Water stress negatively affects vegetables. It causes changes in the physiological and biochemical aspects of plants, leading to reduced productivity. Despite being resistant to low water availability, sorghum production is significantly reduced under these conditions. Therefore, it is necessary to evaluate the use of mitigators of this stress, such as Brassinosteroid (BR) and Salicylic Acid (SA). The objective of the work was to evaluate the effect of the isolated and combined application of brassinosteroids and salicylic acid on sorghum plants subjected to water stress. The study was implemented using a randomized block design (RBD), with a 2x4 factorial scheme, including two levels of water in the substrate (irrigated and water stress) and four ways of using bioregulators (Control - without the bioregulator; application of BR in concentration of 0.1 μM; application of SA at a concentration of 1 mM; and the combination of the two bioregulators (BR and SA), totaling eight treatments, five replications and 40 experimental units. Sowing was carried out with ten seeds per pot, with thinning carried out and maintaining two plants. The moisture of the substrate was maintained close to field capacity until 50 days after sowing (DAS), when the plants reached pre-flowering (the most sensitive phase), and were then subjected to water stress treatment with the gradual suspension of irrigation. From 51 to 56 DAS, the plants were subjected to moderate stress, with 50% of field capacity. From 57 to 62 DAS, severe stress began, with the substrate at 20% of field capacity. Plants in the control treatment remained irrigated close to field capacity until physiological maturation of the grains. Water stress and the application of bioregulators influenced growth variables. The BR+SA treatment proved to be more efficient, as it achieved a greater increase in stem height and diameter, in addition to greater leaf dry mass, stem dry mass, root dry mass and total seed weight. The joint application of bioregulators was also responsible for increasing the green index in leaves, the maximum quantum efficiency of photosystem II, the primary efficiency of photosystem II and the content of photosynthetic pigments compared to control treatments (without application of bioregulators).

The cowpea crop is important as a source of food, employment and income generation, in addition to stimulating the economy in the North and Northeast of Brazil. However, the low productivity of the crop is an obstacle to be overcome, through efficient technologies and management that increase production without generating excessive costs for farmers. The objective was to evaluate, through digital images of cowpea leaves, the indexes of plant color would be correlated with the nitrogenous status of the plants. Along with evaluation of vegetation indexes that correlate with the productivity of different cowpea genotypes. Twenty genotypes of cowpea were used in the experimental conduction, in order to determine an index that adapts to different genotypes of cowpea. The indexes that improved correlated with Leaf Nitrogen Content was the DGCI, which had a strong positive correlation of 0.7. As for productivity, it was not possible to determine a vegetation index capable of predicting productivity. This demonstrated that it is possible to reliably determine the leaf nitrogen of several genotypes of cowpea in reality, but it is not feasible to use these indexes for productivity.

The Amazon biome has been suffering recurrent degradation and great loss of its biodiversity, and there are still many studies that need to be done to learn more about its fauna and flora. Dragonflies are a small group of aquatic insects classified in the order Odonata, they are sensitive organisms to changes in habitat, so they are known as good indicators of environmental conditions, and are used in several ecological studies to measure impacts caused by anthropic activities that cause degradation of ecosystem resources and especially of aquatic resources. The first chapter of this work studies which mechanisms can influence the Odonata metacommunity in a landscape cover loss gradient. The study also aims to find out whether the factors of space and variation in the environment can influence the two suborders of Odonata (Anisoptera and Zygoptera). The second chapter evaluates the response of dragonfly diversity (abundance and richness) to environmental changes in streams located in the Legal Amazon of Maranhão, and in view of this assessment, identify which factors most influence the richness and abundance of the sampled species. This study was carried out in streams located in the Pindaré River basin in the legal Amazon of Maranhão in an environmental gradient that suffers from degradation and loss of biodiversity. Our results showed that Odonata species presented a distinction in distribution between the two suborders of the order in view of this environmental gradient and also due to the body characteristics of the species of each suborder. And we were also able to perceive differences in species richness and abundance when comparing the two suborders (Anisoptera and Zygoptera), showing that the abundance was lower in the species of the suborder Zygoptera due to their relationship with environments with greater vegetation cover. In view of our findings, monitoring and preservation of these environments are necessary to reduce the loss of aquatic biodiversity that inhabits them and especially of species that are restricted to environments with greater vegetation cover, since they are of great importance.

Fire in the Cerrado plays an important role in nutrient cycling and in maintaining the diversity and structure of habitats, but the increase in anthropic pressures has significantly altered its natural regimes, impacting the functioning of these ecosystems. The Campos Amazônicos National Park (PNCA) protects a significant part of the largest enclave of Cerrado in the south of the Amazon, areas that are frequently affected by fire and require a lot of effort for their proper management. As part of a broader proposal for monitoring the effects of fire in experimental burnings to be carried out in the PNCA, this project seeks to evaluate the responses of the herbaceous stratum in plant formations subjected to burnings in different periods within two experimental zones (Zones A and B). Each experimental zone has 15 plots of 40x40m where 6 plots will be burned at the beginning of the dry season (May); 6 plots between the middle and end of the dry season (August); and 3 excluded from fire. Before applying these treatments, more precisely in February 2019, a survey of 8 permanent plots of 1x1 m (randomly distributed) was carried out in each plot to then collect data on species richness, abundance and regeneration. In May 2021, two years after the pre-fire survey, data were collected again. Thus, the effects of fire on herbaceous vegetation were evaluated, since this is the stratum mainly affected by fire. It is the first research to report a set of experimental burnings in cerrado environments in the Amazon, within a context of integrated fire management, which made it possible to advance in understanding the similarities and differences in the relationships between fire and vegetation in the comparison with results obtained in other experiments conducted in core areas of the Brazilian Cerrado.

