Semi-arid Northeast Brazil Research Articles

Everything's not lost: Caatinga areas under chronic disturbances still have well-preserved plant communities

The caatinga, a thorny deciduous shrub-arboreal vegetation predominant in the semiarid Northeast Brazil region, has faced chronic anthropogenic disturbance since the arrival of Europeans. Areas experiencing strong anthropogenic pressure and climatic vulnerability are often overlooked in floristic and phytosociological studies, leading to limited knowledge about their biological potential. Thus, our objective was to assess the current vegetation state in three severely degraded nuclei undergoing desertification in Ceará and determine, based on the analysis of plant diversity (richness) and structure, if there is potential for natural regeneration. We sampled 36 plots (3.24 ha), measuring trees and shrubs with a diameter at ground level (DGL) ≥ 3 cm. The vegetation was stratified into three degradation levels: open, intermediate, and closed. The open level, most impacted by human activities, exhibited reduced plant richness, density, biomass, and height compared to other levels. In contrast, the intermediate and closed covers, prevalent in the study area, showed no significant differences from each other or from caatinga areas outside the desertification nuclei. We concluded that even severely degraded areas should possess high biological potential due to the presence of preserved remnants serving as reservoirs to maintain diversity and vegetation structure in the region.

It's not all about drought: What “drought impacts” monitoring can reveal

Drought impacts monitoring has been called the missing piece in drought assessment. The potential to improve drought management is high but uncertain due to rare analyses of impacts datasets, predominantly because there are few impacts monitoring programmes to generate the datasets. Drought impacts monitoring is conducted on the ground in much of Brazil by local observers at monthly and municipality scale to support the Brazilian Drought Monitor. In Ceará state, within drought-prone semiarid northeast Brazil, over 3600 drought impacts reports were completed by agricultural extension officers from 2019 to 2022. We investigated, through manual coding and observer interviews, the reported drought impacts and impact drivers. Analysis provided a catalogue of the experienced impacts and showed that impacts still occur, and are often normalised, during non-drought periods, sometimes as lingering effects of previous droughts. The impact drivers were predominantly non-extreme hydrometeorological conditions or a result of socio-technical vulnerabilities such as insufficient water infrastructure. The normalisation of “impacts” included, in particular: a generally accepted high level of crop losses and consistently low reservoir levels around which the agricultural and domestic systems are adapted. Conventional drought indices often did not align with experienced impact severity, highlighting the limitations of relying solely on these indices for emergency response. Continual impacts monitoring could be extremely valuable anywhere in the world for identifying vulnerabilities and informing proactive measures to reduce drought and other hazard risk, in addition to guiding targeted mitigation efforts.

Perfil hematológico e bioquímica sérica de catetos (Pecari tajacu Linnaeus, 1758) no semiárido do nordeste brasileiro

ABSTRACT Hematological and biochemical analyses are paramount in assessing the health of different populations and their habitats, and knowledge on the specific values of each species is necessary, due to influence of several factors. In this context, this study aimed to determine the hematological and biochemical parameters of collared peccaries raised in captivity in the semi-arid Brazilian northeast associated to morphometric blood cell analyses. A total of 30 adult animals were investigated, divided into two groups (15 females and 15 males), averaging 20 kg and between 2 and 2.5 years old. Blood and serum samples were collected in the morning for hematological, serum biochemistry and cellular morphometry analyses. Data normality was determined by the Shapiro-Wilk test, and homoscedasticity, by Levene’s test. Concerning statistical differences between sexes, parametric data were analyzed by the t test for independent measurements and non-parametric data, by the Mann-Whitney test. Sex did not influence most of the studied variables, except for calcium, total proteins and urea and relative eosinophil counts. The environment and containment manner can influence collared peccary hematological and biochemical parameters, and blood cell morphometry and morphology data are similar to those of domestic cattle and carnivores.

