Semi-arid Region Of Northeast Brazil Research Articles

Geospatial Insights into Aridity Conditions: MODIS Products and GIS Modeling in Northeast Brazil

Northeast Brazil (NEB), particularly its semiarid region, represents an area highly susceptible to the impacts of climate change, including severe droughts, and intense anthropogenic activities. These stresses may be accelerating environmental degradation and desertification of soil in NEB. The main aim of this study was to gain geospatial insights into the biophysical parameters of surface energy balance and actual evapotranspiration on a multi-temporal scale, aiming to detect and analyze the spectral behavioral patterns of areas vulnerable to degradation processes, based on thematic maps at the surface, for NEB and mainly the semiarid region of NEB from 2000 to 2019. Geospatial data from 8-day MODIS sensor products were used, such as surface reflectance (Terra/MOD09A1 and Aqua/MYD09A1), surface temperature (Terra/MOD11A2 and Aqua/MYD11A2), and actual evapotranspiration (Terra/MOD16A2 and Aqua/MYD16A2), version 6. Therefore, in this study, pixel-to-pixel values were processed by calculating the average pixel statistics for each year. From the reflectance product, digital processing of the surface albedo and spectral vegetation indices was also carried out, using computational programming scripts and machine learning algorithms developed via the Google Earth Engine (GEE) platform. The study also presents a seasonal analysis of these components and their relationships over 20 years. Through vegetation indices and statistical correlations, a new predictive model of actual evapotranspiration was developed. The quantitative and spatiotemporal spectral patterns of the parameters were assessed through descriptive statistics, measures of central tendency and dispersion, and statistical error analyses and correlation indices. Thematic maps highlighted the pixel-to-pixel results, with patterns of high temperature distribution mainly in the central and northeastern part of NEB and the semiarid region of NEB, highlighting the formation of persistent heat islands over time. Meanwhile, in these areas, the maps of actual evapotranspiration showed a drastic reduction due to the lesser availability of energy. Over time, the semiarid region of NEB presented areas with little and/or no vegetation cover, which were highly well-defined between the years 2012 and 2019, confirming that these areas are extremely vulnerable to degradation and desertification processes due to significant loss of vegetative and water resilience. The components of energy balance were highly interconnected to climatological and environmental conditions, showing the severe results of drought and accentuation of the water deficit in NEB, presenting a greater condition of aridity in the semiarid region of NEB over time.

Time living with food insecurity and socio-demographic factors: longitudinal analysis in a city in the semi-arid region of Northeast Brazil.

Food insecurity (FI) is the lack of daily access for everyone to quality food in sufficient quantity. In many populations, it presents as a chronic and persistent condition. This study analysed the association between the length of time living with FI and socio-demographic conditions in households in a semi-arid municipality in the Brazilian Northeast between 2011 and 2019. This is a population-based cohort study among families in the municipality in Northeast Brazil (2011, 2014 and 2019). FI was estimated through the Escala Brasileira de Insegurança Alimentar (EBIA, Brazilian Household Food Insecurity Measurement Scale), and the longitudinal category of time of living with FI was adopted to classify them according to the time they remained in FI during the cohort. The association with the socio-demographic profiles of the population was verified through multinomial logistic regression. Households in semi-arid, Northeast of Brazil. Household respondents interviewed in 2011, 2014 and 2019 (n 274). Sixty-seven percentage (67 %) of families lived in FI in this period. Rural residence, low monthly per capita income and low schooling of the household reference person increased the chances of these families living longer in FI. These overlapping conditions increased the odds of FI in the household. Coping with FI requires intersectoral intervention that improves the socio-demographic conditions of the population.

Coinfection with Leishmania infantum and Toxoplasma gondii in Domestic Cats from a Region with a High Prevalence of Feline Immunodeficiency Virus.