The Brazilian Cerrado is considered one of the world's biodiversity hotspots, conserving this landscape has become a major challenge for scientists and conservationists. In this biome, the variation in environmental conditions due to high rates of deforestation, fragmentation and intensification of land use can influence the distribution of species, which are associated with some environmental characteristics. Dung beetles (Coleoptera: Scarabaeinae) are insects sensitive to habitat disturbances and have been used to monitor environmental changes. The objective of this research was to study the diversity of the dung beetle communities (composition patterns, richness and abundance) in the face of landscape changes (gallery forests, forest fragments and pastures) in the Lajeado river basin region, Cerrado of the state of Maranhão. Sampling (through pitfall traps) was carried out in 30 areas located in the municipalities of São João do Paraíso, Porto Franco, Lajeado Novo, Campestre do Maranhão and Ribamar Fizene, Maranhão, Brazil. We collected 2,855 dung beetles belonging to 17 genera, 32 species and 30 morphospecies. The most abundant species were Canthon histrio (Le Peletier & Serville, 1828) (28.12%, n = 803), Onthophagus aff. rubrescens (Blanchard, 1846) (13.6%, n = 390) and Eurysternus caribaeus (Herbst, 1789) (5.11%, n = 146). The highest species richness and abundance were recorded in the forest fragment, followed by pasture, while the gallery forest had lower species richness, but similar abundance to pasture. Species composition was dissimilar between forest and pasture environments. The species Canthon aff. xanthopus (Blanchard, 1846) and Deltochilum enceladus (kolbe, 1893) were associated with forest fragments. Canthidium aff. barbacenicum (Preudhomme de Borre, 1886), Canthon octodentatus (Schmidt, 1920), Coprophanaeus magnoi (Arnaud, 2002), Dichotomius bos (Blanchard, 1846), Dichotomius nisus (Olivier, 1789) and Pseudocanthon xanthurus (Blanchard, 1846) had strong relationship with pastures. The species Eurysternus caribaeus (Herbst, 1789) was associated with forest fragments and gallery forests. Our results provide evidence that there are significant distributions and associations between beetle species and the environmental structure of the different phytophysiognomies of the Lajeado river basin. In view of this, we encourage environmental management to develop measures aimed at preserving areas in the study region that are currently suffering from anthropic processes, in order to minimize the impacts caused on scarab beetle communities.

With the growing need for more sustainable agricultural production and reduced dependence on pesticides, there is a need to improve biological control techniques and their effective application. Thus, the application of fungi in the endophytic form is a promising technique. Therefore, the present work aimed to select isolates of entomopathogenic fungi with high virulence against Spodoptera frugiperda, a key pest of corn, aiming to control this pest via endophytic colonization of plants with these fungi. Two Beauveria bassiana isolates (LPP 129 and LPP SP1) and two Metarhizium anisopliae isolates (ESALQ 818 and LPP M1) were tested for virulence against S. frugiperda larvae via contact. Corn plants were then inoculated with fungal conidia through foliar spray and the presence of the fungi in different plant tissues was evaluated 7, 14, 21, 28 and 90 days after inoculation. After confirmation of endophytic colonization in leaf tissues, corn leaves were offered to third instar S. frugiperda and survival was monitored over 10 days. Agronomic parameters related to plant growth were also evaluated. The results showed variability in virulence of the four isolates against S. frugiperda larvae, in which LPPM1 isolate was considered to have low virulence, LPP 129 median virulence and both ESALQ 818 and LPP SP1 were highly virulent, killing >90% of the larvae in 5-6 days. The two most virulent isolates were used for inoculation via foliar spraying in maize plants. Endophytic colonization of plants with ESALQ 818 and LPPSP1 were efficient in reducing the survival of S. frugiperda larvae that fed on leaves. The treatments differed significantly (P<0.0001) from the control group. Larvae exposed to corn leaves colonized with the fungi showed a mean survival of 3 days (S50), and 96% mortality on the 7th day of evaluation. The control group had a survival rate of approximately 90%. As for the agronomic parameters evaluated, significant increases were observed in the variables root length, stem diameter, plant height, leaf area and number of leaves. LPPSP1 and ESALQ 818 efficiently colonized maize plants via foliar inoculation, and was detected for up to 90 days after inoculation. Plants colonized with fungi in the endophytic form proved to be efficient and virulent against S. frugiperda larvae, as well as causing positive effects on plant growth, indicating the potential of endophytic colonization for biological control strategies.