Drought-impacted communities in social-ecological systems: Exploration of different system states in Northeast Brazil

This study applies ‘Social-Ecological Systems (SES)’ concepts with the aim of analysing why and how events happening across spatial, jurisdictional, and temporal scales influence droughts and their impacts in rural communities. To trace the evolution of droughts and their impacts on the livelihood system, we conducted a drought diagnosis in the rural community of Riacho da Cruz in the Banabuiú basin in the semi-arid Northeast of Brazil. We analysed how the livelihood of this community reacted differently to drought events and why the impacts of previous drought events either contributed to the adaptation of the livelihood system or its collapse. SES theory helped us posit that it is the collective capacity of stakeholders (nested across the levels of the different spatial, temporal and decisional scales of drought management) to manage their resilience to drought, that determines whether the considered system adapts, collapses or shifts into a new stable state, in response to drought. Monitoring these factors that influence drought resilience could enable the development of drought(-impact) indices that account for the spatial-temporal complexities of drought. Such results can aid in improving the targeting of policies toward drought-affected communities and ensuring they receive the necessary resources. Plain language summaryDrought and drought impacts are difficult to monitor. One reason is that they affect many different areas and groups of people. It is complicated to understand all the ways in which droughts can worsen or how they impact different groups, and why these effects can change over time and in different locations. This is what we investigate in this study using the Social-Ecological Systems (SES) theory. SES theory can help us understand how different parts of society and the environment interact and change over time. This theory can help us understand why certain events happen and how past events can still have an impact on current events. We applied SES theory to the drought-affected rural community of Riacho da Cruz in Northeast Brazil to understand why and how different drought events affected the community’s livelihood. Based on our findings, we developed a framework that can help identify some causes of drought impacts on the community’s livelihood. We believe that this framework can also be applied to identify and understand the causes of drought impacts in different sectors and locations. Building on the case of the community of Riacho da Cruz, we discuss how the SES theory can help monitor drought more accurately.

Physical, Nutritional, and Bioactive Properties of Mandacaru Cladode Flour (Cereus jamacaru DC.): An Unconventional Food Plant from the Semi-Arid Brazilian Northeast.

In this study, we evaluated the physical, nutritional, and bioactive properties of mandacaru cladode flour (Cereus jamacaru DC.). The granulometric profile revealed particles with non-uniform geometry, flakiness, a rectangular tendency, and a non-homogeneous surface, with particle sizes ranging from 20 to 60 µm. The flour presented low water activity (0.423), a moisture content of 8.24 g/100 g, high ash (2.82 g/100 g), protein (5.18 g/100 g), and total carbohydrate contents (74.48 g/100 g), and low lipid contents (1.88 g/100 g). Mandacaru flour is an excellent source of insoluble dietary fiber (48.08 g/100 g), calcium (76.33%), magnesium (15.21%), and potassium (5.94%). Notably, 1H NMR analysis revealed the presence of N-methyltyramine. Using HPLC chromatography, glucose was identified as the predominant sugar (1.33 g/100 g), followed by four organic acids, especially malic acid (9.41 g/100 g) and citric acid (3.96 g/100 g). Eighteen phenolic compounds were detected, with relevant amounts of kaempferol (99.40 mg/100 g), myricetin (72.30 mg/100 g), and resveratrol (17.84 mg/100 g). The total phenolic compounds and flavonoids were 1285.47 mg GAE/100 g and 15.19 mg CE/100 g, respectively. The mean in vitro antioxidant activity values were higher using the FRAP method (249.45 µmol Trolox TEAC/100 g) compared to the ABTS•+ method (0.39 µmol Trolox TEAC/g). Finally, the ascorbic acid had a content of 35.22 mg/100 g. The results demonstrate the value of mandacaru as a little-explored species and an excellent matrix for the development of flours presenting good nutritional value and bioactive constituents with excellent antioxidant potential.

