ABSTRACT Chrysanthemum (Dendranthema grandiflora) is the second most produced and commercialized ornamental plant in the world. Measuring leaf area through non-destructive methods is fundamental for studies on its growth and production. The estimation of leaf area by linear dimensions of the leaves can be a strategy for this purpose. The objective of this study was to find allometric equations to estimate the leaf area of chrysanthemum. The linear, linear without intercept, quadratic, cubic, power, and exponential regression models were used for the analysis. The choice of equations was based on the highest coefficients of determination. The non-destructive method using allometric models has accuracy for estimating the leaf area (LA) of chrysanthemum from the product between leaf length (L) and leaf width (W). The LA of chrysanthemum can be estimated using the equation ŷ = 0.6611*LW0.9490 (L - leaf length; W - leaf width). This equation will allow researchers and producers to determine leaf area non-destructively.

RESUMO O crisântemo (Dendranthema grandiflora) é a segunda planta ornamental mais produzida e comercializada no mundo. A medição da área foliar por métodos não destrutivos é fundamental para estudos sobre seu crescimento e produção. A estimativa da área foliar por dimensões lineares das folhas pode ser uma estratégia para este fim. O objetivo deste estudo foi encontrar equações alométricas para estimar a área foliar do crisântemo. Os modelos de regressão linear, linear sem intercepto, quadrático, cúbico, potência e exponencial foram utilizados para a análise. A escolha das equações foi baseada nos maiores coeficientes de determinação. O método não destrutivo por meio de modelos alométricos tem acurácia para estimar a área foliar (AF) do crisântemo a partir do produto entre o comprimento da folha (C) e a largura da folha (L). A AF do crisântemo pode ser estimada pela equação ŷ = 0,6611*CL0,9490 (C - comprimento da folha; L - largura da folha). Essa equação permitirá que pesquisadores e produtores determinem a área foliar de forma não destrutiva.

ABSTRACT Salinity can have detrimental effects on plant development. To minimize this damage, strategies such as balanced maintenance of plants’ nutritional status have been proposed previously. The objective of this study is to investigate whether the optimization of foliar nitrogen fertilization can promote the growth and photochemical efficiency of purple basil subjected to salt stress. The experiment was performed using a randomized block design with an incomplete 5 × 5 factorial arrangement generated through experimental matrix Central Composite Design with two parameters: salinity of irrigation water at 0.5, 0.81, 2.75, 4.69, and 5.50 dS m-1; and nitrogen doses at 0, 58.58, 200, 341.42, and 400 mg L-1. It was found that an increase in the salinity of irrigation water reduced the growth and photochemical efficiency of purple basil. However, the foliar application of nitrogen at the concentration of 400 mg L-1 attenuated the harmful effects of salinity on both the absolute and relative growth rates of stem diameter, the relative growth of plant height, and chlorophyll A fluorescence. These results showed that foliar nitrogen fertilization is a suitable strategy to help mitigate salt stress in basil plants.

RESUMO A salinidade pode promover efeitos danosos ao desenvolvimento vegetal, sendo o necessário o uso de estratégias para minimizar os danos promovidos, como a manutenção equilibrada do estado nutricional da planta. Assim, o objetivo deste estudo foi avaliar o efeito da adubação nitrogenada foliar e da salinidade no crescimento e eficiência fotoquímica de manjericão roxo. O experimento foi conduzido com o delineamento de blocos casualizados, em arranjo fatorial incompleto 5 × 5 (salinidades da água de irrigação: 0,5; 0,81; 2,75; 4,69 e 5,50 dS m-1 × doses de nitrogênio: 0; 58,58; 200; 341,42 e 400 mg L-1), gerados através da matriz experimental Composto Central de Box. O aumento da salinidade da água de irrigação reduz o crescimento e a eficiência fotoquímica das plantas de manjericão roxo. Todavia, a aplicação foliar de 400 mg L-1 de N atenuou os efeitos deletérios da salinidade sobre as taxas de crescimento absoluto e relativo para o diâmetro do caule e relativo para a altura de plantas, assim como na fluorescência da clorofila a. Esses resultados mostram que a adubação foliar nitrogenada é uma estratégia para mitigar o estresse salino em plantas de manjericão.

