ABSTRACT The quality of seedlings is a determining factor to guarantee the greatest potential crop productivity. The aim of this study was to evaluate the quality of lettuce seedlings grown in floating system, in relation to cell volume and electrical conductivity of the nutrient solution. The experiment was carried out in a completely randomized design, in a 3 x 2 x 4 factorial scheme, with three replicates. Seedlings of three lettuce cultivars (Great Lakes 659, Elba and Creta) were produced in two types of trays (128 and 200 cells) and fertigated with nutrient solutions (four electrical conductivities of 1.0; 1.5; 2.0 and 2.5 dS/m). The variables evaluated were: height, number of leaves, length of the main root, stem diameter, leaf area, total dry mass and shoot dry mass/roots dry mass (MSPA/MSR) ratio. Great Lakes 659 showed more vigorous seedlings for most of the evaluated variables. The three cultivars produced higher quality seedlings when cultivated in trays with 128 cells, with the EC of the nutrient solution ranging from 1.8 to 2.0 dS/m. productivity system design scheme replicates Creta (12 20 cells four 1.0 10 1 0 1.5 15 5 2. 25 dSm dS/m . dS m dS/m) height leaves root diameter area massroots roots MSPA/MSR MSPAMSR MSPA MSR (MSPA/MSR ratio 65 12 18 8 1. (1 6 (

RESUMO A qualidade das mudas é fator determinante para garantir o maior potencial produtivo das culturas. Objetivou-se avaliar a qualidade das mudas de alface produzidas em sistema floating, em função do volume das células e da condutividade elétrica da solução nutritiva. O experimento foi realizado no delineamento inteiramente casualizado, em esquema fatorial 3 x 2 x 4, com três repetições. Foram produzidas mudas de três cultivares de alface (Great Lakes 659, Elba e Creta), em dois tipos de bandejas (128 e 200 células), e fertirrigadas com soluções nutritivas de quatro condutividades elétricas (1,0; 1,5; 2,0 e 2,5 dS/m). As mudas foram avaliadas quanto a altura, número de folhas, comprimento da raiz principal, diâmetro de coleto, área foliar, massa seca total e razão entre massa seca de parte aérea e massa seca de raízes (MSPA/MSR). A cultivar Great Lakes 659 apresentou mudas mais vigorosas para a maioria das variáveis analisadas. As três cultivares produziram mudas mais vigorosas quando cultivadas em bandejas de 128 células, com solução nutritiva com CE variando entre 1,8 e 2,0 dS/m. culturas Objetivouse Objetivou se floating casualizado 4 repetições Creta, Creta , Creta) (12 20 células) 1,0 10 1 0 (1,0 1,5 15 5 2, 25 dSm dS/m . dS m dS/m) altura folhas principal coleto foliar MSPA/MSR. MSPAMSR MSPA/MSR MSPA MSR (MSPA/MSR) 65 analisadas 12 18 8 1, (1 (1, (MSPA/MSR 6 (

ABSTRACT Melon cultivation under saline conditions is a challenge, as the plants can suffer a reduction in fruit production and quality. The aim of this study was to evaluate the production and quality of noble melon fruit fertigated with different saline solutions and K/Ca ratios. The experimental design was of randomised blocks, with treatments arranged in a 3 x 6 factorial scheme, using three melon cultivars (Bazuca, McLaren, County) fertigated with six nutrient solutions [S1 - standard nutrient solution (SNS); S2 - SNS + NaCl (5.0 dS m-1); S3 - S2 enriched with K (50%); S4 - S2 enriched with K (100%); S5 - S2 enriched with Ca (50%); S6 - S2 enriched with Ca (100%)]. At the end of each cultivar cycle, the fruit was harvested and assessed for the following parameters: fresh fruit weight, fruit diameter, internal cavity, pulp thickness, pulp firmness, soluble solids content, titratable acidity, soluble solids/titratable acidity ratio, and vitamin C. Salt stress impaired the physical characteristics of the fruit of the three noble melon cultivars. The nutrient solution enriched with 50% K (S3) did not reduce the effect of salt stress on fresh weight or fruit size in the melon, but afforded an increase in fruit quality. challenge KCa ratios blocks scheme Bazuca, Bazuca (Bazuca McLaren County S1 S [S (SNS) 5.0 50 5 0 (5. m1 m 1 m-1) (50%) 100% 100 (100%) 100%. . (100%)] cycle parameters diameter cavity thickness firmness content solidstitratable ratio C (S3 (SNS 5. (5 m-1 (50% 10 (100% (S ( m- (50 (100 (10 (1

