ET0. A. cearensis exhibited the highest biomass accumulation (2.58 g) and WUE (0.21 g L−1). Overall, the species can tolerate drought and salinity conditions, being sensitive to high salinity concentrations during their initial growth. The Caatinga is characterized by low water availability and soil salinization. Therefore, assessing the ability of native species to cope with these conditions allows for their utilization in reforestation programs in drought and salinity-exposed environments. Studies on the combined effects of these factors are scarce. The results indicated that native species show tolerance to drought and salinity conditions, albeit with some reductions in biomass production and water use efficiency at high NaCl concentrations. Among the species, A. cearensis performed the best under water and salinity stress conditions. [ABSTRACT FROM AUTHOR]