The aim of this study was to investigate the coinfection of feline retroviruses (feline immunodeficiency virus-FIV, and the feline leukemia virus-FeLV) with Leishmania infantum and Toxoplasma gondii and the factors associated with these pathogens in domestic cats from Mossoró, a city endemic for canine and human leishmaniasis situated in the semiarid region of Northeast Brazil. Blood samples from 120 cats were collected, and an epidemiological questionnaire was applied to investigate the risk factors associated with the infections. Retroviruses, L. infantum, and T. gondii infections were assessed using a point-of-care ELISA and quantitative PCR (qPCR), indirect fluorescent antibody test (IFAT) and qPCR, and IFAT, respectively. The overall seroprevalences observed were 35% (95% CI = 27.0-43.8%) for FIV, 0.8% (95% CI = 0.1-4.5%) for FeLV, 25.8% (95% CI = 18.8-34.3%) for T. gondii, and 4.2% (95% CI = 1.7-9.3%) for L. infantum. Coinfection with FIV and L. infantum was observed in 2.5% (3/120) of the assessed cats, while 12.5% (15/120) were coinfected with FIV and T. gondii. No significant association was found among the investigated agents (p > 0.05). The factors associated with FIV infection in the multivariable analysis were male sex and age above 78 months. The findings of this study demonstrated a high rate of FIV infection in cats from the Brazilian semiarid region and the exposure of these animals to zoonotic and opportunistic agents. Due to the immunosuppressive potential of FIV, cats infected with this retrovirus should be screened for coinfections with L. infantum and T. gondii, and preventative measures should be adopted.

Short-Term Agronomic and Economic Responses to the Adoption of Cover Crops for Corn Rotation in the Brazilian Semiarid Region

Cover crops (CCs) have demonstrated their significance in enhancing the agronomic and economic performance of corn in succession. In this paper, we assess the agronomic responses and short-term economic returns of adopting cover crops (CCs) for corn cultivation in the sandy soils of the semiarid region of northeast Brazil, with the aim of addressing the additional challenges of CCs adoption in semiarid regions. The field study was conducted in Arapiraca, Alagoas, under no-tillage conditions for two cropping seasons. A randomized complete block design was employed, comprising six CCs (sunn hemp, spectabilis, jack bean, pigeon pea, lab lab, and millet) treatments and one fallow, with 18 replications. The CCs were cultivated for 60 days before corn planting. Drip irrigation was applied during the grain-filling stage of corn growth. Over the two cropping seasons, the biomass and nutrient cycling of the CCs, corn yield, and economic returns were determined, as well as the total organic carbon (TOC) and Mehlich-1 extractable P levels in the soil after corn harvest. The grain yields with sunn hemp, spectabilis, and jack bean were superior (~10%) to that of the fallow (7.7 vs. 7.1 Mg ha−1), irrespective of the cropping season. Sunn hemp exhibited a higher biomass accumulation and ensured greater nutrient cycling, except for K, while lab lab and millet displayed a similar potential, although substantial variations were observed between seasons. Under sunn hemp and jack bean, the TOC increased by ~9%, particularly in the second season. Regarding the available P, spectabilis and jack bean exhibited the highest levels, with an increase of ~74% compared to the fallow (~31.1 vs. 17.9 mg dm−3). Spectabilis and lab lab demonstrated more promising results, both agronomically and economically. However, millet and sunn hemp have the potential to reduce costs over multiple cropping seasons. Therefore, the adoption of cover crops is a sustainable and economically viable agricultural practice. However, it is essential to acknowledge that our results do not represent rainfed conditions and require further investigation.

Workloads, precariousness and worker health in agribusiness in the semi-arid region of Northeast Brazil

RESUMO A expansão do agronegócio no semiárido do nordeste do Brasil tem transformado agricultores camponeses em empregados de empresas de fruticultura, trazendo mudanças para seus modos de vida e trabalho. O estudo objetivou analisar condições, processos e cargas de trabalho no agronegócio de fruticultura. Realizou-se pesquisa qualitativa em que foram entrevistados empregados do agronegócio. As evidências foram produzidas e analisadas a partir de referenciais do campo Saúde do Trabalhador, fundamentando-se na teoria da determinação social do processo saúde-doença e adotando ‘processos de trabalho’ e ‘cargas de trabalho’ como categorias compreensivas das relações entre trabalho e saúde-doença. Observou-se que a produção agrícola se baseia na monocultura, no uso intensivo de mecanização e de agrotóxicos, e segue os moldes organizacionais da acumulação flexível e do taylorismo e fordismo. O mundo do trabalho vivido pelos empregados é marcado por alienação dos trabalhadores, precarização e intensificação do trabalho, que se concretizam em cargas de trabalho físicas, psíquicas, fisiológicas e, sobretudo, químicas. Estas advêm do uso intenso de agrotóxicos, presentes em todos os ambientes e processos de trabalho investigados. A proteção da saúde desses trabalhadores tensiona o Sistema Único de Saúde (SUS) a intensificar a vigilância em Saúde do Trabalhador, e a saúde coletiva, a incluir a problemática da saúde no debate público sobre os modelos agrícolas nacionais.