Abstract INTRODUCTION: Human visceral leishmaniasis is considered a major public health problem in the municipality of Cametá, Pará, Brazil. METHODS: This ecological study was conducted using data obtained from official Brazilian agencies. Spatial analysis of the variables was performed using the kernel interpolation technique and the bivariate Global Moran’s Index. RESULTS: The spatial distribution of the disease was not homogeneous, and it was associated with socio-environmental risk factors and public policies. CONCLUSIONS: Different relationships were observed between the variables studied and disease occurrence.

ABSTRACT Seed germination and seedling growth are the stages most sensitive to salt stress, which can induce ion-specific effects and oxidative stress. Although silicon (Si) has been known to improve plant defense systems against stressful-conditions, little is known about seed priming with Si and mechanisms of Si-mediated alleviation of salt stress in seedlings. To further the modulation of salt-stress responses and their relation with Si, seed priming with calcium silicate (0, 0.05 and 0.1 mM Ca2SiO4) was used in lettuce seeds to improve seedgermination and tolerance on subsequent salt-stress exposure (0 and 50 mM NaCl). The effect of Si-priming was assessed on germination, germination rate index and mean germination time and survival of seedlings in salt-stressful conditions supported by biochemical approach involving antioxidant responses. Overall results indicated that Si plays a role in alleviating the negative effects of salt stress by improving germination performance and displayed increased SOD, CAT and GR activities and reduced malondialdehyde and H2O2 contents. Thus, our findings demonstrate that seed-priming with Si is an efficient management technique thatcan be used to alleviate deleterious effects of salt-stressful on germination of lettuce seeds and enhance salt tolerance of seedlings due the increased activity of ROS- scavenging enzymes.

RESUMO O potencial fisiológico das sementes é um dos principais fatores que devem ser considerados no momento da implantação de uma cultura. Com isso, objetivou-se avaliar a aplicação exógena de bioestimulante em abobrinha, cv. Caserta Italiana, em condições de estresse salino. Para isso, o experimento foi dividido em duas partes, a primeira foi realizada em laboratório, utilizando o delineamento experimental inteiramente casualizado, em esquema fatorial 5 x 3 (dosagens de bioestimulante e tempos de embebição das sementes), com quatro repetições de 25 sementes. A segunda parte, foi realizado em casa de vegetação, em delineamento experimental inteiramente casualizado, no esquema fatorial 2 x 6, com quatro repetições, sendo dois níveis de salinidade da água de irrigação (0,5 e 5,0 dS m-1) e seis formas de aplicação do bioestimulante via sementes e folhas. O tratamento de sementes de abobrinha, cv. Caserta Italiana, com bioestimulante (Stimulate®) na dosagem de 10 mL L-1, durante 8 horas, mostrou-se viável e resultou em mudas vigorosas quando irrigadas com água salina de 5,0 dS m-1.

ABSTRACT The physiological potential of seeds is one of the main factors that should be considered at the planting of a crop. This study aimed to evaluate the exogenous application of biostimulant in zucchini, cv. Caserta Italiana, under salt stress conditions. For this, the experiment was divided into two parts. The first one was carried out in the laboratory, using a completely randomized experimental design, in a 5 x 3 factorial scheme (biostimulant doses and seed soaking times), with four replicates of 25 seeds. The second one was carried out in a greenhouse, in a completely randomized experimental design, in a 2 x 6 factorial scheme with four replicates, corresponding to two levels of irrigation water salinity (0.5 and 5.0 dS m-1) and six forms of biostimulant application in seeds and leaves. Treatment of zucchini seeds, cv. Caserta Italiana, with biostimulant (Stimulate®) at the dose of 10 mL L-1, for 8 hours, proved to be viable and resulted in vigorous seedlings when irrigated with 5.0 dS m-1 saline water.

