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Roots play a fundamental role in forest ecosystems, but obtaining samples from deep layers remains a challenging process due to the methodological and financial efforts required. In our quest to understand the dynamics of Eucalyptus roots, we raise three fundamental questions. First, we inquire about the average extent of the roots of two contrasting Eucalyptus genotypes. Next, we explore the factors that directly influence the growth and depth of these roots, addressing elements such as soil type, climate, and water availability. Lastly, we investigate how the variation in Eucalyptus species may impact root growth patterns, biomass, and carbon stock. In this study, we observed that the maximum root depth increased by an average of 20% when genotypes were grown on sites with higher water availability (wet site). E. urophylla stands had a higher biomass and carbon stock (5.7 Mg C ha-1) of fine roots when cultivated on dry sites (annual rainfall~727 mm) than the wet sites (annual rainfall~1590 mm). In E. grandis × E. camaldulensis stands, no significant differences were observed in the stock of fine root biomass (3.2 Mg C ha-1) between the studied environments. Our results demonstrated that genotypes with greater drought tolerance (E. grandis × E. camaldulensis) tend to maintain higher stocks of fine root biomass (3.2-6.3 Mg ha-1) compared to those classified as plastic (E. urophylla), regardless of the edaphoclimatic conditions of the cultivation site. Finally, our research helps understand how Eucalyptus trees adapt to their environment, aiding sustainable forest management and climate change mitigation. We also provide a practical tool to estimate underground biomass, assisting forest managers and policymakers in ensuring long-term forest sustainability.

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The adaptive nature of the galler habit has been tentatively explained by the nutrition, microenvironment, and enemy hypotheses. Soil attributes have direct relationships with these three hypotheses at the cellular and macroecological scales, but their influence has been restricted previously to effects on the nutritional status of the host plant on gall richness and abundance. Herein, we discuss the ionome patterns within gall tissues and their significance for gall development, physiology, structure, and for the nutrition of the gallers. Previous ecological and chemical quantification focused extensively on nitrogen and carbon contents, evoking the carbon-nutrient defence hypothesis as an explanation for establishing the plant-gall interaction. Different elements are involved in cell wall composition dynamics, antioxidant activity, and regulation of plant-gall water dynamics. An overview of the different soil-plant-gall relationships highlights the complexity of the nutritional requirements of gallers, which are strongly influenced by environmental soil traits. Soil and plant chemical profiles interact to determine the outcome of plant-herbivore interactions and need to be addressed by considering not only the soil features and galler nutrition but also the host plant's physiological traits. The quantitative and qualitative results for iron metabolism in gall tissues, as well as the roles of iron as an essential element in the physiology and reproduction of gallers suggest that it may represent a key nutritional resource, aligning with the nutrition hypothesis, and providing an integrative explanation for higher gall diversity in iron-rich soils.

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The low availability of phosphorus and water in soil can promote the remobilization of carbohydrates in the plant, releasing energy to mitigate stress. In this context, our objective was to analyze the production and allocation of carbohydrates in plants of Carapa guianensis Aubl. submitted to different doses of phosphate fertilization, during the rainy and dry seasons, in the western region of Pará. We used three phosphorus dosages (0, 50, 250 kg ha−1) as treatments. We evaluated the plants during the dry and wet seasons. We quantified dry matter production, phosphorus content, total soluble sugars, reducing sugars, sucrose, and starch. Phosphate fertilization and different evaluation periods influenced carbohydrate concentrations (p < 0.05) in plants. The highest levels of P in the leaves were registered in October and, in the roots the content decreased with the passage of time in all treatments. The control had higher dry matter production in leaves and stems. During the dry season, there was an accumulation of carbohydrates in plants and a low production of dry matter. Soluble sugars and sucrose tended to be allocated to the stem, reducing sugars to the leaves and starch to the roots, in most periods. In general, C. guianensis seedlings were not very responsive to phosphorus addition.