The Vaza-Barris River: A late Quaternary decoupled accumulation-erosion model for rivers of the NE Brazil Atlantic passive margin

Limited insight is available regarding the links between the upstream-downstream fluvial response to climate changes and alluvial-coastal base-level factors in the passive Atlantic margin of tropical South America. This work attempts to characterize the last glacial-interglacial fluvial response of a typical semi-arid Brazilian Northeast River that drains Central-East Brazil's highlands. We integrate the full extension of the Vaza-Barris River alluvial plain record with the alluvial-coastal plain subsurface record. We used digital elevation models, satellite imagery, cores drill description, high-resolution seismic data, optical luminescence, and AMS 14C dating of alluvial terraces Five terrace levels, in the upstream provinces, and three terrace levels in the Coastal-alluvial province were identified. In the continental margin adjacent to the Vaza-Barris river-mouth, incised-valleys in the coastal shelf. Morphosedimentary proxies indicate that periods of aggradation and incision alternated during the late Quaternary due to different inland and eustatic dominant factors. We also estimate that the estuary stored a sediment fill of approximately ∼55 m since the late Pleistocene,. Thus, climate change and sea-level variations differentially controlled the fluvial response and the morphology of the adjacent continental margin along the fluvial system. The decoupled accumulation/erosion upstream-downstream patterns can be used as a model to be tested in fluvial systems of the passive margin of the Brazilian Northeast.

Response of vegetation to hydroclimate changes in northeast Brazil over the last 130 kyrs

In this paper, we use palynology and geochemical proxies to reconstruct late Quaternary vegetation changes within the hydrographic basin of Parnaíba, Northeast Brazil, over the last 130 kyrs. Findings are based on the analysis of a marine sediment core (GL-1248) retrieved from the western equatorial Atlantic (0°55.2′S, 43°24.1′W), close to the coast. Geochemical proxies (Fe/K ratio and ƐNd) indicative of soil erosion match changes in reconstructed vegetation, suggesting a dynamic pattern of hydrological disturbances and ecosystem evolution. Given that reconstructed vegetation does not present the same response to precipitation anomalies on the millennial scale, we sought the main drivers of vegetation changes in the Parnaíba watershed. Results indicate that vegetation succession was primarily influenced by austral insolation from March to May, which triggered changes in the pioneer vegetation types. Our study improves the knowledge of tropical vegetation dynamics in an orbital framework, suggesting 23-kyr precessional cycles as the main driver of landscape evolution in Northeast (NE) Brazil. We also infer that such past climate change events may have been a key causal factor of the high biodiversity of the Neotropics, mediated through the biological exchange of the Amazon and Atlantic rainforest species via ecological forest corridors in the semi-arid Northeast Brazil.

Reservoir sediment characterisation by diffuse reflectance spectroscopy in a semiarid region to support sediment reuse for soil fertilization

PurposeSoil erosion by water yields sediment to surface reservoirs, reducing their storage capacities, changing their geometry, and degrading water quality. Sediment reuse, i.e., fertilization of agricultural soils with the nutrient-enriched sediment from reservoirs, has been proposed as a recovery strategy. However, the sediment needs to meet certain criteria. In this study, we characterize sediments from the densely dammed semiarid Northeast Brazil by VNIR-SWIR spectroscopy and assess the effect of spectral resolution and spatial scale on the accuracy of N, P, K, C, electrical conductivity, and clay prediction models.MethodsSediment was collected in 10 empty reservoirs, and physical and chemical laboratory analyses as well as spectral measurements were performed. The spectra, initially measured at 1 nm spectral resolution, were resampled to 5 and 10 nm, and samples were analysed for both high and low spectral resolution at three spatial scales, namely (1) reservoir, (2) catchment, and (3) regional scale.ResultsPartial least square regressions performed from good to very good in the prediction of clay and electrical conductivity from reservoir (< 40 km2) to regional (82,500 km2) scales. Models for C and N performed satisfactorily at the reservoir scale, but degraded to unsatisfactory at the other scales. Models for P and K were more unstable and performed from unsatisfactorily to satisfactorily at all scales. Coarsening spectral resolution by up to 10 nm only slightly degrades the models’ performance, indicating the potential of characterizing sediment from spectral data captured at lower resolutions, such as by hyperspectral satellite sensors.ConclusionBy reducing the costly and time-consuming laboratory analyses, the method helps to promote the sediment reuse as a practice of soil and water conservation.