Abstract Information from Pereskia aculeata Miller (Cactaceae) responses regarding the portion of the stem cuttings branch parental plants and the shading level need to be investigated in order to establish techniques for their producing seedlings. We aimed was to evaluate the effect of cutting types and shading levels in the production of P. aculeata seedlings. We studied three cutting types, collected from different portions of the stem cuttings branch: herbaceous, semi-hardwood, and hardwood, which were arranged under two shading levels: 0% (full sun) or 50% (shade). The selected parent plants had an adequate and vigorous phytosanitary aspect. After 90 days after the cuttings, the seedlings were evaluated regarding survival, growth indicators, biomass production and partitioning, and allometric indices. Seedlings from hardwood cuttings and produced under 0% shading showed higher survival. The largest number of sprouts occurred in seedlings of semi-hardwood and hardwood cuttings. The highest leaf area values occurred in seedlings of semi-hardwood and hardwood cuttings under 0% shading. Seedlings from hardwood cuttings had higher biomass allocation in the roots under 50% shading. Seedlings of herbaceous and semi-hardwood portion allocated values ≥ 70% of the biomass in the aerial part. Seedlings of species are able to adjust to different shading levels as a plasticity mechanism. For the production of P. aculeata seedlings, the hardwood portion of the stem cuttings branch under full sun cultivation is recommended. In addition, semi-hardwood cuttings grown under 50% shading can also be used for seedlings production.

Resumo Informações das respostas da Pereskia aculeata Miller. (Cactaceae) quanto à porção da estaca do ramo da planta matriz e o nível de sombreamento precisam ser investigadas com o intuito de estabelecer protocolos para sua produção de mudas. Objetivamos avaliar o efeito do tipo de estaca e níveis de sombreamento na produção de mudas de P. aculeata. Estudamos três tipos de estacas baseados na porção de coleta do ramo: herbácea, semi-lenhosa e lenhosa, acondicionadas sob dois níveis de sombreamento: 0% (pleno sol) ou 50% (sombra). As plantas matrizes selecionadas tiveram aspecto fitossanitário adequado e eram vigorosas. Após 90 dias da estaquia, as mudas foram avaliadas quanto a sobrevivência, indicadores de crescimento, produção e particionamento de biomassa e índices alométricos. Mudas provenientes de estacas lenhosas e produzidas sob 0% de sombreamento tiveram maior sobrevivência. Os maiores números de brotos ocorreram nas mudas de estacas da porção semi-lenhosas e lenhosa. As maiores áreas foliares e radiculares ocorreram nas mudas de estacas semi-lenhosas e lenhosas sob 0% de sombreamento. Mudas provenientes de estacas da porção lenhosa tiveram maior alocação de biomassa nas raízes sob 50% de sombreamento. Mudas de estacas da porção herbáceas e semilenhosas alocaram valores ≥ 70% de biomassa da parte aérea. As mudas da espécie são capazes de se ajustar aos diferentes níveis de sombreamento como mecanismo de plasticidade. Para a produção de mudas de P. aculeata¸ recomenda-se utilizar a porção lenhosa do ramo do caule sob pleno sol. Além disso, estacas semi-lenhosas crescidas sob 50% de sombreamento podem ser utilizadas para a produção de mudas.

ABSTRACT Lisianthus (Eustoma grandiflorum) has been attracting great interest due to the beauty of the colors of flowers, the firmness of stems, and postharvest durability. However, knowledge of lisianthus irrigation and fertigation has generally been based on recommendations from other countries. This study aimed to establish parameters for the rational management of lisianthus fertigation under a protected environment by determining the best lower limit of soil moisture, associated with the determination of the optimal potassium concentration to be maintained in the soil solution. The treatments consisted of five soil moisture limits for the start of irrigation and maintenance of five potassium concentrations in the soil solution, with four replications. Plots of 0.7 by 0.5 m were arranged in a completely randomized block design in a factorial scheme. The soil solution was monitored by measuring moisture as well as potassium (K+) concentrations using a TDR100 reflectometer and solution extractors, respectively, during two cycles. The evaluated variables were the leaf area index, shoot fresh and dry matter, commercial yield, and average stem diameter. Lisianthus cultivation under the lower limit of soil moisture equal to 0.20 cm3 cm−3 ensured the best results for all variables of commercial interest. No effect of potassium concentrations was observed on variables of commercial interest.