ABSTRACT. Bell peppers are sensitive to salinity; therefore, it is necessary to find alternatives to reduce saline stress. An experiment was conducted in a greenhouse at Federal Rural University of the Semi-Arid Region, in Mossoró, Rio Grande do Norte State, Brazil, to evaluate the effects of salinity and K+/Ca2+ ratios on bell pepper production. The experimental design consisted of randomized blocks in a 5 x 4 factorial scheme with four replicates, corresponding to five K+/Ca2+ ratios (F1 = 3.3/1, F2 = 2.8/1, F3 = 2.2/1, F4 = 1.8/1, and F5 = 1.5/1) and four salinity levels in the nutrient solution using NaCl (1.75, 3.25, 4.75, and 6.25 dS m-1). The following parameters were evaluated: the number of fruits (total, marketable and unmarketable), the mean weight of fruits (marketable and unmarketable), fruit production (total, marketable and percentage of marketable fruits) and a salinity tolerance index. Generally, nutrient solution enrichment with K+ or Ca2+ did not cause significant increments in bell pepper yield. The fertigation treatments F2, F3, and F5 led to a higher bell pepper tolerance to salinity, allowing waters with higher salt concentrations to be used without causing a reduction in the yield.

ABSTRACT The state of Pará ranks second in Brazilian mineral production, where bauxite accounts for 84% of total mineral extraction, with negative impacts on the environment as a result. The determination of objectives and targets using environmental indicators as a tool to evaluate forest restoration processes is essential in the recovery of these exploited areas. This study aimed at evaluating the efficiency of forest restoration techniques by means of 13 qualitative and quantitative indicators for monitoring post-bauxite mining operations. Permanent plots were implanted in revegetated areas with the use of two techniques: planting of seedlings and stewarding of natural regeneration. It is concluded that the techniques are efficient for the recovery of forested area. However, natural regeneration showed greater efficiency for restoration for Density, Erosion and Exotic Species indicators. Still, natural regeneration should not be the sole option in the processes of ecosystem restoration, since planting proved to be more efficient for some indicators.

RESUMO A qualidade de mudas de espécies arbóreas é de fundamental importância para se obter êxito em projeto de reflorestamento ou de exploração comercial. Este trabalho foi desenvolvido com o objetivo de avaliar a influência de dois ambientes (AMB-1, casa de vegetação; AMB-2, câmara plástica instalada dentro da casa de vegetação) e concentrações de nutrientes aplicados via fertirrigação (0, 50, 100 e 150% de uma solução nutritiva padrão) na produção de mudas de Tabebuia aurea, utilizando delineamento inteiramente casualizado, com quatro repetições. Foram avaliadas as seguintes características: altura (H), diâmetro do coleto (DC), número de folhas (NF), área foliar (AF), massa seca da parte aérea (MSPA), massa seca de raiz (MSR) e massa seca total (MST), relação H/DC, área foliar específica (AFE), razão de área foliar (ARF) e índice de qualidade de Dickson (IQD). A análise dos dados revelou que houve interação significativa entre os fatores para a maioria das variáveis. O uso da câmara plástica (AMB-2) proporcionou maior crescimento das mudas de Tabebuia aurea. Soluções de fertirrigação com concentração de nutrientes variando de 80 a 100% da solução padrão proporcionam mudas de Tabebuia aurea de melhor qualidade.

ABSTRACT The quality of seedlings of tree species is crucial to succeed in reforestation project or commercial exploitation. This work was to evaluate the influence of two environments (AMB-1, greenhouse; AMB-2, plastic camera installed inside the greenhouse) and concentrations of nutrients applied by fertigation (0; 50; 100 and 150% of a patterns nutrient solution) in the production of seedlings of Tabebuia aurea using design was completely randomized, with four replications. The following growth characteristics were evaluated: height, stem diameter, number of leaves, leaf area, dry matter aerial part, dry root matter, dry root weight, total dry matter, height/stem diameter ratio, specific leaf area, leaf area ratio and Dickson quality index (IQD). Data analysis revealed that there was significant interaction between the factors for most variables. The use of the plastic chamber (AMB-2) provided greater growth of Tabebuia aurea seedlings. Fertigation solutions with nutrient concentrations varying from 80 to 100% of the standard solution provide better quality Tabebuia aurea seedlings.