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Despite the widespread occurrence of fungal endophytes (FE) in plants inhabiting arid ecosystems, the environmental and soil factors that modulate changes in FE diversity and community composition along an aridity gradient have been little explored. We studied three locations along the coast of the Atacama Desert in Chile, in which the plant Aristolochia chilensis naturally grows, and that differ in their aridity gradient from hyper-arid to semi-arid. We evaluated if root-associated FE diversity (frequency, richness and diversity indexes) and community composition vary as a function of aridity. Additionally, we assessed whether edaphic factors co-varying with aridity (soil water potential, soil moisture, pH and nutrients) may structure FE communities. We expected that FE diversity would gradually increase towards the aridity gradient declines, and that those locations that had the most contrasting environments would show more dissimilar FE communities. We found that richness indexes were inversely related to aridity, although this pattern was only partially observed for FE frequency and diversity. FE community composition was dissimilar among contrasting locations, and soil water availability significantly influenced FE community composition across the gradient. The results indicate that FE diversity and community composition associated with A. chilensis relate to differences in the aridity level across the gradient. Overall, our findings reveal the importance of climate-related factors in shaping changes in diversity, structure and distribution of FE in desert ecosystems.

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In a typical year in the central Amazon, there is a mild dry season, but its effect on stem growth of multipurpose forest tree species is not yet well known. This study aimed to determine the individual effect of microclimatic parameters on stem growth after removing the influence of intercorrelation among microclimatic variables. Monthly stem diameter increment was measured in six species (46 trees) from January 2018 to December 2020. Microclimatic variables recorded were irradiance, air temperature, rainfall, and vapor pressure deficit. Principal component regression was used to assess the effect of micrometeorological variability on stem growth. On average, stem growth increased with an increase in rainfall and soil water content, but decreased with rise in maximum temperature and maximum vapor pressure deficit. These findings indicate that, when removing the effect of intercorrelation between microclimatic parameters, vapor pressure deficit may, in fact, affect stem growth. We demonstrate that the reduction in stem growth during the dry season can also be related to an increase in maximum temperature and maximum vapor pressure deficit, and not only to a decline in soil water content.(AU)

Em um ano típico na Amazônia central, há uma estação seca amena, mas seu efeito sobre o crescimento do tronco de espécies de uso múltiplo ainda é pouco conhecido. Este estudo teve como objetivo determinar o efeito individual de variáveis microclimáticas sobre crescimento do tronco após remover a influência da intercorrelação entre os fatores climáticos. O incremento mensal do diâmetro do tronco foi medido em seis espécies (46 árvores) de janeiro de 2018 a dezembro de 2020. As variáveis microclimáticas medidas foram irradiância, temperatura do ar, precipitação pluvial e déficit de pressão de vapor. Utilizou-se regressão de componentes principais para avaliar o efeito da variabilidade micrometeorológica sobre crescimento do tronco. Em média, o crescimento do tronco aumentou com o aumento da precipitação e do conteúdo de água do solo, mas diminuiu com o aumento da temperatura máxima e do déficit máximo de pressão de vapor. Estes resultados indicam que, removendo o efeito da intercorrelação entre os parâmetros climáticos, o déficit de pressão de vapor pode, de fato, ter um efeito sobre o crescimento do tronco. Demonstrou-se que a redução no crescimento do caule durante a estação seca também pode estar relacionada ao aumento da temperatura máxima e do déficit máximo de pressão de vapor, e não apenas ao declínio do teor de água no solo.(AU)

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Drought stress is an important concern worldwide which reduces crop yield and quality. To alleviate this problem, Trichoderma asperellum has been used as a plant growth-promoting fungus capable of inducing plant tolerance to biotic and abiotic stresses. Here, we examined the effect of T. asperellum inoculation on sugarcane plant above and belowground development under drought stress and investigated the role of this fungus on inducing tolerance to drought at physiological and biochemical levels. The experiment was performed in pots under greenhouse conditions, with four treatments and four replicates. The treatments consisted of sugarcane plants inoculated or not with T. asperellum and grown under drought stress and adequate water availability. Drought-stressed sugarcane plants inoculated with T. asperellum changed the crop nutrition and chlorophyll and carotenoid concentrations, resulting in increased photosynthesis rate, stomatal conductance, and water use efficiency compared to the non-inoculated plants. In addition, the antioxidant metabolism also changed, increasing the superoxide dismutase and peroxidase enzyme activities, as well as the proline concentration and sugar portioning. These cascade effects enhanced the root and stalk development, demonstrating that T. asperellum inoculation is an important tool in alleviating the negative effects of drought stress in sugarcane. Future studies should be performed to elucidate if T. asperellum should be reapplied to the sugarcane ratoons.