Abstract This study aimed to assess the mental health of a University community in South Brazil during the COVID-19 pandemic. A cross-sectional web-based survey was conducted between July-August 2020 through a self-administered questionnaire. All University staff and students were eligible. Depression was measured using the Patient Health Questionnaire-9 and anxiety by the Generalized Anxiety Disorder-7. To evaluate the effect of social distancing and mental health factors on outcomes, Poisson regression models with robust variance were performed, estimating Prevalence Ratios (PR) and 95% Confidence Intervals (95%CI). 2,785 individuals participated in the study. Prevalence of depression and anxiety were 39.2% (95%CI 37.3-41.1) and 52.5% (95% CI 50.6-54.4), respectively. Undergraduate students showed a higher prevalence of the outcomes. Not leaving the house routinely, mental health care, and previous diagnosis of mental illness were associated with both outcomes. Those with a previous medical diagnosis of depression had a 58% (PR 1.58; 95%CI 1.44; 1.74) and anxiety a 72% (PR 1.72; 95%CI 1.56; 1.91) greater prevalence of depression than their peers. An alarming prevalence of psychopathologies was observed. Despite the well-known benefits of social distancing to public health, it requires a surveillance on the population’s mental health, especially students and those with previous mental illness diagnosis.

Abstract The limitation in the quality of water sources for irrigation in the semi-arid region of northeastern Brazil is increasingly present, so it is necessary to use water with high concentrations of salts for agricultural production, which makes the use of elicitors essential to mitigate the harmful effects of salinity on plants. Given the above, the objective of this study was to evaluate the effects of foliar application of salicylic acid on the mineral composition and production of guava plants under salt stress conditions in the post-grafting phase. The experiment was carried out under greenhouse conditions, in a randomized block design, in a 2 × 4 factorial scheme, with two levels of electrical conductivity of irrigation water (0.6 and 3.2 dS m-1) and four concentrations of salicylic acid (0, 1.2, 2.4, and 3.6 mM), with three replicates. During the flowering stage of guava, N, P, and K contents accumulated in the leaves according to the following order of concentration: N > K > P. Foliar application of 1.2 mM of salicylic acid increases the leaf contents of N, P, and K in guava plants grown under irrigation with water of 0.6 dS m-1. Water salinity of 3.2 dS m-1 reduces the growth and production components of guava plants.

Resumo A limitação na qualidade das fontes hídricas para irrigação na região semiárida do Nordeste é cada vez mais presente, tornando-se necessário o uso de águas com altas concentrações de sais para produção agrícola, o que torna indispensável à utilização de elicitores para atenuar os efeitos deletérios da salinidade sobre as plantas. Diante do exposto, objetivou-se com esse trabalho avaliar os efeitos da aplicação foliar de ácido salicílico na composição mineral e na produção de plantas de goiabeira sob condições de estresse salino na fase pós-enxertia. O experimento foi conduzido em casa de vegetação, no delineamento experimental de blocos casualizados, em esquema fatorial 2 × 4, sendo dois níveis de condutividade elétrica da água de irrigação (0,6 e 3,2 dS m-1) e quatro concentrações de ácido salicílico (0; 1,2; 2,4 e 3,6 mM), com três repetições. Durante a fase de floração da goiabeira, os teores de N, P, K, se acumularam nas folhas segundo a ordem de concentração N > K > P. A aplicação foliar de 1,2 mM de ácido salicílico aumentou os teores foliares de nitrogênio, fósforo e potássio nas plantas de goiabeira cultivadas sob irrigação com água de 0,6 dS m-1. A salinidade da água de 3,2 dS m-1 diminuiu o crescimento e os componentes de produção das plantas de goiabeira.