In soils of the humid tropics, specifically in the north of Maranhão, soil organic matter (SOM) and the sum of basic cations such as calcium (Ca), magnesium (Mg) and potassium (K) are one of the main indicators of soil quality. soil to assess sustainability and viability in agroecosystems. Therefore, the objective of this work was to identify chemical indicators in the soil of the humid tropics that correlate with corn productivity and that can contribute to the ecological intensification of agriculture in the region. The experiment was carried out in the community of Santa Rita do Vale, in the municipality of Santa Rita, in the northern region of the state of Maranhão, Brazil. The experiment consisted of evaluating two areas with a size of 1,680 m2 each, 24 points were evaluated at each depth, 24 points (0-15 cm) and 24 points (15-30 cm). In order to evaluate the attributes Ca, Mg, K, P, MOS, COT, COP, COAM and ECOT, four soil samples were collected per point, each repetition with a distance of two meters to the central point, to form a sample. composed. Corn yield was sampled in a 4 m2 (2m x 2m) area around each sampling point. Corn yield showed positive correlations with the variables COAM, Ca, Mg, Ca+Mg and P, in both soil depths. Except for K, which showed a positive correlation with productivity only at 15-30 cm depth. The MOS and COAM variables showed a positive correlation with the cations (calcium and calcium+magnesium) in the 0-15 cm soil layer. In the 15-30 cm layer of soil, only the COAM showed a positive correlation with calcium and calcium+magnesium. Overall, at 0-15 cm depth of soil, productivity showed a positive correlation with the indicators, COAM, Mg, Ca+Mg, Ca and K and negatively correlated with COP. The mean ratio of COAM:clay at 0-15 cm depth was (1:8.56). At a depth of 15-30 cm the average COAM:clay ratio was (1:8.67). The chemical indicators that determine corn productivity are organic carbon associated with minerals, magnesium, calcium and calcium+magnesium, potassium and phosphorus. MOS and COAM showed interactions with calcium and calcium+magnesium. The COAM:clay ratio at 0-15 cm depth was 1:8.34 and at 15-30 cm depth it was 1:8.76, considering the soil of good structural quality. We determined that the critical value of calcium is 20 mmolc dm-3 and that of COAM is 15 g kg-1 for the depth of 0-15 cm and in the depth of 15-30 cm the critical value of calcium is 20 mmolc dm- 3 and COAM of 15 g kg^-1.

Adequate levels of nitrogen supplementation in Agrosilvopastoral systems can provide mutual gains between system components. The objective was to evaluate the soil attributes and chemical composition of Megathyrsus maximus cv. Massai in an agrosilvopastoral system. The experiment was established in 2017 in 3 ha with the planting of massai (Megathyrsus maximus Jacq. cv. Massai) in intercropping with corn (Zea mays L.) between double rows of thrush (Mimosa caesalpiniaefolia Benth), in the spacing of 30 × 3 × 2 m, and babassu (Atallea speciosa Mart.). The experimental design was randomized in blocks with three replications. Each block of 1 ha was subdivided into four paddocks of 0.25 ha, with an average of 35 babassu palm trees/ha and 276 sabiá trees/ha. The treatments were 0, 100, 200 and 400 kg ha-1 year-1 of nitrogen (N), the fertilizations were with urea. Ring steers were used, with initial average body weight (BW) of 200 ± 35 kg, according to the put-and-take technique, with two test animals per paddock, and adjustment animals according to forage availability [2 kg green matter (MVS) kg PC-1]. Two soil collections were carried out (Aug/2020 and July/2021). The evaluation of soil attributes was carried out at five distances (0; 3.5; 7.0; 10.5 and 14 m) perpendicular to the double rows of thrush. Mini trenches (30 x 30 x 30 cm) were opened to collect undisturbed samples at depths of 0 ±10, 10 ±20, 20 ±30 cm, and density, macroporosity, microporosity and total porosity were analyzed. Deformed samples at the same depths perpendicular to the mini-trenches were collected for soil chemical analysis (P, K+, Mg+2 and Ca+2). The masai was evaluated from Jun/2021 to Feb/2022 every 28 days, and the total forage mass (MFT), percentage of green (%FV) and senescent (%FS), forage height and density (DF), green forage crude protein (PBFV) and senescent (PBFS), green forage mineral matter (MMFV) and senescent (MMFS); neutral detergent fiber from green (FDNFV) and senescent (FDNFS) forage; green (FDAFV) and senescent (FDAFS) forage acid detergent fiber, green (LIGFV) and senescent (LIGFS) forage (LIGFS) lignin. The SAS Proc Mixed program was used and the means of each treatment were compared using Tukey's test, at a 5% probability level. The distance from the tree component did not significantly influence (P<0.05) the physical attributes of the soil, however, there was a difference (P<0.05) for microporosity, treatments 0 and 100 Kg N ha-1 year- 1 showed values 11.2% higher than the other treatments. For the chemical attributes of the soil, there was no difference (P<0.05) between the treatments, since the depths differed, the superficial layer (0-10 cm), were 31%, 8.82% and 23.53% of P, Ca2+ and k+ respectively higher than the other evaluated layers. The year 2020 showed lower concentrations of P, Mg+2 and K+ in the interaction of fertilization and distances. Forage mass was not influenced by fertilization levels (variation from 2128.21 Kg N ha-1 year-1 to 2203.03 Kg N ha-1 year -1. Lower percentage of green forage (51.50%) and higher senescent (48.89%) was observed in the treatment without fertilization. The percentages of MM, PB, NDF and LIG were not influenced by fertilization. January 2022 showed a higher value of MM (17.54% more), LIG was also higher in this month (31.07% more, together with the months of August and October 2022. The lowest value of PB was in July 2021 (24.43% lower). FDN was higher in August 2021 and February 2022 (15% and 12.15% higher respectively. The agrosivilpastoral systems under nitrogen fertilization, improves the physical and chemical conditions of the soil, providing the formation of macroaggregates. The chemical attributes, on the other hand, present relevant results, but require more time to be observed. Nitrogen fertilization had a positive influence on the production of MSV in agrosivilpastoral systems, as well as on the crude protein content of the forage, with treatments with higher protein applications having higher concentrations in the forage.