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RESUMO A mineração expõe à superfície material genericamente denominado de substrato, que possui atributos físicos, químicos e biológicos diferentes do solo natural. O lodo de estações de tratamento de esgoto (ETE) é a principal fonte de matéria orgânica utilizada na recuperação de áreas mineradas no Distrito Federal. Apesar de as tecnologias de recuperação afetarem positivamente o substrato minerado, seus efeitos sobre a disponibilidade de água para a vegetação foram pouco estudados. Diante disso, este estudo objetivou verificar se a disponibilidade de água em um substrato de mineração de cascalho foi alterada pela aplicação de lodo de ETE. Três materiais foram investigados: substrato minerado sem aplicação de lodo, substrato minerado com aplicação de lodo e solo sob Cerrado original. Esses materiais foram caracterizados por meio da granulometria, densidade aparente, porosidade total, microporosidade, macroporosidade, condutividade hidráulica saturada, teor volumétrico de água à capacidade de campo e ponto de murcha permanente. Posteriormente, monitorou-se, nesses materiais, o teor volumétrico de água e de ar durante 22 semanas. Os resultados indicaram que o substrato minerado armazenou água acima da capacidade de campo durante 86% do período investigado e o teor de ar permaneceu em níveis críticos durante 55% do mesmo período. A incorporação de lodo de ETE e a colonização de plantas aumentaram os valores de condutividade hidráulica na saturação (Ksat) e reduziu o período em que a água se manteve armazenada à capacidade de campo. Todavia, o regime de umidade do substrato tratado com lodo de ETE se manteve dissimilar ao do solo original usado como referência.

ABSTRACT Mining exposes to surface a material generically called substrate, which has different physical, chemical and biological attributes compared to natural soils. The wastewater sludge (WWS) is the main source of organic matter used in reclamation works of mines in the Federal District of Brazil. Reclamation works positively affect mine substrate but their effects on water availability (AW) have been little studied. This work aimed to evaluate the effects of WWS into a mine substrate on its hydraulic conductivity (Ksat) and AW. Samples of a mine substrate exposed to surface, the same material treated with wastewater sludge and soil under natural Savanna vegetation were collected and analyzed for bulk density, granulometry, total porosity, microporosity, macroporosity, saturated Ksat, volumetric water content at field capacity (FC) and at permanent wilt point (PWP). Subsequently, volumetric water and air content were monitored on the field for 22 weeks. Results showed that the substrate exposed by mining presented water content above FC during 86% of the investigation period and air content at critic levels during 55% of the same period. The incorporation of WWS and subsequent plant colonization increased Ksat values and shortened the period in which water was store at FC. However, the moisture regime in the substrate treaded with WWS remained dissimilar to that of the original soil used as reference.

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Climate change scenarios show that water availability could be decreasing in the near future, adding to the increasing problem of the growing water demands in socioeconomic sectors. The aim of this work was to generate a geographically explicit water balance concerning availability vs. demand in an overpopulated region of Mexico. Water balance and water deficit models were made for three periods of time: 1970-2000, and two future periods of time (2041-2060 and 2061-2080). Three global climate models were used in addition to two different climate scenarios from each (Representative Concentration Pathways (RCP) RCP 4.6 and RCP 8.5). Water demand for socioeconomic sectors was calculated through the water footprint. Water availability was 197,644.58 hm3/year, while that the water demand was 59,187 hm3/year. The socioeconomic sectors with the highest demand were domestic services (48%), agriculture (27%), livestock agriculture (20%), and timber production (5%). The highest water availability areas were not the same as those with the highest demand and vice versa. However, 39% of municipalities had a higher water demand than its availability. A significant reduction in water availability was identified, considering an interval of -15% to 40%. This variation depends on climate models, scenarios, and period of time. Areas with overpopulated cities in the region would have higher pressure on water availability. These results could be used in the implementation of public policies by focusing on adaptation strategies to reduce water deficit in the immediate future.