Abstract Sugarcane is one of the largest agricultural commodities when considering the export volume and the number of jobs generated. Sugarcane production in the Brazilian Northeast region is generally low due to several factors, including the irregular rainfall distribution, which highlights the importance of studies aimed at mitigating the deleterious effects of water stress. In this scenario, this study aimed to evaluate calcium pyruvate as a water deficit attenuator on the agro-industrial quality of sugarcane in the second cycle of cultivation. The experiment was conducted out under greenhouse conditions of the Federal University of Campina Grande, where five sugarcane commercial genotypes tested (G1- RB863129, G2- RB92579, G3- RB962962, G4- RB021754, and G5- RB041443) and three irrigation management strategies (E1- full irrigation, E2- water deficit with application of 30 mM of calcium pyruvate, and E3- water deficit without calcium pyruvate application), distributed in randomized blocks in 5 × 3 factorial arrangement with three replications. The RB021754 genotype under water deficit and without foliar application of calcium pyruvate increased the fiber content (13.2%) and the sugarcane moist cake weight (143.5 g). The effects of water deficit in sugarcane genotypes are attenuated by the exogenous application of 30 mM of calcium pyruvate, with benefits on the polarized sucrose content, apparent sucrose content of the juice, soluble solids content, purity, corrected cane POL, total recoverable sugars, and stem mass in relation to plants under water deficit without calcium pyruvate application.

Resumo A cana-de-açúcar é uma das maiores commodities agrícolas, quando se considera o volume de exportação e o número de empregos gerados. A produção no Nordeste brasileiro, em geral, é baixa, decorrente de diversos fatores, entre eles, a irregularidade de distribuição das chuvas, o que realça a importância de estudos com vistas a minorar os efeitos deletérios do estresse hídrico. Nesse cenário, objetivou-se avaliar o piruvato de cálcio como atenuante do déficit hídrico sobre a qualidade agroindustrial da cana-de-açúcar no segundo ciclo de cultivo. O experimento foi conduzido em casa de vegetação da Universidade Federal de Campina Grande, onde foram testados cinco genótipos de cana-de-açúcar (G1- RB863129, G2- RB92579, G3- RB962962, G4- RB021754 e G5- RB041443) submetidos a três estratégias de manejo da irrigação (E1- Irrigação plena, E2- déficit hídrico com aplicação de 30 mM de piruvato de cálcio e E3- déficit hídrico sem aplicação de piruvato de cálcio), distribuídos em blocos casualizados, em esquema fatorial 5 × 3, com três repetições. O genótipo RB021754 sob déficit hídrico e sem aplicação foliar do piruvato de cálcio aumentou o teor de fibra (13,2%) e o peso do bolo úmido da cana (143,5 g). Os efeitos do déficit hídrico em genótipos de cana-de-açúcar são atenuados com aplicação exógena de 30 mM de piruvato de cálcio, com benefícios sobre o teor sacarose polarizada, teor de sacarose aparente do caldo, teor de sólidos solúveis, pureza, pol da cana corrigida, açúcares totais recuperáveis e massa de colmos, em relação as plantas sob déficit hídrico sem aplicação de piruvato de cálcio.

Abstract In the cropping systems that integrate the corn crop, the insertion of Crotalaria ochroleuca G. Don is predominantly intercropped. In this context, there is a need to observe herbicides that present selectivity for this sunn hemp species. The objective of this study was to evaluate the selectivity of pre and post-emergent herbicides on C. ochroleuca. Two field experiments were conducted in randomized blocks with four replications, involving the pre-emergence and post-emergence application of different herbicide treatments. For the pre-emergent ones, amicarbazone, atrazine and flumioxazin provided phytotoxicity higher than 90% and, consequently, low plant biomass. On the other hand, acetochlor and s-metolachlor did not cause phytotoxicity and did not affect the dry mass of crotalaria. In post-emergence, atrazine + mesotrione showed phytotoxicity >95%, followed by nicosulfuron and 2.4-D with phytotoxicity between 50-60%, whereas tembotrione did not cause injury to the plants. Thus, it was found that among the pre-emergent, acetochlor and s-metolachlor were selective, and for the emerging powders, only tembotrione was the most selective for all parameters analyzed.