There are several methodologies available to analyze the GxE interaction and the choice will depend of several factors. The GGE Biplot and REML/BLUP methods have been used together to investigate the interaction in several annual crops, however there are no reports for sorghum. In view of this, the objective is to evaluate the adaptability and stability of sorghum genotypes aiming at biomass production in the cerrado of southern Maranhão by the REML/BLUP method and GGE biplot. The trials were conducted in Balsas - MA in the second harvest of 2021 and 2022, arranged in DBC with three replications and ten treatments, with the following cultivars: Sudão, AGRI 001-E, AGRI 002-E, BRS 658, BRS 810, BRS Ponta Negra, BRS 373, BR 509, BR 506 e IPA 467-4-2. The production of green matter and dry matter in t ha-1 were evaluated. Model significance was estimated by deviance analysis. The estimates of variance components were determined by the REML (Restricted Maximum Likelihood) procedure and adaptability and stability of genotypes were determined by the BLUP (Best Linear Unbiased Prediction) procedure under harmonic means and by biplot GGE techniques. For analysis under harmonic means, the SELEGEN REML/BLUP program was used. For the GGE biplot analysis, the R statistical software was used. Through the simultaneous evaluation of productivity, stability and adaptability (MHPRVG), the genotypes BRS Ponta Negra, AGRI 002-E, BRS 506 and BRS 509 remained among the first positions in the ranking, demonstrating increased adaptability, stability and productivity. Through the GGE biplot it was possible to identify four genotypes with performance above the average of the environments, namely G6 (BRS Ponta Negra), G9 (BRS 506), G3 (AGRI 002-E) and G2 (AGRI 001-E), however, G9 and G2 had high instability. Thus, for the environmental conditions of Balsas-MA and considering both methodologies under study, the BRS Ponta Negra cultivar proved to be the cultivar with the greatest potential for recommendation, followed by the AGRI 002-E and BRS 506 cultivars