RESUMO. Objetivou-se avaliar o efeito da aplicação do bioestimulante em sementes de maxixeiro, cultivar Liso de Calcutá, em condições de estresse salino. Utilizou-se o delineamento experimental em parcelas subdivididas, a parcela principal representada por dois níveis de salinidade da água de irrigação (0,5 e 3,5 dS m-1) e a subparcela composta por cinco doses de bioestimulante aplicados via tratamento de sementes (0, 5, 10, 15 e 20 mL kg-1), em cinco repetições. Avaliaram-se as seguintes variáveis: número de folhas, número de ramos, comprimento do maior ramo, massa seca de folhas, caule, frutos e total, número de frutos, massa média de frutos e produção de frutos. A salinidade da água de irrigação reduziu todas as variáveis analisadas, independente da dose de bioestimulante; o uso de bioestimulante, na ausência do estresse salino, proporcionou aumento do número de folhas, ramos, comprimento do maior ramo e do acúmulo de biomassa. O bioestimulante não é eficiente para reduzir o efeito da salinidade sobre a produção de maxixeiro, mas aumentou a produção de frutos, independente da salinidade.

ABSTRACT. The objective of this study was to evaluate the effects of a biostimulant on gherkin seeds, cultivar Liso de Calcutá, under conditions of salt stress. A split-plot experimental design with five replications was used; the main plot was represented by two levels of irrigation water salinity (0.5 and 3.5 dS m-1), and the subplot was composed of five biostimulant doses applied as a seed treatment (0, 5, 10, 15, and 20 mL kg-1). The following variables were evaluated: the number of leaves; number of branches; length of the largest branch; leaf, stem, fruit and total dry matter; number of fruits; average fruit weight; and fruit production. The values of all analyzed variables decreased with an increase in irrigation water salinity regardless of the biostimulant dose, but in the absence of salt stress, biostimulant use led to an increase in the number of leaves and branches, the length of the largest branch and biomass accumulation. Biostimulation was not effective in reducing the effects of salinity on gherkin production, but it increased fruit production regardless of the salinity level.

ABSTRACT Improvement of fallow vegetation can have a positive impact on the productivity of slash-and-mulch systems in eastern Amazonia. Phosphorus fertilization can increase biomass and nutrient stocks in the fallow phase, thereby improving nutrient cycling and crop productivity. Here, we compared biomass and nutrient stocks under three fallow management strategies: (1) natural fallow (regrowth vegetation) - NF; (2) NF vegetation improved with leguminous trees (Sclerolobium paniculatum Vogel and Inga edulis Mart.) - IF; and (3) NF vegetation improved with leguminous trees plus phosphorus fertilization - IF+P. We quantified above- and belowground biomass and N, P, K, Ca, and Mg stocks after 23 months of fallow. The IF+P increased aboveground (leaf + branch + stem + liana) biomass and N, P, Ca, and Mg stocks, compared to NF. Similarly, total (aboveground + belowground) biomass and N and P stocks were higher for IF+P than for NF. The differences in aboveground biomass between NF and improved fallow managements were attributed exclusively to the contribution of the tree species enriching fallow vegetation. Phosphorus application increased the aboveground biomass accumulation of the species for fallow improvement. Improving the fallow vegetation with P-fertilized, fast-growing, N-fixing species represents an efficient management strategy to accelerate the reestablishment of biomass and nutrient stocks in slash-and-mulch systems in Amazonia.