Minimum Rainfall Inter-Event Time to Separate Rainfall Events in a Low Latitude Semi-Arid Environment

Water scarcity in dry tropical regions is expected to intensify due to climate change. Characterization of rainfall events is needed for a better assessment of the associated hydrological processes, and the proposition of adaptation strategies. There is still no consensus on the most appropriate method to separate rainfall events from a continuous database, although the minimum inter-event time (MIET) is a commonly used criterion. Semi-arid regions of low latitudes hold a distinct rainfall pattern compared to their equivalent at higher latitudes; these seasonally dry tropical forests experience strong spatial–temporal variability with intense short-duration rainfall events, which, in association with high energy surplus and potential evaporation, leads to an atmospheric water deficit. In this study, we identified the most adequate MIET based on rainfall data continuously measured at 5-min intervals over the last decade (2009–2020) in the semi-arid northeast of Brazil. The rainfall events were grouped according to different MIETs: 15 min, 1 h, 2 h, 3 h, 6 h, 12 h, and 24 h to determine rainfall depth, duration and intensity at intervals of 5, 30, and 60 min, time between events, and respective temporal distribution, with and without single tip events. Including single tip events in the dataset affected the number of rainfall events and respective characteristics up to a MIET of 3 h. A MIET of 6 h is the most appropriate to characterize the rainfall distribution in this tropical semi-arid region. Three classes were defined based on rainfall depth, duration, and intensity: I-small events (77% below 40 mm and 32 mm/h), II-high intensity events (3% between 36 and 76 mm/h), III-longer events of higher depth (20%). This study is useful for understanding how the MIET relates to other ecohydrological processes and provides more precise information on the rainfall characteristics at the event scale.

Aeolian mobility in the Middle São Francisco Dune Field, Northeast Brazil, as a response to Caatinga's droughts and land-use changes

In the last decade, the semiarid northeast of Brazil (Caatinga biome) has experienced one of the most prolonged and most severe droughts ever recorded in regional history. The study of the landscape changes contributes to understanding the environmental, social, and economic consequences of extreme climate events in the region. Here, we investigate the marginal area of the Middle São Francisco dune field, where in recent years, aeolian landforms development and their migration have been observed. To map the migration line of the aeolian front, we used 2002–2019 high-resolution images, from which we estimate the migration rates and evaluate the monthly migration rates for several interannual intervals, particularly during the drought peaks. In the area of greatest migration, the dunes advanced 210 m in 18 years. In the first decade, under climatic conditions closer to the historical average, dunes migrated ~15 m/y, while in the second decade, they migrated 80 m at a rate of 9.4 m/y. Examining the ranges of intra-annual migrations, we estimate that the highest mobility rate was almost five times greater than the rate at the end of the decade. In addition, we calculated a dune mobility index and the dune's morphological patterns. We conclude that the morphodynamic processes of dune formation and migration were triggered mainly by vegetation removal from river banks. The more severe climatic conditions during the last drought (2012–2017) enabled the dunes to migrate relatively quickly. The last few years (2017–2019) were marked by a considerable reduction in aeolian mobility and stabilization of expansion margins, inducing the formation of barchan-parabolic dunes.