Hydrocarbon markers for assessing the influence of human activities in the tropical semi-arid region (Acaraú River, state of Ceará, Brazil)

Coastal ecosystems are facing increasing anthropogenic stressors, including rapid urbanization rates and extensive fossil fuel usage. Nevertheless, the distribution of hydrocarbons in the Brazilian semi-arid region remains relatively uncharacterized. In this study, we analyzed ten surface sediment samples (0–2 cm) along the banks of the Acaraú River to assess the chronic contributions of aliphatic and aromatic hydrocarbons. The Acaraú River is a crucial riverine-estuarine area in the semi-arid region of Northeast Brazil. Ultrasound-assisted extraction and gas chromatograph coupled to a mass spectrometer were used to identify target compounds: 45 PAHs, 27 n-alkanes (C10–C38), and two isoprenoids. At most stations, the predominant grain size was sand, and the organic carbon content was less than 1%. The total n-alkanes concentration ranged from 14.1 to 170.0 μg g−1, while individual pristane and phytane concentrations ranged from not detected (nd) to 0.4 μg g−1 and nd to 0.7 μg g−1, respectively. These concentrations resemble those found in unpolluted sediments and are lower compared to samples from urbanized coastal areas. The total USEPA PAHs concentration varied from 157.8 to 1364 ng g−1, leading to the characterization of sediment samples as moderately polluted. Based on diagnostic ratios calculated from both alkane and PAH concentrations, the sediment samples were predominantly deriving from pyrolytic sources, with some contribution from petrogenic sources. The most abundant group was 5-ring PAHs (mean: 47.3 ± 36.7%), followed by 3-ring PAHs (mean: 17.9 ± 13.7%). This predominance indicates a pyrolytic origin of hydrocarbons in the Acaraú River. The concentrations reported here were representative of the level of background hydrocarbons in the region. Regarding the sediment quality assessment, BaP TPE calculated for the Acaraú River ranged from 13.2 to 1258.4 ng g−1 (mean: 409.3 ± 409.4 ng g−1). When considering site-specific sediment quality values for the coast of the state of Ceará, half of the stations are classified as strongly contaminated, and toxic effects are expected to occur (SQGq >0.25) for the ∑16 PAHs measured in the samples, especially due to dibenz [a,h]anthracene concentrations.

Perception of health risks in contexts of extreme climate change in semiarid Northeastern Brazil: an analysis of the role of socioeconomic variables

BackgroundGlobal climate change poses a significant challenge in contemporary society, particularly affecting vulnerable populations like small farmers residing in arid and semiarid regions. This study aims to investigate the perception of health risks and adaptive responses in the semiarid region of Northeast Brazil (NEB). Four questions were formulated: (1) How do socioeconomic factors influence the perception of health risks during extreme climate events? (2) How do socioeconomic factors impact the adoption of adaptive responses to mitigate health risks during extreme weather events? (3) How does the perceived risk level affect the utilization of adaptive responses? (4) What is the influence of extreme climate events on the perceived risks and the adoption of adaptive responses?MethodThe research was conducted in the rural community of Carão, situated in the Agreste region of the State of Pernambuco, NEB. Semi-structured interviews were conducted with 49 volunteers aged 18 and above. The interviews aimed to gather socioeconomic information, including sex, age, income, access to healthcare services, family size, and education level. Additionally, the interviews explored the perceived risks and responses employed during different extreme climate events such as droughts or heavy rainfall. The perceived risks and adaptive responses data were quantified to address the research questions. Generalized linear models were employed to analyze the data for the first three questions, while the nonparametric Mann–Whitney test was used for the fourth question.ResultsThe study found no significant differences in the level of perceived risk and adaptive responses between the two climate extremes. However, the quantity of adaptive responses was found to be directly influenced by the perceived risks, regardless of the type of extreme climate event.ConclusionThe study concludes that risk perception is influenced by various complex factors, including socioeconomic variables, and plays a critical role in the adoption of adaptive responses during extreme climate events. The findings suggest that specific socioeconomic variables have a more pronounced influence on how individuals perceive and adapt to risks. Furthermore, the results indicate a cause-and-effect relationship between perceived risks and the generation of adaptive responses. These findings contribute to a better understanding of the factors shaping risk perception and provide valuable insights for future studies in regions prone to extreme climate events.