RESUMO A qualidade das mudas é fator primordial para se obter êxito na produção de hortaliças. Este trabalho foi desenvolvido com o objetivo de avaliar a produção, em substrato de fibra de coco, de mudas de cultivares de maxixeiro, fertirrigadas com diferentes concentrações de nutrientes. O delineamento utilizado foi o inteiramente casualizado, em esquema fatorial 3 x 5, com quatro repetições. Os tratamentos resultaram da combinação de três cultivares de maxixe (Do Norte, Liso de Calcutá e Liso Gibão) com cinco concentrações de nutrientes na solução (0, 25, 50, 75 e 100%). A solução nutritiva, considerada padrão, corresponde à recomendada para a cultura do meloeiro em sistema hidropônico. Foram avaliadas as variáveis: índice de clorofila, comprimento da parte aérea, número de folhas, diâmetro do colo, comprimento da raiz principal, massas das matérias secas das folhas, das raízes, do caule e total, área foliar, área foliar específica e razão de área foliar. Todas as variáveis foram afetadas pela concentração de nutrientes na solução nutritiva. Os cultivares Liso de Calcutá e Liso Gibão apresentaram mudas mais vigorosas. O uso de fibra de coco na produção de mudas de maxixeiro é mais eficiente com as soluções nutritivas em concentrações variando de 75 a 100% da solução recomendada para o cultivo do meloeiro.

ABSTRACT Seedling quality is a key factor to achieve success in vegetable production. The present work aimed to evaluate the production of gherkin seedlings in substrate of coconut fiber fertirrigated with different concentrations of nutrients. The experimental design was completely randomized in a 3 × 5 factorial with four replications. The treatments consisted of combinations of three cultivars of gherkin (Do Norte, Liso de Calcutá, e Liso Gibão) with five concentrations of nutrients in the solution (0, 25, 50, 75, and 100%). The nutrient solution, considered standard, matches the recommended solution for melon in hydroponic systems. We evaluated the variables: chlorophyll index, shoot length, number of leaves, stem diameter, main root length, dry weight of leaves, roots, and stem, mass of total dry matter, leaf area, specific leaf area, and leaf area ratio. All variables were affected by the ionic concentration in nutrient solutions. The use of coconut fiber in the production of gherkin seedlings is more efficient with nutrient solutions in concentrations ranging from 75 to 100% of the recommended solution for melon cultivation.

RESUMO A vegetação de pousio é um dos principais componentes dos sistemas agroflorestais sequenciais de derrubada e queima, praticados tradicionalmente pela agricultura familiar na Amazônia. A remoção progressiva de nutrientes do solo por essa prática implica reduções contínuas nos estoques de carbono e nutrientes causando declínio da produtividade do solo, perda da capacidade de regeneração e diminuição da diversidade de espécies da vegetação. O melhoramento de pousio com espécies leguminosas fixadoras do nitrogênio atmosférico pode contribuir para uma maior produção de biomassa e acúmulo de nutrientes em comparação com a vegetação espontânea, atendendo à demanda nutricional das culturas subsequentes, podendo ser considerada como uma tecnologia de produção sustentável. Esse trabalho avaliou o efeito da adubação fosfatada de baixa solubilidade no acúmulo de biomassa e nutrientes da parte aérea de leguminosas arbóreas utilizadas em melhoramento de vegetação de pousio. O experimento foi conduzido por 23 meses, em um sistema agroflorestal de "corte e trituração" em Marapanim, Pará. Foram utilizadas as espécies tachi-branco - Sclerolobium paniculatum Vogel e ingá - Inga edulis Mart e foram estimados biomassa, teor e estoque de nutrientes dos compartimentos folha, galho e tronco. Houve acúmulo de biomassa, estoques de P, Ca e Mg nas folhas, estoque de P nos galhos e o teor de cálcio nas folhas das leguminosas é limitado por fósforo, segundo os resultados encontrados. A espécie Inga edulis apresentou maiores teores de potássio, cálcio e magnésio nos compartimentos folha, galho e tronco, enquanto que a espécie Sclerolobium paniculatum apresentou maiores acúmulos de biomassa e estoques de nitrogênio, fósforo, potássio, cálcio e magnésio nos compartimentos folha, galho e tronco.