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BACKGROUND: The causes of geographic variation of body size in ectotherms have generally been attributed to environmental variables. Research in amphibians has favored mechanisms that involve water availability as an explanation for the geographic variation of body size. However, there are few studies at intraspecific level on amphibians that inhabit desert or semi-desert environments, where hydric restrictions are stronger. Here, we describe and inquire as to the causes of the geographic variation of body size in the semi-desert toad Rhinella atacamensis, a terrestrial anuran that is distributed over 750 km along a latitudinal aridity gradient from the southern extreme of the Atacama Desert to the Mediterranean region of central Chile. We measured the snout-vent length of 315 adults from 11 representative localities of the entire distribution of the species. Then, using an information-theoretic approach, we evaluate whether the data support eight ecogeographic hypotheses proposed in literature. RESULTS: Rhinella atacamensis exhibits a gradual pattern of decrease in adult body size towards the north of its distribution, where the climate is more arid, which conforms to a Bergmann's cline. The best model showed that the data support the mean annual precipitation as predictor of body size, favoring the converse water availability hypothesis. CONCLUSIONS: Most studies in amphibians show that adult size increases in arid environments, but we found a converse pattern to expected according to the hydric constraints imposed by this type of environment. The evidence in R. atacamensis favors the converse water availability hypothesis, whose mechanism proposes that the foraging activity determined by the precipitation gradient has produced the clinal pattern of body size variation. The variation of this trait could also be affected by the decreasing productivity that exists towards the north of the species distribution. In addition, we found evidence that both pattern and mechanism are independent of sex. Lastly, we suggest that behavioral traits, such as nocturnal habits, might also play an important role determining this differential response to aridity. Therefore, the support for the converse water availability hypothesis found in this study shows that amphibians can respond in different ways to water restrictions imposed by arid environments.

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High Andean wetlands of the elevated plateaus of the Andes Mountains of Chile, Argentina, Perú and Bolivia are true oases that sustain life in this arid region. Despite their ecological value, they have been rarely studied and are vulnerable to climate change and human activities that require groundwater resources. One such activity that may be intensified in the near future is mining for nonmetallic minerals such as lithium, whose worldwide demand is expected to increase with the rise of electric vehicles that need batteries. To determine a baseline of the natural dynamics of these systems, which allows sustainable management, it is essential to understand the spatiotemporal dynamics of these wetlands. In this article, we studied the temporal and spatial dynamics of high Andean wetlands of Chile, with the aim of identifying the key processes that govern their dynamics. To do this, we used time series of Landsat data from 1984 to 2019 to study 10 high Andean wetlands. Furthermore, to characterize the climate variability in these systems, we studied the long-term relation between the changes in water and vegetation areas with rainfall and evaporation variability. It was found that the groundwater reservoir plays a key role in sustaining the high Andean wetlands. Wet years with a period of occurrence of 20-30 years are the years in which the groundwater reservoirs are actually recharged, and in between wet years, the groundwater reservoirs gradually release the water that sustains the aquatic ecosystems. Hence, groundwater exploitation should be carefully designed from a long-term perspective, as groundwater levels could take decades to recover.

RESUMO

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.

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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.(AU)

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Water is one of the natural resources most impacted by the development model adopted in Brazil. This is related to the widespread sense that water is abundant in the country, which makes it difficult to fully engage all levels of government. However, this sense of abundance also obscures the real problems of pollution, demand, availability and water resources conflicts. This study aims to strengthen water management and contribute to the evaluation of the processes of development in the northeast region of the state of Pará. This study uses Hydrographic Basin Sustainability Indices to consider the hydrological, environmental, social and water resources management situation of the Moju River Basin and to suggest a payment model for the use of its water resources. The results indicate that the existing framework of water use regulation is characterized by moderate sustainability and governance scores and a low degree of collection of fees for the use of water. In general, with the increase in the number of enterprises authorized to withdraw water from and release effluents into the river, there is a lack of information about water demand and availability. The water governance framework is characterized by poorly integrated environmental and water management common to most Amazonian municipalities. Thus, the Moju River Basin represents a pattern of unsatisfactory water resources management. This pattern highlights the importance of implementing existing water resources and environmental policies to reduce conflicts that involve land and water use.