Resumo Nos sistemas de cultivo que integram a cultura do milho, a inserção de Crotalaria ochroleuca G. Don é predominantemente consorciada. Nesse contexto, há a necessidade de se observar herbicidas que apresentem seletividade para esta espécie de crotalária. O objetivo deste trabalho foi avaliar a seletividade de herbicidas pré e pós-emergentes sobre C. ochroleuca. Dois experimentos de campo foram conduzidos em blocos casualizados com quatro repetições, envolvendo a aplicação de diferentes tratamentos herbicidas em pré-emergência e pós-emergência. Para os pré-emergentes, amicarbazone, atrazina e flumioxazin proporcionaram fitotoxicidade superior a 90% e, consequentemente, baixa biomassa vegetal. Por outro lado, o acetocloro e o s-metolacloro não causaram fitotoxicidade e não afetaram a massa seca da crotalária. Em pós-emergência, atrazina + mesotrione apresentou fitotoxicidade >95%, seguido de nicosulfuron e 2,4-D com fitotoxicidade entre 50-60%, enquanto o tembrotrione não causou danos às plantas. Assim, verificou-se que entre os pré-emergentes, o acetocloro e o s-metolacloro foram seletivos, e para os pós emergentes, apenas o tembotrione foi o mais seletivo para todos os parâmetros analisados.

Background Eucalyptus is the primary cultivated wood species in Brazil, covering 7.5 million hectares. Weed competition in eucalyptus plantations reduces yield and increases operational costs. FuturaGene/Suzano has developed genetically modified (GM) eucalyptus varieties with glyphosate herbicide tolerance (HT) as a modern tool for improving weed management practices in plantations. The first event received regulatory approval for commercial deployment in 2021. However, the introgression of a new GM trait into eucalyptus, a non-isogenic species, cannot be achieved through selfing or backcrossing. To overcome this limitation and expedite the introgression of HT into the breeding population, multiple GM events were generated, in various genetic backgrounds and genomic locations, enabling simultaneous crossing with numerous elite parents. Objective To characterize the newly developed HT GM eucalyptus events and assess their safety for the environment and wood production. Methods HT GM eucalyptus events were subjected to genome sequencing and glyphosate tolerance testing. Biosafety analyses and environmental impact assessments were conducted through field trials in various eucalyptus cultivation regions, comparing the HT GM eucalyptus with conventional clones. Results The new events proved highly tolerant to glyphosate and displayed different genomic insertion sites. No adverse effects on non-target organisms were observed, and there were no significant differences in the soil microbiota or decomposition profile.Conclusions: The HT GM events have been proven to be safe, posing a low risk to the environment, humans, and animals. Consequently, these HT GM eucalyptus varieties can be confidently utilized for wood production.

RESUMO Embora a região semiárida do Nordeste brasileiro seja uma grande produtora de maracujá amarelo, os problemas de sais no solo e nas fontes hídricas, em muitas áreas, têm limitado o crescimento e a produção dessa cultura, o que realça a importância de estudos visando a reduzir tais efeitos. Nesse contexto, objetivou-se com este estudo, avaliar o efeito da aplicação foliar de piruvato, como mitigador do estresse salino, sobre a morfofisiologia do maracujazeiro cv. Redondo Amarelo, em fase de mudas. Os tratamentos constaram de três condutividades elétricas da água de irrigação (CEa: 0,8, 2,4 e 4,0 dS m-1) e três concentrações de piruvato (0, 25 e 50 mM), distribuídos em delineamento experimental de blocos casualizados, em esquema fatorial 3 × 3, com quatro repetições e duas plantas por parcela. A irrigação com águas de CEa de 4,0 dS m-1 reduz as variáveis de crescimento, fitomassa, indice de qualidade de Dickson e aumenta o extravasamento de eletrólitos em mudas de maracujazeiro cv. Redondo Amarelo. A aplicação exógena de piruvato de cálcio (25 e 50 mM) favorece as variáveis de crescimento, fitomassa, indice de qualidade de Dickson, teor relativo de água, suculência foliar e reduz o extravasamento de eletrólitos no limbo foliar do maracujá. A aplicação exógena de piruvato atenua o estresse salino, com efeitos benéficos na taxa de assimilação de CO2, transpiração, eficiência da carboxilação instantânea, eficiência intrínseca do uso da água e massa seca das raízes.

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.