The presence of leguminous trees with the potential for biological nitrogen fixation can increase forage production and reduce dependence on chemical inputs in agrosilvopastoral systems. The objective was to quantify the biomass and nutrients of Massai and Sabiá grass and estimate the natural abundance of δ13C and δ15N via leguminous trees under different levels of nitrogen fertilization in an agrosilvopastoral system, in the humid tropics of Maranhão. The experiment was carried out at the Technological Reference Unit (URT) in Lavoura Pecuária Floresta Integration (ILPF) of the Brazilian Agricultural Research Corporation (EMBRAPA), Cocais unit, in the municipality of Pindaré Mirim - MA, Brazil. The experiment was established in 2017 on 3 ha with the planting of massai (Megathyrsus maximus cv. Massai) intercropped with corn (Zea mays L.) between double rows of sabiá (Mimosa caesalpiniaefolia Benth) at a spacing of 30 x 3 x 2 m. The experimental design was randomized in blocks with three replications. Each 1 ha block was subdivided into four 0.25 ha paddocks. The treatments were 0, 100, 200 and 400 kg/ha/year of N. Fertilizations were carried out with urea, in the rainy season. Nelore steers were used, with an average initial weight of 200 ± 35 kg, adopting the continuous grazing method with variable stocking rate, according to the put-and-take technique. adjustments according to forage availability. In the trees, the dendrometric variables (plant stand, stem length (CF), diameter at the base (DB), diameter at breast height (DBH), Lorey height (hL) and Volume), total aerial biomass (leaves and branches), basic density at the base (0.5 m) and at breast height (1.3 m), chemical composition (dry matter (DM), mineral matter (MM), organic matter (OM), crude protein ( CP), nitrogen (N), carbon (C), C:N ratio, neutral detergent fiber (NDF), acid detergent fiber (ADF) and Natural abundance of δ13C and δ15N, and derived nitrogen of air (Ndda). Animal performance was evaluated through stocking rate (TL), average daily gain (ADG), average gain per area (GPA) and forage through total forage mass (MFT), percentage of green forage (%FV). ) and senescent (%FS), forage density (DF), green forage crude protein (PBFV) and senescent (PBFS) and green forage mineral matter (MMFV) and senescent (MMFS). The SAS Proc Mixed program was used and the means of each treatment were compared using the Tukey test, at a 5% probability level. There was no significant difference (P>0.05) between the levels of fertilization for the dendrometric variables, total area biomass, basic density, chemical composition and δ13C, but there was a difference (P<0.05) between the evaluation periods. The stand reduced from 180 to 165 plants/ha, between the first and second evaluations, respectively. The CF (5 to 7 m); DB (8 to 9 cm); DAP (6 to 7 cm); hL (5 to 7 m); volume (0.5 to 0.9 m3); biomass in the leaf fraction (23 to 206 kg.ha-1); biomass in branches with circumference <4.9 cm (675 to 996 kg.ha-1); with circumference 5-10 cm (696 to 1164 kg) and circumference >10 cm (increase from 2014 to 3716 kg) were higher in the second evaluation. The basic density at the base and at breast height varied from 0.7 and 0.5 g/cm³, in the first evaluation, to 0.79 and 0.72 (g/cm³, in the second evaluation. In the chemical composition of the leaves, the MM, N and CP concentrations were higher in the second evaluation period with 108, 26 and 165 g kg-1, compared to the first (65, 19 and 129 g kg-1 respectively). was higher in the first evaluation compared to the second (13).In the branch fraction < 4.9 cm, the DM, MM and C:N contents were higher in the first evaluation with 46.47, 492.0 and 74 g kg-1 , in relation to the second (36, 27 g kg-1 and 56), while OM and N (973 and 8 g kg-1 respectively) were higher in the second evaluation compared to the first (952 and 6 g kg-1 respectively In the branch fraction 5 -10 cm, MS and C:N were higher in the first evaluation with 52 g kg-1 and 77 than in the second one (42 g kg-1 and 62 respectively), and the N was higher in the second evaluation. with 7.2 g kg-1. In the branch fraction >10, there was significance for variables, MM concentrations, MO and N with 20; 980; 7 g kg-1 respectively were higher in the second evaluation compared to the first (15, 985 and 6 g kg-1 respectively). δ13C did not differ between fertilization levels, but δ15N was higher in treatments of 200 and 400 kg/N/ha/year with 1.04 and 1.73 ‱ respectively, Ndda was higher in treatments of 0 (76, 77%) and 100 (56.84%) kg/N/ha/year. There was no significant difference (P>0.05) between the levels of fertilization for animal performance (TL, ADG and GPA), MFT, %FV, %FS and chemical composition. Between the evaluation periods there was significance (P<0.05) for all variables, the TL ranged from 3.4 to 5.1 Ua between June/2020 and February/2021. The GMD and GPA were higher in the periods with the highest rainfall, ranging from 0.03 and 0.1 to 0.75 and 3.4 in the months of August/2020 and April/2021 respectively. The MFT ranged from 552 (August/2020) to 2216 kg/ha (February/2021). The %FV in the months of November and December/2020 and January and March/2021 was higher than the other months, reaching 87, 94, 81.86%, on the other hand, %FS was higher in the months of August, September and October with 64 , 62, 70%. The DF ranged from 14 (December/2020) to 84 kg of DM ha-1 cm-1 (February/2021). PBF concentrations ranged from 83 (October/2020) to 118 g kg-1 (March/2021), while PBFS differed only in June/2020 with 47 g kg-1. The MMFV differed only in March and April/2020 with 124 and 127 g kg-1, and the MMFS was lower in the months of Nov/2020 and Jan/2021. Fertilization did not differ in forage production and animal performance. In the agrosilvopastoral system, the different levels of nitrogen fertilization did not influence the dendrometry, biomass area, basic density and chemical composition of the thrush. The biological N fixation of the sabiá in the agrosilvopastoral system was higher at the levels of 0 and 100 kg of N ha-1 yr-1. The inclusion of leguminous trees in massai pastures resulted in significant increases in the CP contents of the pasture.

The use of fertilizers and other pesticides to meet the nutritional requirements of crops and increase production has, in some cases, generated an increase of hundreds of tons of potentially toxic metals to the soil, thus contributing to its impoverishment. However, some plant species are able to survive and adapt to environments contaminated with potentially toxic metals, in addition to removing large amounts of pollutants, characterized as phytoremediation plants. Experimental used was completely randomized (DIC) in a 5x2 factorial, with 5 doses of metallic species in the form of PA salts (0, 10, 20, 40 and 80 mg kg-1 ) and 2 inoculations of FMA (with and without FMA), totaling 10 treatments with 4 repetitions, resulting in 40 experimental units. The soils were incubated with the metallic species investigated in the form of P.A salts at doses 0, 10, 20, 40 and 80 mg kg-1. The determination of the percentage of organic matter was made by calcination at 550°C. In determining the cation exchange capacity, the method proposed by Cotta et al. (2006). Parameters were also determined: plant height, root length, chlorophyll index, shoot fresh matter, shoot dry matter, root dry matter, % root colonization and uptake of phosphorus, nitrogen and potassium. The extraction of bioavailable metals from the soil before and after planting was carried out using a 1 mol L-1 HCl extracting solution. Data were subjected to analysis of variance using the R statistical program and the comparison of means was performed using the Tukey test at 5% probability. Urochiloa brizantha showed good development in soil contaminated with different dosages of heavy metals. The soil had a low percentage of organic matter, characterizing itself as an inorganic soil. The metal that represented more bioavailability was Zn2+ with 473.867 mg kg-1 in doping and 80 mg kg-1 followed by Mn2+ with 190.508 mg kg-1 in 10 mg kg-1 doping and the one that was less bioavailable was Cu2+ with 2 mg kg-1. It was also observed that in the 20 and 40 mg kg-1 dopings, the F.M.A influenced the metal complexation in the soil, causing it to leach a lower concentration of metals.