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The growth and yield of sunflower plants can be influenced by the plant population arrangement and the type of irrigation system adopted to meet the water requirements of the crop. This study examines the influence of different irrigation systems and spacings between planting rows on the development of sunflower cultivars for the sub-middle region of São Francisco Valley. The experiment was laid out in a randomized block design with a split-plot arrangement in which the plots consisted of three irrigation systems (drip, micro-sprinkler and sprinkler); sub-plots were represented by three spacings between planting rows (0.65, 0.55 and 0.45 m); and sub-sub-plots corresponded to two sunflower cultivars (Hélio 251 and Hélio 360). The following variables were analyzed: plant height; number of leaves; stem diameter; number of heads; head diameter; dry biomass of stems, leaves and heads; and achene yield.The different irrigation systems and row spacings markedly influenced the growth of the sunflower cultivars. The highest yield of cultivar Hélio 251 was obtained with the drip irrigation system and 0.55 m spacing. Cultivar Hélio 360 achieved the highest yields when irrigated by the micro-sprinkler system at 0.55 and 0.45 m spacing. In the sprinkler irrigation system, cultivar Hélio 360 obtained the highest yield at 0.45 m spacing.

O crescimento e a produtividade de plantas de girassol podem ser influenciados pelo arranjo populacional de plantas e pelo tipo de sistema de irrigação adotado para suprir as necessidades hídricas da cultura. O objetivo com este trabalho foi avaliar a influência de diferentes sistemas de irrigação e espaçamentos entre linhas de plantio no desenvolvimento de cultivares de girassol, para a região do Submédio do Vale do São Francisco. O delineamento experimental foi em blocos casualizados dispostos em parcelas subsubdivididas, sendo as parcelas três sistemas de irrigação (gotejamento, microaspersão e aspersão), as subparcelas três espaçamentos entre linhas de plantio (0,65; 0,55; e 0,45 m) e as subsubparcelas duas cultivares de girassol (Hélio 251 e Hélio 360). As variáveis analisadas foram: altura de plantas, número de folhas, diâmetro do caule, número de capítulos, diâmetro do capítulo, biomassa seca do caule, folhas e capítulos e produtividade de aquênios. Os diferentes sistemas de irrigação e de espaçamento entrelinhas influenciaram o crescimento das cultivares de girassol de forma singular. A maior produtividade da cultivar Hélio 251 foi obtida quando submetida ao sistema de irrigação por gotejamento e ao espaçamento de 0,55 m. A cultivar Hélio 360 irrigado pelo sistema de microaspersão, alcançou as maiores produtividades, com os espaçamentos 0,55 m e 0,45 m. No sistema de irrigação por aspersão, a cultivar Hélio 360 expressou maior produtividade no espaçamento de 0,45 m.

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The growth and yield of sunflower plants can be influenced by the plant population arrangement and the type of irrigation system adopted to meet the water requirements of the crop. This study examines the influence of different irrigation systems and spacings between planting rows on the development of sunflower cultivars for the sub-middle region of São Francisco Valley. The experiment was laid out in a randomized block design with a split-plot arrangement in which the plots consisted of three irrigation systems (drip, micro-sprinkler and sprinkler); sub-plots were represented by three spacings between planting rows (0.65, 0.55 and 0.45 m); and sub-sub-plots corresponded to two sunflower cultivars (Hélio 251 and Hélio 360). The following variables were analyzed: plant height; number of leaves; stem diameter; number of heads; head diameter; dry biomass of stems, leaves and heads; and achene yield.The different irrigation systems and row spacings markedly influenced the growth of the sunflower cultivars. The highest yield of cultivar Hélio 251 was obtained with the drip irrigation system and 0.55 m spacing. Cultivar Hélio 360 achieved the highest yields when irrigated by the micro-sprinkler system at 0.55 and 0.45 m spacing. In the sprinkler irrigation system, cultivar Hélio 360 obtained the highest yield at 0.45 m spacing.(AU)