Ambuic acid (AA) is a highly-modified cyclohexenone and known as a promising inhibitor of quorum sensing in methicillin-resistant Staphylococcus aureus, and is thus a candidate as an antivirulence drug. This molecule is mainly produced by the species of Pestalotiopsis and, since its discovery twenty years ago, only a restricted amount of AA-derivatives have been described. Despite being a promising subject, methods for the analysis of modified AA-analogues via mass spectrometry remain unexplored. In order to adress this question, the marine fungus Pestalotiopsis sp. 4A11 associated with the ascidian Didemnum perlucidum was grown in a solid rice medium and its crude extract was chemically studied. From this extract, AA and 10-hydroxy ambuic acid (10-HAA) were isolated and identified using NMR spectroscopy with the aim of obtaining model compounds for the MS analysis. These served as reference compounds (seeds) to guide the dereplication of other AA-analogues via LC-MS/MS-based molecular networking. Based on the manual interpretation of the fragmentation pathways of the seeds and related compounds observed in the networks, six AA-derivatives were dereplicated in the extract. Furthermore, three analogues with unprecedented chemical formulas were proposed as putative unprecedented AA-derivatives. The fragmentation annotation proposed represents a fast and feasible method for characterizing AA-derivatives.

Abstract The continental margin off the southeastern Brazilian coast is punctuated by a series of geological-geomorphological features, such as subsurface saline diapirs and pockmarks at the seafloor interface, which evidence the abundant presence of oil and gas in the region. In several of these sites, hydrocarbons can be naturally released into the water column, areas are cold seep areas. These are marked by the presence of oil- and gas-dependent ecosystems, where specific organisms are able to fix carbon from hydrocarbon chemosynthesis. In addition, light hydrocarbon fluid flow through the sediment may build up authigenic carbonates that can be further colonized by cold-water corals, generating large carbonate mounds over geological time, normally positioned at the border of these pockmark features. The present work reports on a multidisciplinary oceanographic cruise carried out in the Santos Basin, SW Atlantic, to seek, map, and collect geological, chemical, and biological data from different deep-sea habitats. The cruise occurred in November 2019 on the R/V Alpha Crucis of the Oceanographic Institute of the University of São Paulo (IOUSP). We intended to discover and detail different geomorphological features, characterize free-living and symbiotic microorganisms, determine the chemosynthetic rates in relation to heterotrophic microbial production, and characterize the fauna and study their ecological and evolutionary links within and across ocean basins. All discoveries made during the cruise and their respective results will be presented separately in several papers that comprise this special volume.

Resumo O objetivo deste estudo foi relatar o primeiro registro de Trichodina heterodentata em tuviras Gymnotus carapo. Um cultivo de tuviras no município de Jataí, estado de Goiás, na região Centro-Oeste do Brasil, apresentou taxas de mortalidade de peixes de 3-4% por tanque. A análise macroscópica constatou que os peixes tinham lesões na pele e brânquias. Raspados do tegumento e brânquias foram confeccionadas e secas ao ar à temperatura ambiente e impregnadas com nitrato de prata para identificar as espécies de Trichodinidae causadoras das lesões. Os tricodinídeos foram identificados como T. heterodentata, e suas características foram comparadas com as de T. heterodentata registradas para outras espécies de peixes hospedeiros. Observou-se que a presença de T. heterodentata estava associada ao manejo inadequado dos peixes, baixa qualidade da água, altas taxas de densidade de estocagem e manejo nutricional inadequado.

Abstract The aim of this study was to report the first record of Trichodina heterodentata in banded knifefish Gymnotus carapo. Banded knifefish cultivated in the municipality of Jataí, state of Goiás, in the central western region of Brazil, experienced fish mortality rates of 3-4% per tank. Macroscopic analysis found that fish had lesions on their skin and gills. Smears of the integument and gills were confectioned and air-dried at room temperature and impregnated with silver nitrate to identify the Trichodinidae species causing the lesions. The trichodinid were identified as T. heterodentata, and their characteristics were compared to those from T. heterodentata recorded from other species of host fish. It was observed that the presence of T. heterodentata was associated with inadequate fish management, low water quality, high rates of stocking density, and inadequate nutritional management.