Eucalyptus is a kind of fast growing cycle and widely used for the production of cellulose and paper. In recent decades, the expansion of cultivation has registered an aggressive increase in diseases in nurseries and forest plantations. And one of the most serious diseases that the Eucalyptus crop has been facing is wilt caused by the fungus Ceratocystis fimbriata. This fungus, when colonizing the plant, will obstruct the vascular system, and in response the plant forms tylos, gels or fungal material, which will promote the physical blockage of the xylem vessels and increase the resistance to the flow of water from the roots to the leaves, inducing the plant to water stress. As a result, the physiological functioning of the plant will be affected and its growth reduced, causing the plant to have symptoms such as wilt, cankers and root rot, which may even lead to death. Thus, this study aimed to evaluate the ecophysiological responses of Eucalyptus spp. inoculated with the fungus C. fimbriata. The treatments used were the isolates LPF 1512, 1806, 1607, 1657, from São Paulo, Minas Gerais, Bahia, Mato Grosso do Sul, respectively, and a control treatment, using only distilled water. Isolates of C. fimbriata were cultivated in a Petri dish filled with PDA culture medium (200g of potato, 20g of dextrose, 17g of Agar and one liter of distilled water), in a BOD-type incubator, at a temperature of 25 ± 1 °C and 12-hour photoperiod for 15 days. At the end of the fungal growth period, the suspension for inoculation was prepared, adding 10 mL of distilled and sterilized water to the plates with the fungal growth. With the aid of a sterilized Drigalsk loop, the surface of the fungal colony was scraped to obtain the suspension of the spores. Inoculation was carried out on the plants 60 days after planting. With the aid of a scalpel, a longitudinal incision was made in the epidermis of the plants with approximately 1 cm in length and 0.2 cm in depth and at a height of three centimeters from the plant's neck. 500 μL of conidia suspension is applied with an automatic pipette. After inoculation, analyzes of growth, gas exchange, leaf temperature and chlorophyll a fluorescence were performed. The study suggests that the resistance to water flow in the xylem vessels, imposed by colonization by C. fimbriata in the Eucalyptus clone VCC 795, regardless of the isolate used, resulted in a water deficit in the leaves and resulted in a reduction in gas exchange, in addition to impair photosynthetic performance, observed through reductions in active reaction center density (RC/ABS) and photosynthetic index (Pi), and all these triggered mechanisms resulted in a reduction in plant growth. In addition, the fungus severity analysis indicates that of the isolates used in the study, LPF 1657 was the one that most affected the physiology and growth of plants of the Eucalyptus clone VCC 795, a fact that was confirmed by the lower height values, A , gs and E, in plants inoculated with this isolate.

The objective was to evaluate the light intensity, type of sealing and sucrose levels in the morphogenic parameters of the “Pata de vaca” (Bauhinia forficata Link) crop. A completely randomized design was used, in a 2x2x3 factorial scheme (two light intensities - IL, two types of sealing - TV and three levels of sucrose - NS). The light intensity being 43 or 70 μmol m^-2s^-1, the type of sealing with or without membrane and the sucrose concentrations of 0, 20 and 30 g L^-1, totaling 12 treatments and 4 repetitions for each. B. forficata were obtained by donation, submitted to processes under aseptic conditions and packaged in paper bags for subsequent conservation in a refrigerator at 2 oC. In the laboratory, the seeds were subjected to aseptic conditions, then germinated in 350 mL disinfected glass bottles and kept for 30 days in a growth room. After these procedures, the evaluation began for a period of 45 days, using three nodal segments of the seedlings germinated in a 350 mL glass bottle, each bottle representing a repetition, which were distributed and submitted according to each treatment. At 30 days of culture, the shoot fresh mass (MFPA, g), shoot dry mass (MSPA,g), root fresh mass (MFR, g), root dry mass (MSR, g), plant length (CP, cm), leaf width (LF, mm), leaf length (CF, mm), number of leaves per plant (NF) and number of shoots (NB), were assessed. There were no significant differences in the ILxTVxNS interaction for any of the evaluated parameters. Significant differences were observed for the TVxNS interaction for the MRS variable, for the ILxNS interaction for the MPAS, MRS, LF and CF variables, and for the ILxTV interaction for the MPAS variable. A positive linear increase (P ≤ 0.05) was observed as the NS increased in the NB, CP, MPAF and MRF variables. TV influenced weight and size (P ≤ 0.05), with higher values being observed in the use of CM when compared to SM in the variables CP, MPAF, MRF, LF, CF and NF. Greater amount, size and weight (P ≤ 0.05) were observed in IL, in I70 they had more NB, CP, MPAF and MRF when compared to I43.