20-Years Cumulative Impact From Shrimp Farming on Mangroves of Northeast Brazil

Brazilian mangroves cover about 11,100 km2 and provide a wide range of ecosystem services. Despite their importance, they are one of the most impacted ecosystems because of combined influences of climate change, pollution, and direct conversion and loss. A major driver of environmental impacts is shrimp farming and this is particularly acute in the semi-arid northeast of Brazil, where mangroves are constrained in a narrow band along ephemeral estuaries that are often impacted by multi-year droughts. Recent changes to Brazilian law, in particular the Forest Code, have weakened protection for mangroves and associated “apicum” (salt pan) ecosystems. In NE Brazil, most shrimp ponds are converted from mangrove-adjacent “apicuns” rather than the mangroves themselves with periodic hydrological connectivity through dammed channels, allowing the flushing of effluents. As a result, the main impacts on mangroves are typically indirect, because of pollution inputs from shrimp pond effluents and associated loss of ecosystem services including reductions in primary productivity, carbon storage capacity, resilience to other environmental stressors, their efficiency as estuarine filters, and biodiversity and abundance of subsistence use of marine species. Soil damage and infrastructure remaining after shrimp pond deactivation impairs mangrove recovery. This extends the duration of the damage and allows the occupation of degraded areas by other activities that can permanently impair ecosystem function. In this review, we address several aspects of the shrimp culture boom in NE Brazilian, their features and consequences, and the future of mangroves in the region considering climate change and rising poverty. Our conclusions on the practices and outcomes of shrimp farming in mangroves are likely to apply to areas with similar environmental settings, e.g., semiarid regions worldwide, and particularly in the Latin America and Caribbean region, and our findings can be taken into account to improve conservation and management of these forests at the least to a regional scale.

Bacteria from tropical semiarid temporary ponds promote maize growth under hydric stress

World climate change has triggered soil water stress and imposed limitations on agricultural production. Plant growth-promoting bacteria (PGPBs) have been an efficient strategy to improve the biological supply and growth of plants under distinct abiotic stress conditions. We hypothesized that the soils from a temporary pond may harbor PGPBs with potential strains which increase maize tolerance to water deficit. We studied rhizosphere and bulk soil of Mimosa bimucronata in a temporary pond from semiarid Northeast Brazil to access strains with characteristics to promote plant growth and mitigate abiotic stress for maize crop. We isolated 355 bacterial isolates, from which 96 were selected based on the morphophysiological characterization to assess IAA production (42 % produced over 50 μg mL-1 of IAA), calcium phosphate solubilization (with one isolate achieving medium IS), biofilm and exopolysaccharides production (66 % and 98 % of isolates, respectively). Based on these mechanisms, the 30 most promising bacterial isolates were selected to assess biological nitrogen fixation (74 % of the isolates showed nitrogenase activity greater than 20 C2H4.h-1.mg-1), ACC deaminase activity (80 % of isolates) and growth in medium with reduced water activity (8 % of isolates grew in medium with water activity (Aw) of 0.844). We sequenced the 16S rRNA gene from the seven most promising isolates in in vitro and in vivo assays, which were identified as Staphylococcus edaphicus, Bacillus wiedmannii, Micrococcus yunnanensis, Streptomyces alboflavus, Streptomyces alboflavus, Bacillus wiedmanni and Bacillus cereus. In vivo, eleven isolates and three bacterial consortia did not differ from the control with nutrient solution, for total leaf area and root dry mass of maize. S. alboflavus (BS43) had the best in vivo results, not differing from the control with nutrient solution. We highlight the unpublished potential of Staphylococcus edaphicus and Streptomyces alboflavus in promoting the growth of plants under water stress. In addition, it is the first report of bacteria isolated from a temporary pond in the Brazilian semiarid which promoting plant growth attributes and development.

The role of ENSO flavours and TNA on recent droughts over Amazon forests and the Northeast Brazil region

AbstractAmazon tropical forests and the semiarid Northeast Brazil (NEB) region have registered very severe droughts during the last two decades, with a frequency that may have exceeded natural climate variability. Severe droughts impact the physiological response of Amazon forests, decreasing the availability to absorb atmospheric CO2, as well as biodiversity and increasing risk of fires. Droughts on this region also affect population by isolating them due to anomalous low river levels. Impacts of droughts over NEB region are related to water and energy security and subsistence agriculture. Most drought episodes over Amazonia and NEB are associated with El Niño (EN) events, anomalous warming over the Tropical North Atlantic (TNA), and even an overlapping among them. However, not all the dry episodes showed a large‐scale pattern linked to a canonical EN event or warm TNA episodes. For instance, dry episodes linked to EN events present distinct spatial patterns of precipitation anomalies depending on EN type (Central‐Pacific vs. Eastern‐Pacific EN), and NEB region experienced a severe drought in 2012 that is not attributed to EN or warm TNA events. Even in the case of the strong EN in 2015/16, some regional impacts have not been explained by EN contribution. This paper discusses the effects of CP and EP EN events, and the role of warm TNA events on tropical Walker and Hadley circulation leading to drought over Amazonia and NEB regions.