Interação genótipo x ambiente e estabilidade em variedades crioulas de feijão de corda em terras secas

ABSTRACT Cowpea (Vigna unguiculata (L.) Walp.) is an excellent crop for research in semi-arid regions, due to its tolerance to high temperatures and water deficit, with satisfactory yields in rain-fed cultivation. The objective this work was to evaluate the genotype x environment (G × E) interaction, adaptability and stability of cowpea landraces used in the Cariri, Paraíba, in the semiarid region of Northeast Brazil. The experiment was carried out under rain-fed conditions in two locations of this region. For all traits evaluated, the G × E interaction was simple, which means that the evaluated landraces can be recommended for the different environments tested. The results also suggest that phenotypic selection can be efficient to enhance the yield of cowpea landraces and, therefore, can be practiced by the farmers themselves. The most advantageous landraces were ranked with good stability (qi <5%). Although the performance standards between the cowpea landraces were similar in the different environments, the best values were obtained on the farm with the best environmental conservation history and with higher precipitation. Therefore, the integration between the yield of cowpea landraces, environmental conservation in agricultural landscapes, and strategic planning that considers possible variations in local precipitation is essential in models of sustainable agricultural development in semi-arid zones of Northeast Brazil.

Relict soil features in cave sediments record periods of wet climate and dense vegetation over the last 100 kyr in a present-day semiarid region of northeast Brazil

The present-day semiarid region of NE Brazil experienced multiple periods of increased precipitation during the Quaternary. They were likely linked to global-scale events (e.g., Heinrich Events) and drove changes in vegetation dynamics, leading to the expansion of rainforest vegetation. Here, we hypothesize that soil features preserved in cave sediments records paleoenvironmental changes induced by global-scale events that affected NE Brazil during the Late Pleistocene - Early Holocene. To test this hypothesis, we analyzed the elemental and isotopic geochemistry composition, bulk sediment mineralogy, soil micromorphological features, and fauna fossil type and content of a well-preserved 6 m cave sediment profile spanning 103 kyr – 8 kyr in Toca de Cima do Pilão at the Serra da Capivara National Park. Our approach provides new information on the history of soil formation, vegetation, and climate of NE Brazil during the Late Pleistocene - Early Holocene. The results demonstrated that severe weathering and dense vegetation was the dominant paleoenvironmental conditions during wet periods, when latosolization was the main soil forming process. The evidence for wet and intense weathering periods was the co-existence of speleothems layers with Ferralsol features, such as runiquartz, granular microstructure, Fe nodules and gibbsite formation. Some of these features were found in layers deposited in synchrony with Heinrich Stadial and Younger Dryas periods, suggesting that past soil processes in NE Brazil were affected by those global-scale events. We propose five phases of latosolization in our study area during the last 100 kyr. The first was identified around 80 kyr, the second occurred around 29 kyr. The third coincided with Heinrich Stadial 1 (16 kyr) and the fourth likely occur during the Younger Dryas, and the fifth phase occurred during the middle Holocene.