O crescimento e a produtividade de plantas de girassol podem ser influenciados pelo arranjo populacional de plantas e pelo tipo de sistema de irrigação adotado para suprir as necessidades hídricas da cultura. O objetivo com este trabalho foi avaliar a influência de diferentes sistemas de irrigação e espaçamentos entre linhas de plantio no desenvolvimento de cultivares de girassol, para a região do Submédio do Vale do São Francisco. O delineamento experimental foi em blocos casualizados dispostos em parcelas subsubdivididas, sendo as parcelas três sistemas de irrigação (gotejamento, microaspersão e aspersão), as subparcelas três espaçamentos entre linhas de plantio (0,65; 0,55; e 0,45 m) e as subsubparcelas duas cultivares de girassol (Hélio 251 e Hélio 360). As variáveis analisadas foram: altura de plantas, número de folhas, diâmetro do caule, número de capítulos, diâmetro do capítulo, biomassa seca do caule, folhas e capítulos e produtividade de aquênios. Os diferentes sistemas de irrigação e de espaçamento entrelinhas influenciaram o crescimento das cultivares de girassol de forma singular. A maior produtividade da cultivar Hélio 251 foi obtida quando submetida ao sistema de irrigação por gotejamento e ao espaçamento de 0,55 m. A cultivar Hélio 360 irrigado pelo sistema de microaspersão, alcançou as maiores produtividades, com os espaçamentos 0,55 m e 0,45 m. No sistema de irrigação por aspersão, a cultivar Hélio 360 expressou maior produtividade no espaçamento de 0,45 m.(AU)

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RESUMO A outorga de direito de uso da água é um dos principais instrumentos de gestão para controle quantitativo e qualitativo dos recursos hídricos. Para sua implantação, é necessário, entre outras ações, definir critérios e desenvolver ferramentas para análise integrada dos aspectos quantitativos e qualitativos da água. Dessa forma, o objetivo do estudo foi desenvolver um sistema para análise das outorgas de captação de água e diluição de efluentes aplicado à bacia hidrográfica do rio Piracicaba (MG). Inicialmente, foram realizados o levantamento e a preparação da base de dados geográfica, hidrológica e administrativa. O sistema foi desenvolvido utilizando tecnologias open source, sendo estruturado em três camadas: de dados, de negócios e de apresentação. De acordo com os resultados, constatou-se que os trechos mais críticos quanto à vazão passível de outorga localizam-se na foz e na cabeceira do rio Piracicaba. A análise dos dados permitiu concluir que o sistema determina, de forma consistente, a disponibilidade hídrica outorgável ao longo da hidrografia e as vazões de diluição e indisponível pelos lançamentos, além de identificar trechos dos cursos d'água com disponibilidade hídrica crítica, fornecendo subsídios para análises das outorgas quali-quantitativas dos recursos hídricos na bacia.

ABSTRACT The granting of water use rights is one of the main management instruments for the quantitative and qualitative control of water resources. For its implementation, it is necessary, among other actions, to develop tools for integrated analysis of the quantitative and qualitative aspects of water. Thus, the objective of the study was to create a system for the analysis of water abstraction and effluent dilution in the Piracicaba river basin in Minas Gerais. Initially, the survey and preparation of the geographic, hydrological and administrative database were carried out. The system was developed using open-source technologies, with a three-layer structure: data, business, and presentation. According to the results, it was verified that the most critical sections regarding the grantable flow available are located at the mouth and spring of the Piracicaba river. The analysis of the data allowed us to conclude that the system consistently determines the availability of water throughout the hydrography, the dilution flow and discharge unavailability, and identifies stretches of the watercourses with critical water availability, providing support for analyses of the quali-quantitative granting of water resources in the basin.