Resumo Este trabalho foi desenvolvido com o objetivo de avaliar os efeitos dos íons nitrato e amônio sobre o acúmulo de nutrientes e produção da abobrinha italiana (cv. Caserta) cultivada em sistema hidropônico sob estrese salino. O experimento foi conduzido em casa de vegetação utilizando o delineamento experimental em blocos casualizados, arranjados em esquema fatorial 2 x 5, com 4 repetições. Os tratamentos foram constituídos de duas formas de nitrogênio (nitrato - NO3- e amônio - NH4+) e cinco níveis de condutividade elétrica da água de irrigação (CEa) (0,5; 2,0; 3,5; 5,0 e 6,5 dS m-1). As análises dos resultados indicaram que suprimento de N exclusivamente em forma de NH4+ promove maiores danos na membrana foliar e redução no acúmulo de macronutrientes e maiores relações Na+/K+, Na+/Ca++ e Na+/Mg++ na parte aérea das plantas de abobrinha. A irrigação com água a cima de 2,0 dS m-1 reduz o acúmulo de nutrientes na parte aérea das plantas e a produção de abobrinha. A toxicidade do NH4+ sob abobrinha italiana sobrepõe-se à toxicidade da salinidade, pois a fertilização exclusiva com esta forma de nitrogênio inibe sua produção, sendo a forma NO3- a mais adequada para o cultivo da espécie.

Abstract This research was carried out aiming at evaluating the effects of nitrate and ammonium ions on nutrient accumulation, biochemical components and yield of Italian zucchini (cv. Caserta) grown in a hydroponic system under salt stress conditions. The experiment was carried out in a greenhouse utilizing an experimental design in randomized blocks, arranged in a 2 x 5 factorial scheme, with 4 replications. The treatments consisted of two forms of nitrogen (nitrate - NO3- and ammonium - NH4+) and 5 electrical conductivity levels of irrigation water (ECw) (0.5, 2.0, 3.5, 5.0 and 6.5 dS m-1). The analysis of the results indicated that supply of N exclusively in NH4+ form promotes greater damage to the leaf membrane and reduction in accumulation of macronutrients and higher Na+/K+, Na+/Ca++ and Na+/Mg++ ratios in the shoots of zucchini plants. Electrical conductivity of irrigation water above 2.0 dS m-1 reduces the accumulation of nutrients in shoot and yield of Italian zucchini plant. The toxicity of NH4+ under Italian zucchini plants overlap the toxicity of the salinity, since its fertilization exclusively with this form of nitrogen inhibits its production, being the NO3- form the most suitable for the cultivation of the species.

RESUMO No semiárido do Nordeste brasileiro, a alta concentração de sais encontrada nas águas destaca-se como um fator limitante para agricultura irrigada. Assim, a adubação com nitrogênio (N), fosforo (P) e potássio (K) é uma estratégia capaz de amenizar o estresse salino sobre as plantas. Neste contexto, objetivou-se com esta pesquisa avaliar os teores de pigmentos cloroplastídicos, a fluorescência da clorofila, o dano na membrana celular e a produção de pinha irrigadas com água de diferentes condutividades elétricas e adubadas com nitrogênio, fósforo e potássio. Os tratamentos foram distribuidos em blocos ao acaso, em esquema fatorial 2 x 8, com três repetições, sendo dois níveis de condutividade elétrica da água de irrigação - CEa (0,8 e 3,0 dS m-1) e oito combinações de adubação NPK (100-100-100; 100-100-125; 100-125-100; 100-125-125; 125-100-100; 125-100-125; 125-125-100 e 125-125-125% das doses recomemdadas de N-P2O5-K2O). A CEa de 3,0 dS m-1 diminuiu os teores de clorofila a e total, o número de frutos por planta, e eficiência fotoquímica, e aumentou os teores de carotenoides e o dano na membrana celular de pinha. A adubação com 100-125-125; 125-125-100 e 125-125-125% das dose recomendada de N-P2O5-K2O resultou em maior dano na membrana celular de pinha.

HIGHLIGHTS Electrical conductivity of water of 3.0 dS m-1 reduces the chlorophyll synthesis and production of custard-apple. NPK recommendation of 100-125-125, 125-125-100 and 125-125-125% cause more damage to the cell membrane. Reduction in the quantum efficiency of custard-apple under salt stress is indicative of photoinhi-bitory damage.