Burkholderia semiarida sp. nov. and Burkholderia sola sp. nov., two novel B. cepacia complex species causing onion sour skin

Two putative novel Burkholderia cenocepacia lineages found in the semi-arid region of north-east Brazil causing onion sour skin were studied using genomic approaches to determine their taxonomic position. Four strains belonging to one novel lineage (CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171) and one strain (CCRMBC51) belonging to another novel lineage had their whole genome sequenced to carry out taxogenomic analyses. The phylogenomic tree built using the type (strain) genome server (TYGS) clustered the strains CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171 into the same clade, while grouped the strain CCRMBC51 separately. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) analysis showed values above 99.21 % and 93.2 %, respectively, among the strains CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171, while ANI and dDDH values between these strains and the strain CCRMBC51 were below 94.49 % and 56.6 %, respectively. All these strains showed ANI and dDDH values below 94.78 % and 58.8 % concerning type strains of the B. cepacia complex (Bcc) species. The phylogenetic maximum likelihood tree constructed based on the multilocus sequence analysis of core genes (cMLSA) clustered the strains CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171 and the strain CCRMBC51 in two exclusive clades, which did not cluster with any known species of the Bcc. Therefore, combined data from TYGS, ANI, dDDH, and cMLSA demonstrated that the strains represent two novel species of the Bcc, which we classified as Burkholderia semiarida sp. nov. and Burkholderia sola sp. nov., and proposed the strains CCRMBC74T (=IBSBF 3371 T = CBAS 905 T) and CCRMBC51T (=IBSBF3370T = CBAS 904 T) as type strains, respectively.

Clinical, histopathological, and molecular findings for Mycobacterium avium subspecies paratuberculosis (MAP) in dairy goats under semiarid conditions

The objective of this study was to report the occurrence of Mycobacterium avium subspecies paratuberculosis (MAP) in dairy goats, via description of their clinical presentation, histopathological findings, and molecular identification of the infectious agent. Screening was performed using IS900 real-time PCR (qPCR) in milk samples from 179 properties in the semiarid of Northeast region of Brazil. Pooled milk samples from all lactating goats from processing plants were submitted to molecular diagnosis. One property had a positive result at qPCR. The production unit which had the positive sample for MAP was located, and an on-site visit to this property was performed to collect individual milk samples, seven of which tested MAP positive by IS900 qPCR. With permission from the owner, two goats (Animal 1 was positive and Animal 2 was negative on first qPCR for MAP) were acquired and euthanized. Animals 1 and 2 had milk and portions of the duodenum, ileum, colon, and mesenteric lymph nodes positive at qPCR for MAP. Animal 1 also had MAP DNA detected in part of the jejunum and cecum. In animal 2, the ileocecal valve tested positive. MAP was not detected in the blood or feces of either animal; however; it was confirmed for the association of clinical findings, histopathology, and qPCR. The gene IS900 from the positive samples were sequenced and showed a 99% similarity with MAP. The MAP was identified for the first time in the goat milk and tissues in the semiarid region of Northeast Brazil.

Endoparasites in domestic cats (Felis catus) in the semi-arid region of Northeast Brazil.

The aim of this study was to evaluate the prevalence of endoparasites in domestic cats (Felis catus) in the city of Sousa, state of Paraíba, Northeast Brazil. A total of 207 samples of fresh feces were randomly collected from domestic and semi-domiciled cats. The samples were analyzed by simple centrifugation and centrifuge-flotation in sucrose solution for the diagnosis of helminth eggs and enteric protozoan oocysts and cysts. Epidemiological information was obtained to determine risk factors related to infections. Among the samples collected, 81.6% (169/207; 95% CI: 77.4-83.8) were positive for at least one parasite genus. Ancylostoma spp. was the most prevalent, at 67.1% (139/207), followed by Taenia spp. at 28.5% (59/207), and Spirometra spp. and Platynosomum sp., both at 17.3% (36/207). The variables associated with helminth infection were a historic lack of deworming (Odds ratio = 12.25) and the presence of dry fur (Odds ratio = 2.15). No risk factors were observed for enteric protozoa infection. This study demonstrated a high prevalence of endoparasites in domestic cats in the city of Sousa, state of Paraíba, and associated risk factors, thus establishing an overview of the main helminths and protozoa that affect cats in this region.