Babassu extractivism has already stood out as one of the three main productive activities in the agriculture context in Maranhão state, which had relevance concentrated in the ecological, conservationist, political and social areas. But from the 70's onwards, this scenario began to change, giving rise to a historical conflict between farmers and agro-collectors of Babassu coconut. In the 90's the process of organizing and articulating women-coconut-breakers began, generating the first “Encontro Interestadual das Quebradeiras de Coco Babaçu”, which resulted in the “Movimento Interestadual das Quebradeiras de Coco Babaçu” – MIQCB. This movement contributed to an agenda of struggle for these women, which prioritized issues related to the preservation of the environment and guarantees of free access and common use of palm trees. Thus, the breakers got more force in the “free babaçu” laws. However, even though the MIQCB has united the breakers and gained strength in recent years, they still cannot control the pressure that acquired babassu areas are suffering from large agricultural enterprises. Given this assumption, the creation of public policies for the protection of the palm tree may be a way to perpetuate this traditional culture in Maranhão that generates livelihood mainly for these families that depend on Babaçu.

Phytoremediation is an innovative proposal as an alternative methodology for the removal of organic pollutants, and the success of the technique depends on the careful selection of plants with favorable characteristics. Legume species exhibit favorable characteristics for growing rapidly in degraded soils, which is an important quality when considering the potential for phytoremediation of these contaminants. To reach the objective, bibliographical and experimental researches were carried out, organized in four chapters. Thus, this study aimed to valuate the physiological response, determine the tolerance and phytoremediation potential of C. ensiformes L. in increasing doses of copper and zinc in the soil. The experiment was carried out in a greenhouse, in a completely randomized design for both metals. The experiment was carried out in a greenhouse, in a completely randomized design for both metals. The soil was treated with four doses, in addition to the control of copper and zinc equivalent to (0, 10, 20, 40 and 80 mg kg^-1), with four replications, the species used was C. ensiformes. The first chapter is a literature review on potentially toxic metals, copper, zinc, phytoremediation and C. ensiformes. The second chapter aimed to evaluate the physiological responses of C. ensiformes cultivated in soil with increasing doses of copper and zinc. The variables analyzed were: green intensity, photosynthetic index (PI) and count of the number of nodules. In addition, chlorophyll a fluorescence variables were analyzed: initial fluorescence (F0), maximum fluorescence (Fm), variable fluorescence (Fv) and maximum PSII quantum efficiency (Fv/Fm). The results were submitted to ANOVA and regression test (p<0.05). Regarding the chlorophyll a fluorescence, it was found that the individuals presented rates outside normal, indicating a stress condition, there was a decrease in the Fv/Fm ratio and in the intensity of green at the dose 80 mg kg^-1. Photosynthetic indices revealed that C. ensiformes plants are sensitive to Zn and Cu contamination. Higher doses of metals caused fewer nodules. Therefore, it can be concluded that copper and zinc metals at high levels cause damage to physiological metabolism in C. ensiformes plants. The third chapter aimed to evaluate the phytoremediation potential of the species C. ensiformes cultivated in soil with increasing doses of copper and zinc. The variables analyzed were the growth morphometric: height, stem diameter and number of leaves, dry biomass and copper and zinc contents of shoot and root, translocation indexes and factors, bioaccumulation and tolerance. The plants of C. ensiformes during the experimental period were tolerant to the treatments used, however, doses of copper and zinc in the soil above 20 mg kg-1 reduced their growth. Zinc and copper contents were higher in shoots. The FT was greater than 1 for Zn showing that for this metal the plant was phytoextractor. Therefore, it can be stated that C. ensiformes is an economic and ecological alternative for metal remediation.

The aim of this study was to determine the relationship between soil attributes, corn productivity and agroecosystem change, defining a management capable of increasing the potential for corn production in structurally fragile soils in the Amazon region of Maranhão. The experiment was carried out between November and May, between the years 2019 and 2020, in the municipality of Pindaré-Mirim, MA, Brazil. This study was divided into two experimental tests: Experiment 1 - Determined which and how soil attributes influence maize yield. For this evaluation, 119 georeferenced sampling points were delimited, in a uniform degree of 9m x 8m, totaling an experimental area of 1 ha. Corn production was sampled in 6 m2 around the sampling points. To determine the physical attributes, a 30x30x30cm trench was opened, close to each sampling point. Experiment 2 - Determined the influence of different agroecosystems on soil fertility. Four agroecosystems were taken, each with approximately 1 ha: Forest, Pasture, Crop and Agrosilvipastoral System. For this evaluation, three trenches similar to those of the previous experiment were opened, in each land use, distributed at random. To remove the deformed ones, twelve equidistant points were distributed around each trench on the four first cardinals. In both experiments, two layers were sampled: 0-15 and 15-30cm. The physical attributes (particle composition, Ds, PT, MIC and MAC and RP), the chemical attributes (pH, P, Ca, Mg, K, Na, H + Al, T, CTC and V%) and as fractions were superior physical organic carbon (COT, COP and COAM). In experiment 1, descriptive statistics of the data, the Shapiro-Wilk normality test and the Bartlett homogeneity of variance test, the Pearson correlation test and the multiple regression by the stepwise method were performed, both at 5% significance, in addition to of Ordinary Kriging with isoline maps. In experiment 2, the same normality and homogeneity of variance tests were performed, with subsequent analysis of means comparison using Tukey's test (α = 5%). The soil attributes that influenced maize yield were COAM, RP and pH, and indirectly the Ca contents. In fragile tropical soils, the agrosilvopastoral system represented an excellent strategy for conservation and environmental recovery.