RESUMO

Freshwater has spatial and temporal constraints, affecting possibilities to generate electricity. Previous studies approached this from a water perspective quantifying water consumption of electricity to optimize water use, or from an electricity perspective using modeling methods to optimize electricity output. However, power plants consume different water volumes per unit of electricity, depending on the applied technology, and supply systems often include a mix of different technologies with a different water footprint (WF), an indicator of water consumption, per unit of electricity. When water availability varies in time, probably the contribution of different electricity generating technologies also varies in time, resulting in WF fluctuations. Focusing on electricity generation from the water perspective, we assessed how water availability affects an electricity mix's dynamics and its blue WF using Ecuador as a case study. We studied the Amazon and Pacific basins, which have different temporal and spatial water availability fluctuations, assessing monthly water availability, electricity production, and blue WFs per plant. The Amazon basin has smaller temporal and spatial availability fluctuations than the Pacific. The difference between the largest and smallest water availability in the Amazon basin is two-fold, in the Pacific four-fold. Hydropower generation in the Amazon basin contributes more than 60% to the electricity mix. However, hydropower is directly affected by water availability, and its production decreases in water-limited periods. For biomass plants, limited water availability affects the fuel source, sugarcane bagasse. As water availability decreases, other technologies in the mix take over, causing WF variation (from 4.8 to 8.6 103 m3 per month). Usually, less water-availability means more water-efficiency, implying fossil-fueled plants in the Pacific take over from hydropower in the Amazon. It is relevant to assess the water-electricity nexus in countries with electricity mixes dominated by hydropower because energy planning needs to consider water availability and electricity mix dynamics.

RESUMO

The objective of this study was to evaluate the space-time dynamics of the soil use and occupation of the Rio Roncador river basin between 1985 and 2010. The scenes were classified by two methods (partially unsupervised - K-Means and supervised - Maximum likelihood), the Thematic Mapper sensor products on the LANDSAT 5 orbital platform were used for both images of a 25-year time series (1985 to 2000). In order to measure the accuracy of the field the computer application Google Earth was used, in which nine classes (urban area, agricultural area, pasture, exposed soil, native forest, secondary vegetation, mangrove, altitude field and water) were collected. A multiple linear regression was performed, correlating the Normalized Difference Vegetation Index - mean NDVI (dependent variable) with the independent climatic variables (global solar radiation - MJm-2day-1, average air temperature - °C, relative humidity -%, evapotranspiration - mm d-1, and rain - mm). According to the general classification by Kappa parameter of the images for 2005 and 2010, they were identified as very good (68% and 74%). These results confirm that the Roncador River Basin is undergoing transformation in its landscape, with an average reduction of -49% in native vegetation areas due to the increase in urban areas (25%) and agriculture (31%). The statistical analysis showed that rainfall and air temperature were the only variables that presented significant sigma (0.04) and (0.02). The obtained coefficient of determination indicated that 47% of the variations of the "vegetation index" are explained by the environmental variables.

O objetivo deste estudo foi de analisar espaço-temporalmente a dinâmica do uso e ocupação do solo da bacia hidrográfica do Rio Roncador, localizada no município de Magé no Estado do Rio de Janeiro, entre os anos de 1985 a 2010. As cenas foram classificadas por dois métodos (parcialmente nãosupervisionada ­ K-Means e supervisionada ­ Máxima Verossimilhança), para ambos foram utilizados os produtos abordo da plataforma orbital LANDSAT 5 do sensor Thematic Mapper, para as imagens de uma sérietemporal de 25 anos (1985 a 2000). Para a aferição como verdade de campo utilizou-se se o aplicativo computacional Google Earth, no qual foram coletadas nove classes (área urbana, área agrícola, pastagem, solo exposto, floresta nativa, vegetação secundária, manguezal, campo de altitude e água). Foi feita uma regressão linear múltipla, correlacionando o Índice de Vegetação da Diferença Normalizada - NDVI médio (variável dependente) com as variáveis climáticas independentes (radiação solar global - MJm-2dia-1, temperatura média do ar - °C, umidade relativa do ar - %, evapotranspiração ­ mm d-1, e chuva - mm). Segundo a classificação geral pelo parâmetro Kappa das imagens para os anos de 2005 e 2010 estas foram identificadas como muito bom (68% e 74%). Estes resultados comprovam que a Bacia Hidrográfica do Rio Roncador está passando por transformação em sua paisagem, com redução média de (-49%) das áreas de vegetação nativa por aumento de áreas como urbana (25%) e agricultura (31%). A análise estatística evidenciou que a variável climática chuva e temperatura do ar foram às únicas que apresentaram sigma significativo (0.04) e (0.02), a regressão múltipla com R2 de 0.47, que significa que 47% das variações do "índice de vegetação" são explicados pelas variáveis ambientais.