Functional threshold responses of benthic macroinvertebrates to environmental stressors in reservoirs

Reservoirs are aquatic ecosystems created by humans to supply water needs. They can impair aquatic diversity due to the lack of connectivity, reduced water volume, and pressures exerted by surrounding human activities. These changes are expected to produce abrupt fluctuations in the reservoirs' environment, thus influencing the structure and functioning of aquatic communities. Therefore, this study aimed to understand the impact of a range of environmental stressors in reservoirs on benthic macroinvertebrates by analyzing their functional threshold response. Biological data were collected in six reservoirs from the semi-arid region of Northeast Brazil, as case study. A total of 37.874 benthic macroinvertebrates belonging to 35 taxa were collected. Nevertheless, almost 90% of this abundance belonged to three species alone, considered generalists, with multivoltine reproduction and from the gatherer-collectors feeding group. Increases in environmental stressors such as salinity, nitrate, ammonia, and dissolved solids led to the selection of macroinvertebrates with specific traits (e.g., protected body, gill respiration, and large body size). These functional traits showed differences in their threshold response depending on the stressors and are indicators of the effects of these stressors on the reservoirs. Some of the potential sensitive traits (with a negative threshold response to the stressor) could also associate with other stressors, demonstrating that tolerance of benthic macroinvertebrates is defined by a set of functional characteristics. Overall, the increase in stressor’ gradients selected functionally tolerant organisms with high resistance capacity, but these were represented by dominant species. This resulted in low diversity in the reservoirs, which may compromise ecosystem functioning, and raises concerns about adequate management of the systems.

Piruvato de cálcio como mitigador do estresse salino em mudas de maracujazeiro amarelo

ABSTRACT Although the semi-arid region of Northeast Brazil is a major producer of yellow passion fruit, the problems of salts in the soil and water sources, in many areas have limited the growth and production of this crop, which highlights the importance of studies aimed at reducing such effects. In this context, the objective of this study was to evaluate the effect of foliar application of pyruvate, as a mitigator of salt stress, on the morphophysiology of yellow passion fruit, in seedling phase. The treatments consisted of three electrical conductivities of irrigation water (ECw: 0.8, 2.4, and 4.0 dS m-1) and three concentrations of pyruvate (0, 25, and 50 mM), distributed in a randomized block experimental design in a 3 × 3 factorial scheme, with four replications and two plants per plot. Irrigation with ECw of 4.0 dS m-1 reduces growth variables, phytomass, Dickson quality index, and increases electrolyte leakage in passion fruit seedlings cv. Redondo Amarelo. Exogenous application of calcium pyruvate (25 and 50 mM) increased growth, phytomass, Dickson quality index, relative water content and leaf succulence and reduced electrolyte leakage in the leaf blade in passion fruit. Exogenous application of pyruvate attenuates salt stress, with beneficial effects on CO2 assimilation rate, transpiration, instantaneous carboxylation efficiency, intrinsic water use efficiency, and root dry mass.

The reterritorialization and the struggle for water of those affected by the transfer of the São Francisco River in the Brazilian Northeast

The implementation of the largest Brazilian hydrological project, theProjeto de Integração do rio São Francisco –PISF (water resources project implemented by the federal government in the Brazilian Northeast), responsible for transfering the river's waters into the semi-arid Northeast region of Brazil, had different effects in the region and caused the deterritorialization of several families. A portion of these families were reterritorialized into the 18 rural villages scattered throughout the project, where approximately 845 families were resettled. In this context, the research conducted in the rural village of Lafayette, in Monteiro/PB, aims to analyze the process of reterritorialization of the affected actors and their strategies to fight for access to water. For this purpose, we adopted a qualitative approach and ethnographic research, using procedures such as oral history interviews with actors resettled in the village, semi-structured interviews with institutional actors, in addition to collecting documents, photographs and observations recorded in the field diary. The results demonstrate the difficulties faced by families in the process of reterritorialization in the village, the emergence of conflicts over water, in addition to apprehending the different strategies of struggle of the affected actors to obtain access to water for human consumption. In this way, the study contributes to the problematization regarding those affected by the project and the access to water within such a large project whose motto is the distribution of water, though the lives of the affected families remain barren.