ABSTRACT The fallow vegetation is the main component of sequential agroforestry systems in Amazon rain forest.The progressive removal of soil nutrient by slash/mulch agriculture involves continuing losses in carbon and nutrient stocks, leading to decline in soil productivity, low regeneration ability and decrease of species diversity of fallow vegetation. The fallow vegetation management by introducing fast growing leguminous trees has the potential to accumulate more biomass and nutrients to serve the nutrient demands of crops and its management has been considered as a sustainable technology production. This study aimed to evaluate the effect of low solubility of phosphorus fertilizer in the biomass and nutrient stocks of leguminous trees used in fallow improvement. The experiment was conducted for 23 months in a sequential agroforestry slash-and-mulch system in eastern Amazon forest. The species selected were tachi-branco - Sclerolobium paniculatum Vogel and inga - Inga edulis Mart. Biomass and nutrient stocks and nutrient concentrations of leaf, branch and trunk were estimated. Phosphorus fertilization had a positive effect on calcium concentration in the leaves and stocks of biomass and nutrient contents (phosphorus, calcium and magnesium) in the leaves of legume trees. Inga edulis showed higher levels of potassium, calcium and magnesium concentrations in leaves, while Sclerolobium paniculatuttm showed higher biomass and stocks of nitrogen, phosphorus, potassium, calcium and magnesium in leaf, branch and trunk.

Resumo: A qualidade fisiológica de sementes utilizada na produção agrícola é um dos principais fatores que deve ser considerado no momento da implantação da cultura. Objetivou-se avaliar a qualidade de sementes de maxixeiro, cv. Liso de Calcutá, provenientes de plantas oriundas de sementes previamente tratadas com bioestimulante (0, 5, 10, 15 e 20 mL. kg-1 de sementes) e cultivadas sob dois níveis de salinidade da água de irrigação (0,5 e 3,5 dS. m-1). Inicialmente, determinou-se o teor de água das sementes e realizou-se os testes de germinação, envelhecimento acelerado, emergência em casa de vegetação, índice de velocidade de emergência, altura e massa seca da parte aérea das plântulas. Constatou-se que a qualidade fisiológica de sementes de maxixeiro oriundas de plantas submetidas ao estresse salino é afetada de maneira negativa, e que o uso de bioestimulante, aplicado via semente, proporciona efeito benéfico na qualidade fisiológica das sementes produzidas na geração seguinte.

Abstract: The physiological quality of seeds used in agricultural production is one of the main factors that should be considered when implanting the culture. This study aimed at evaluating the quality of bur gherkin seeds, cv. Liso de Calcutá, coming from plants grown from seeds that were previously treated with biostimulant (0, 5, 10, 15 and 20 mL. kg-1 seeds) and cultivated in two irrigation water salinities (0.5 and 3.5 dS. m-1). Initially, the water content of seeds was determined and the following tests were performed: germination, accelerated aging, greenhouse emergence, emergence speed index, height and dry mass of seedling aerial part. It was found that the physiological quality of bur gherkin seeds coming from plants that were subjected to salt stress is negatively affected, and that the use of biostimulant, applied via seeds, provides beneficial effects on the physiological quality of seeds produced in the next generation.

Resumo O trabalho objetivou mapear a cobertura e uso do solo na área da bacia hidrográfica do rio Peixe-Boi, nordeste paraense, identificar conflitos de uso nas áreas de preservação permanente e investigar a relação deles com a qualidade da água. Utilizou-se imagem do sensor LISS-3 do satélite Resourcesat com resolução espacial de 23,5 m para classificação supervisionada e obtenção de classes de uso e cobertura da terra com base em 22 amostras de treinamento. Para se determinar a qualidade da água foram coletados 28 pontos amostrais nas redes de drenagem. A relação entre antropização e qualidade da água foi analisada a partir das observações das mudanças de uso da terra, por meio de imagens de satélite e coletas in loco das amostras de água. Os resultados obtidos revelam que 46% das APPs encontra-se em conflito de uso, sobretudo pela ocupação indevida das classes área urbana, solo exposto e especialmente pastagem com mais de 84% da área em conflito de uso. Em alguns pontos amostrais, foram observados níveis críticos de oxigênio dissolvido chegando a 2,14 mg L-1 e pH de 5,12, valores abaixo do estabelecido pela resolução 357/05 do CONAMA para água doce. Constatou-se que as piores condições de qualidade da água podem estar relacionadas às áreas de uso e ocupação irregulares dentro das APPs. Diante do exposto, verifica-se a necessidade, emergencial, de planejamento do uso e ocupação das terras na área da bacia hidrográfica do rio Peixe-Boi para a recuperação ambiental e da qualidade da água.