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RESUMO

BACKGROUND: The importance of water to life is unquestionable. Most of the fresh water we use for daily activities comes from the aquifers, which in many cases due to misuse are overexploited and at risk. This article studies the aquifer that appeared in Laguna de Santiaguillo basin; it should be noted that the most important economic activity in the basin is agriculture. METHODS: By analyzing vector and demographic information, using GIS and with some field trips, the impact and risk on the level of disposition in every micro-basin that forms the basin were determined. RESULTS: The different modeling scenarios demonstrate that the basin and sub-basins that conform Santiaguillo are overexploited. DISCUSSION: The volumes concessioned are of such magnitude that they generate a condition of vulnerability to the activities of the basin and sustain the overexploitation conditions of the aquifer.

RESUMO

This study aimed to evaluate the growth and physiology of Annona squamosa seedlings under increasing irrigation depths and phosphorus doses. The experiment was conducted in protected environment, evaluating five irrigation depths and four P2O5- doses, arranged in 5 x 4 factorial scheme, in randomized blocks, with four replicates and one plant per plot. Treatments were irrigation depths of 60, 80, 100, 120 and 140% of the real evapotranspiration of the seedlings ­ ETr and phosphorus doses of 0, 350, 700 and 1050 mg dm-3 of P2O5-. Plants were evaluated at 120 days after transplanting with respect to growth, gas exchanges, leaf water potential and total dry matter accumulation. Phosphorus dose of 350 mg dm-3 promotes satisfactory dry matter accumulation for A. squamosa seedlings, especially under 100% ETr irrigation. Leaf water potential and gas exchanges of A. squamosa are affected by water stress, through both lack and excess of water. Stomatal conductance is the variable most sensitive to the lack of water, whereas photosynthesis and water use efficiency are the most sensitive to the excess of water. Irrigation depth of 100% ETr is ideal to produce A. squamosa seedlings, but the irrigation depth of 80% ETr can be used to produce these seedlings, disregarding small losses of growth

Objetivou-se avaliar o crescimento e a fisiologia de mudas de A. squamosa sob lâminas crescentes de irrigação e doses de fósforo. O experimento foi conduzido em ambiente protegido, avaliando cinco lâminas de irrigação e quatro doses P2O5, arranjados em esquema fatorial 5 x 4, em blocos casualizados, com quatro repetições e uma planta por parcela. Os tratamentos das lâminas foram 60, 80, 100, 120 e 140% da evapotranspiração real das mudas ­ ETr e as quatro doses de fósforo 0, 350, 700 e 1050 mg dm-3 de P2O5. As plantas foram avaliadas aos 120 dias após o transplantio, quanto ao crescimento, trocas gasosas, potencial hídrico foliar e acúmulo de matéria seca total. A dose de fósforo de 350 mg dm-3 proporciona acúmulo de matéria seca satisfatório para as mudas de A. squamosa, principalmente sob irrigação com 100% da ETr. O potencial hídrico foliar e as trocas gasosas da A. squamosa são afetadas pelo estresse hídrico, tanto por falta como por excesso de água, sendo a condutância estomática a variável mais sensível a falta de água e a fotossíntese e eficiência do uso da água as mais sensíveis ao excesso de água. A lâmina de 100% da ETr é a ideal para a produção de mudas de A. squamosa, porém a lamina de 80% da ETr pode ser utilizada para a produção de mudas de A. squamosa, admitindo-se pequenas perdas no crescimento.

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