Initial Studies of the Response of Rubber Tree Seedlings Treated with Saprobic Fungi from the Semiarid Region of Northeast Brazil to Anthracnose.

Anthracnose, caused by fungi of the genus Colletotrichum, is present in the main areas where rubber trees (Hevea brasiliensis) are planted. Thus, considering that biological agents can be an alternative for disease control, the present study aimed to carry out initial studies to investigate the response of rubber tree seedlings inoculated with Colletotrichum and treated with saprobes fungi from the semiarid region of Northeast Brazil (Curvularia eragrostidis, Memnoniella levispora, Myrothecium roridum and Phialomyces macrosporus). Seedlings of the rubber tree clone RRIM600 were sprayed with biocontrol agents as preventive and curative treatments seven days before and after C. tamarilloi inoculation, respectively. Assessments included plant response to disease expression based on the percentage of symptomatic area on treated leaves, percentage of graft death, and percentage of apical death in seedlings 30 days after inoculation with C. tamarilloi. In addition, the enzymes peroxidase and phenylalanine ammonia lyase (PAL) had their activity quantified by their association with plant resistance to pathogens. The fungus C. eragrostidis had the best result in controlling anthracnose when applied as a preventive treatment, showing 10% less disease than the untreated plant. The same was observed for the fungus P. macrosporus when used in the curative form. These fungi also reduced the graft death. In these cases, PAL activity was higher and may be linked to the induction of resistance against the pathogen. The peroxidase activity was not expressive for treatments with saprobic fungi in the periods studied. Therefore, among the tested fungi, C. eragrostidis and P. macrosporus are promising for the control of anthracnose, deserving further studies.

Organic matter pools in a fluvisol after 29 years under different land uses in an irrigation region in northeast Brazil

Soil organic matter (SOM) is a critical component of the soil system and a sensitive indicator of soil quality. We aimed to investigate the response of SOM pools to different land uses and management in irrigated croplands of the semi-arid region of northeast Brazil. Four sites irrigated under long-term (29 years) land uses were selected: banana (B1 and B2); elephant grass (EG) - perennial systems; maize and cowpea succession (MCP) - annual system; B1 was cropped for 17 years +2 years of maize and cowpea +17 years banana, while B2 was continuously cropped. A native forest (NF) site was selected as reference of steady state. Soil samples were collected at four depths in the rows and inter-rows of each management system. The higher decline in SOM fractions was perceived at 0–0.05 m depth and microbial indices (microbial biomass C and N, and basal respiration and metabolic quotient) were very sensitive indicators of soil quality. Perennial systems (B1 and EG) maintained the C and N stocks at higher levels equivalent to NF at the 0–0.40 m layer, while MCP and B2 had lower total organic carbon (TOC) (15 and 17%, respectively) and total nitrogen stocks (4.27 and 8.67%, respectively). Perennial cultivation with B1 and EG showed also the highest soil C and N microbial biomass and stratification ratio and, the lowest respiratory quotients, all indications of elevated soil C sequestration. In general, land use change from native forest to annual crops reduced plant residue input and increased soil disturbance, favoring higher SOM mineralization, while perennial crops and grasses were the most effective in increasing C and N stocks due to the maintenance of crop residues on the soil surface and the absence of soil tillage.

Peróxido de hidrogênio como atenuador do estresse salino na fisiologia e biomassa de maracujazeiro amarelo

ABSTRACT The success of yellow passion fruit cultivation in the semi-arid region of Northeast Brazil is conditioned on the ability of this crop to develop under salt stress conditions, so it is necessary to identify techniques capable of attenuating the deleterious effects caused by irrigation with high-salinity waters. In this context, the present study aimed to evaluate the fluorescence, photosynthetic pigments and biomass of yellow passion fruit cultivated under salt stress and foliar application of hydrogen peroxide. The study was conducted in a greenhouse, with the experimental design in randomized blocks with three replicates, in a 4 × 4 factorial scheme, which consisted of four values of irrigation water electrical conductivity - ECw (0.7, 1.4, 2.1 and 2.8 dS m-1) and four concentrations of hydrogen peroxide (0, 20, 40 and 60 µM). Irrigation using water with ECw from 1.4 dS m-1 compromised the photochemical efficiency, photosynthetic pigments, and biomass production of yellow passion fruit. Application of hydrogen peroxide at concentration of 20 µM promoted the highest values for variable and maximum fluorescence and concentration of carotenoids, constituting an alternative for the acclimation of yellow passion fruit to salt stress. Application of hydrogen peroxide at concentrations above 20 µM intensified the salt stress on passion fruit.