Genetic parameters and path analysis of traits of upland cotton for the brazilian semi-arid region

Upland cotton fiber is one of the most used natural fibers in the production of textile materials worldwide. For this reason, the selection of genotypes that meet the industry’s requirements is one of the main goals of cotton breeding programs. This study aimed to estimate the phenotypic and genotypic correlations among fiber traits and identify the direct and indirect effects of these traits on seed cotton yield of upland cotton genotypes in the semi-arid Brazilian Northeast. This study assessed 21 upland cotton genotypes from a complete diallel cross without reciprocals. The design was randomized blocks, with three replications and 21 treatments. The experiment was conducted in the municipality of Patos - PB, in 2015. The statistical analysis consisted of analysis of variance by the F test, phenotypic and genotypic correlation analysis, and path analysis. The studied materials revealed genetic variability for all traits. Path analysis has shown that the traits fiber elongation, fiber strength, and fiber fineness have a direct positive effect on seed cotton yield.

Variability of the Thermohaline Field in a Large Tropical, Well-Mixed Estuary: the Influence of an Extreme Draught Event

Todos os Santos Bay (BTS) is one of eleven large estuaries along the semi-arid Brazilian northeast coast. It is a positive, well-mixed estuary undergoing progressive fresh water limitations due to natural climatic processes and direct human intervention to the fluvial hydrology. This study investigates the variability of the thermohaline field along three water years (2013–2015) that encompassed close-to-normal hydric conditions and the most severe regional drought in the historical record. Moored temperature and conductivity sensors, monthly CTD profiling along the bay axis, and historical records of meteorology and river discharges showed that the seasonal oscillations of the thermohaline field are 2- to 3-fold larger than higher, tidal frequency oscillations, and that BTS becomes a seasonally negative, hypersaline estuary during a drought. Also, a density plug and inverse estuarine circulation can arise with a delay of the rainy season. Negative ecological impacts have been associated with such hydrographic conditions. Long-term climatic trends and future climatic projections indicate that the BTS and its catchment area may undergo more frequent and acute droughts, suggesting that the bay may often become a seasonally negative estuary.

Seasonal drought prediction for semiarid northeast Brazil: what is the added value of a process-based hydrological model?

Abstract. The semiarid northeast of Brazil is one of the most densely populated dryland regions in the world and recurrently affected by severe droughts. Thus, reliable seasonal forecasts of streamflow and reservoir storage are of high value for water managers. Such forecasts can be generated by applying either hydrological models representing underlying processes or statistical relationships exploiting correlations among meteorological and hydrological variables. This work evaluates and compares the performances of seasonal reservoir storage forecasts derived by a process-based hydrological model and a statistical approach. Driven by observations, both models achieve similar simulation accuracies. In a hindcast experiment, however, the accuracy of estimating regional reservoir storages was considerably lower using the process-based hydrological model, whereas the resolution and reliability of drought event predictions were similar by both approaches. Further investigations regarding the deficiencies of the process-based model revealed a significant influence of antecedent wetness conditions and a higher sensitivity of model prediction performance to rainfall forecast quality. Within the scope of this study, the statistical model proved to be the more straightforward approach for predictions of reservoir level and drought events at regionally and monthly aggregated scales. However, for forecasts at finer scales of space and time or for the investigation of underlying processes, the costly initialisation and application of a process-based model can be worthwhile. Furthermore, the application of innovative data products, such as remote sensing data, and operational model correction methods, like data assimilation, may allow for an enhanced exploitation of the advanced capabilities of process-based hydrological models.