Abstract This study mapped the land use and land cover of the catchment area of the Peixe-Boi River watershed, in northeast Pará, in order to identify conflicts of land use in the permanent preservation areas, and to relate them to water quality. We used LISS-3 sensor imagery from the Resourcesat satellite with a spatial resolution of 23.5 m for supervised classification of land use and land cover based on 22 training samples. Water quality was determined based on 28 sampling points in drainage network. The relationship between human disturbance and water quality was analyzed based on observations of land use changes using satellite imagery and in situ collection of water samples. The results show that 46% of the permanent preservation areas have conflicted uses, especially with respect to urban squatters, exposed soil and, most notably, pasture, with over 84 % of the area in conflict. Critical levels of dissolved oxygen reaching 2.14 mg L-1 and pH of 5.12 were observed in some sampling points. These values are below the fresh water standards set by Resolution 357/05 of CONAMA. The poorest water quality may be related to irregular use and occupation of areas within the permanent preservation areas. There is therefore an urgent need to develop a plan for the sustainable use and occupation of catchment area land in the Peixe-Boi River watershed in order to restore the environment and improve water quality.

RESUMO O uso de bioestimulantes tem se difundido na agricultura brasileira, promovendo o crescimento e aumento na produtividade das culturas, mas ainda são incipientes estudos sobre o uso destas substâncias em plantas sob estresse, principalmente sobre estresse salino. Objetivou-se avaliar o uso de bioestimulante como agente amenizador do estresse salino na cultura do milho pipoca. O experimento foi conduzido em ambiente protegido no Campus da Universidade Federal Rural do Semi-Árido, em Mossoró-RN. Utilizou-se o delineamento experimental inteiramente casualizado, com os tratamentos distribuídos em esquema fatorial 2 x 4, referentes a dois níveis de salinidade da água de irrigação (0,5 e 4,5 dS m-1) e quatro doses de bioestimulante aplicado via tratamento de sementes (0; 5; 10 e 20 mL kg-1 de sementes), com cinco repetições. Utilizou-se o bioestimulante comercial Stimulate® (0,009% citocinina, 0,005% giberelina e 0,005% de auxina) e as plantas foram coletadas aos 50 dias após a semeadura. Foram avaliadas as seguintes variáveis: altura de plantas, diâmetro do colmo, número de folhas, área foliar, massa seca de colmo, massa seca de folhas, massa seca de raiz, massa seca de pendão, massa seca total e área foliar específica. O uso de água salina na irrigação provocou redução na maioria das variáveis de crescimento do milho doce, independentemente do tratamento de sementes com bioestimulante. O tratamento de sementes com Stimulate® promove o desenvolvimento de plantas de milho pipoca, mais não inibiu nem amenizou o efeito da salinidade sobre as plantas.

ABSTRACT The use of biostimulants has become widespread in Brazilian agriculture, promoting growth and increased crop yields. However, studies on the use of these substances in plants under stress are still being developed, especially for salt stress. The aim was to evaluate the use of bio-stimulants to relieve salt stress in popcorn. The experiment was carried out in a greenhouse on the campus of the Federal Rural University of the Semi-Arid in Mossoró, in the State of Rio Grande do Norte, Brazil. A completely randomised design was used, with treatments distributed in 2 x 4 factorial scheme, representing two levels of salinity of the irrigation water (0.5 and 4.5 dS m-1) and four levels of biostimulant, applied by seed treatment (0, 5, 10 and 20 ml kg-1seed), with five replications. The commercial biostimulant Stimulate® was used (0.009% cytokinin, 0.005% gibberellin and 0.005% auxin), with the plants being harvested 50 days after sowing. The following variables were evaluated: plant height, stem diameter, number of leaves, leaf area, stem dry weight, leaf dry weight, root dry weight, tassel dry weight, total dry weight and specific leaf area. The use of saline water for irrigation caused a reduction in most growth variables in the sweet corn, regardless of seed treatment with biostimulants. Seed treatment with Stimulate® promotes development in popcorn, but did not inhibit or lessen the effect of salinity on the plants.