Assessment of soil salinity status under different land-use conditions in the semiarid region of Northeastern Brazil

Soil salinization and sodification, caused by inadequate land management, is one of the main threats to the semiarid agroecosystems. It is essential to investigate saline levels under different land-use conditions to maintain the sustainability of agricultural production. The main objective of this study was to diagnose the salinity status of the soil in different land-use conditions in the semiarid region of Northeast Brazil. Soil samples were collected in the surface layer (0–5 cm) of three different land-use conditions: areas of low salinity (native vegetation – Caatinga), areas of different saline levels (cultivated areas), and areas of very high salinity (desertified by salinity), and compared regarding the chemical attributes of the soils by descriptive and multivariate analysis. The results showed that sodium and chloride were the predominant soluble ions in cultivated and desertified areas due to saline waters commonly used in the study region. Increases in electrical conductivity values of 1219 and 23207% were observed for cultivated and desertified areas, respectively, compared to areas of native vegetation. The principal component analysis contributed to identifying parameters responsible for the variation in soil salinity, and the second factor identified that percentage of exchangeable sodium, electrical conductivity, and exchangeable and soluble sodium plays an essential role in soil desertification. However, calcium, magnesium, sodium, and chloride ions correlated positively with variables that degrade soils - EC, ESP, and SAR. We also found that in desertified areas, in addition to chloride, sulfate is also present in expressive levels, and due to the strong associations with calcium, magnesium, and sodium, our study suggests that in addition to the free forms of these ions, the forms of chlorides and sulfates of calcium, magnesium, and sodium also effectively contribute to the degradation of the areas. The combination of multivariate analysis × geochemistry × laboratory techniques was a valuable tool to identify and monitor saline levels in converting uncultivated to cultivated areas and from cultivated areas to desertified areas.

Development of a methodological approach to estimate vegetation biomass using remote sensing in the Brazilian semiarid NE region.

The accurate estimation of vegetation biomass over large areas is still a significant challenge. The evolution of low-cost geotechnologies is rapidly facilitating this task, but their use to estimate biomass on tropical dry forests (TDFs) is still scarce. TDFs cover large areas and are currently among the most threatened global ecosystems due to intense anthropic pressures. Therefore, there is a need for the development of tools capable of monitoring the complex spatial-temporal dynamics of these highly variable ecosystems. We developed a methodology to estimate aboveground biomass stocks in a tropical dry forest (known as “Caatinga”), native to the semiarid region of Northeast Brazil, using field and orbital data, regression models, and high-performance computation. We combined twenty types of vegetation spectral indices and isolated spectral bands of the Landsat 8 satellite OLI sensor to generate regression model equations that could predict biomass stocks. The selected models were applied in a cloud processing routine developed using Google Earth Engine (GEE) to estimate the biomass (30 m pixel resolution) in the entire semiarid region of Pernambuco state (85,900 km2), using the years 2017 and 2018 as references. The regression models were capable of predicting the biomass in dense Caatinga (μ 32.6 Mg ha−1 - R2 0.52), open Caatinga (μ 11.4 Mg ha−1- R2 0.56), and pasturelands (μ 4.2 Mg ha−1-R2 0.94). Using the equations previously defined and the map of the Brazilian Annual Coverage and Land Use Mapping (Mapbiomas) we developed a workflow script in GEE to plot a map that represents the biomass stock over the entire semiarid region of Pernambuco. The system plotted the distribution and amount of biomass with similar results to those available in the literature. Given the large area of the region, the biomass was estimated with reasonable precision in spatial and temporal distribution, while demanding little time and hardware costs. Future refinements of the method will be pursued, but the proposed version represents an improvement in the capability to provide reliable estimates and contributes to monitor the biomass dynamics in the in semiarid region of NE Brazil.