Land uses, Nitrogen and Phosphorus estimated fluxes in a Brazilian semi-arid watershed

This paper presents the estimates of nitrogen and phosphorus loads associated with different land uses in a semi-arid watershed in the Brazilian northeast (NE). To calculate the annual loads and calibrate de estimates, we used emission factors related to natural processes and human activities from land uses and monitored the nutrient concentrations in surficial waters. The concentrations of TN were above the 2.18 mg N L−1 limit for lotic environments while the TP exceeded the limit value of 0.15 mg P L−1 established in the Brazilian legislation. The total loads LeN,P corresponded to 16,621 t N yr−1 and 3,211 t P yr−1 or 1,292 t N km−2 yr−1 and 250 t P km−2 yr−1. The anthropogenic emissions accounted for 82.1% of the N and 91.3% of the P emitted. The results for the Salgado river basin are lower than those estimated globally, but exceed the values obtained for the South American continent in an order of magnitude. The use of nutrient loads instead of concentrations, particularly in areas where detailed studies on nutrient concentrations are unavailable, such as in the semi-arid NE Brazil, may become a satisfactory approach to evaluate the sensitivity of aquatic systems to a further introduction of anthropogenic effluents.

Produtos de efeito fisiológico na produção de rosa de corte - aplicação e crescimento

The introduction of the cut rose culture in high temperature environment requires the use of technologies that allows its acclimation to the unusual environment. Products based on strobilurins, carboxamides and anilides as well as plant regulators that promote changes in the plant growth, can be a viable tool for the introduction of cut roses in the semiarid Northeast of Brazil. Thus, the objective of this study was to evaluate the effect of products with physiological effects on the growth of cut rose ‘Ambiance’ in the Submedium of the São Francisco Valley. The experimental design was a randomized block with four replicates and six treatments: control (water application); Boscalid; Pyraclostrobin; mixture of Boscalid + Pyraclostrobin; Fluxapyroxad + Pyraclostrobin; Kinetin + GA3 + IBA; and consisted of foliar applications every 15 days for 280 days. The growth evaluations were performed through physiological indexes assessment, chlorophyll content and production of flower buds per stem. The results obtained showed that, especially Boscalid, both isolated and combined with Pyraclostrobin, the Fluxapyroxad + Pyraclostrobin and the plant regulators provided better physiological responses on the growth of the rose ‘Ambiance’, considering the relative growth rate, net assimilation rate, leaf area ratio and specific leaf area. Although the average increase on production of flower buds per stem of all treatments applied in relation to the control was in the order of 135%, none of the treatments applied produced stem for cut roses with the required commercial standards, indicating that further studies are needed for an adequate introduction of the crop in Submedium of the São Francisco Valley.

Cotton Growth and Nutrient Uptake after Rock Phosphate, Gliricidia Prunings or Chemical Fertiliser Application in Soils of Semiarid Northeast Brazil

Cotton Growth and Nutrient Uptake after Rock Phosphate, Gliricidia Prunings or Chemical Fertiliser Application in Soils of Semiarid Northeast Brazil

Climatic characteristics of the 2010-2016 drought in the semiarid Northeast Brazil region.

This study discusses the climatological aspects of the most severe drought ever recorded in the semiarid region Northeast Brazil. Droughts are recurrent in the region and while El Nino has driven some of these events others are more dependent on the tropical North Atlantic sea surface temperature fields. The drought affecting this region during the last 5 years shows an intensity and impact not seen in several decades in the regional economy and society. The analysis of this event using drought indicators as well as meteorological fields shows that since the middle 1990s to 2016, 16 out of 25 years experienced rainfall below normal. This suggests that the recent drought may have in fact started in the middle-late 1990s, with the intense droughts of 1993 and 1998, and then the sequence of dry years (interrupted by relatively wet years in 2007, 2008, 2009 and 2011) after that may have affected the levels of reservoirs in the region, leading to a real water crisis that was magnified by the negative rainfall anomalies since 2010.