Studies on land use and occupation on larger scales are increasingly necessary, since they promote a more accurate diagnosis of the landscape, and thus contribute to the elaboration of plans for the land use, minimizing environmental degradation processes along hydrographic basins. The objective of this study is to identify and characterize the time-space dynamics of land use and occupation in the Rio Lajeado basin, state of Maranhão, which is fully inserted in the Cerrado Biome. Images from the Landsat-5 (TM) satellite, for the years 1986, 1996 and 2006 and Landsat-8 (OLI), for the year 2018 were used. The software QGIS 3.4.8 was used for the digital processing of the images and supervised classification of images using the Random Forest algorithm installed in this software. As for the accuracy of thematic maps, the AcATaMa plugin was used, in which we adopted the model of random sampling by extracts, that is, the samples generated take into consideration the proportion of the classified class in relation to the area. All classifications showed results of global accuracy greater than 80%. In the analyzed period, we noticed important changes, considering that in 1986 the area under study was occupied by 84.61% of natural formations, and as the years passed, this scenario was significantly modified, and in 2018 the natural formations represented 53.26% of the study area. There were also the emergence of two classes of land use and occupation, bananas and silviculture with eucalyptus plantations. Among the non-natural classes, pastures stood out, occupying an area of 43.18% in 2018, and becoming the largest driving force responsible for landscape changes in the Lajeado river basin. Therefore, the results obtained by remote sensing techniques are very important, since pasture, forestry and banana farming activities, close to water courses, can cause numerous environmental impacts, due to the deforestation process to introduce these new activities. Deforestation of natural formations can lead to loss of biodiversity and habitats, soil erosion, silting of streams and climate changing. Not only with deforestation, can there be environmental impacts, but we also have environmental impacts associated with the management of these activities, due to the use of pesticides, large use of water for irrigation of perennial crops, soil compaction due to cattle grazing, contamination of streams and soil by cattle faeces.

In the municipality of Pindaré-Mirim and in other regions of the Amazon, the practice of converting native forests into pastures for traditional cattle ranching or agricultural areas, which quickly reach the stage of degradation, is predominant. In this sense, the work aims to measure the physical and chemical attributes of the soil in chronossequence of pasture in a crop-livestock-forest integration system, in Pindaré-Mirim, state of Maranhão, Brazil. For the purpose of evaluation, the experiment included two reference environments: capoeira with secondary vegetation in regeneration for approximately 20 years and native babassu forest with soils collected before the project started; and five succession seasons: degraded pasture, ILPF 2016, 2017, 2018 and 2019 that were compared with the reference environments. Undisturbed samples were collected to determine physical attributes (density, macroporosity, microporosity and total porosity) in the layers: 0-10, 10-20, 20-30 and 30-40 cm. For the chemical attributes (pH, MO, P, Al, H + Al, SB and V) of the soil, deformed samples were collected in the same layers. For the analysis of carbon content and stock, the analyzes included layers 0-10, 10-20, 20-30, 30-40, 40-60, 60-80 and 80-100 cm. With the data in hand, analysis of variance was performed and a means test was used (Tukey, 5% probability), and multivariate analysis (analysis of main components and grouping) was performed. Pasture in the second year of ILPF (2017) shows lower values of macroporosity and total porosity in all studied layers, however in ILPF 2019 it presented higher values of macroporosity. For layers 0-10, 10-20 and 30-40 cm, the phosphorus and base saturation variables showed higher values in ILPF 2018. The 20-30 cm layer in ILPF 2018 management showed higher values of P, MO, pH and microporosity. ILPF 2017 shows dissimilarity from other land uses from the point of view of soil physics variables, while ILPF 2018 was for chemical soil improvement. The increase in accumulated C stock (0-100 cm) in relation to Native Forest with the use of pasture in ILPF of 2018 after the corn-grass consortium was 16%. ILPF pasture in 2018 increased the carbon stock (0-100 cm) by 31% compared to degraded pasture (2016).

The objective of this study was to evaluate the behavior of different native plants from the Cerrado of Maranhão, ipe-purple (Tabebuia impetiginosa) and aroeira (Myracrodrun urundeuva) in phytoremediation of soil contaminated by Mn (II) and Zn (II) under greenhouse conditions. Soil collections were carried out in a preserved area in the city of Imperatriz-Ma and physical-chemical analyzes were performed: pH in water and KCl, cation exchange capacity, organic matter content, adsorption tests, efficiency calculations and analysis of their bioavailability. The results indicated that the soil has acidic characteristics, a tendency to retain cations, with low and medium cation exchange capacity, predominance of inorganic materials and minerals incorporated in the soil and that the metals Zn and Mn have a high content of bioavailability. For the phytoremediation experiment, Tabebuia impetiginosa and Myracrodrun urundeuva seedlings were grown in a greenhouse. A completely randomized design (DIC) was used, constituting 12 treatments with 3 repetitions, resulting in 36 experimental units. After the experimental period, metal extraction of the species was performed, metal determination by Flame Atomic Absorption Spectrometry (FAAS) and calculations of Bioconcentration Factor (BCF) and translocation factor (FT). The analyzes of variances for independent samples (ANOVA) were obtained, with the averages compared by the t test at 5% probability, the statistical analyzes were performed in the IBM SPSS Statistic.Among the species investigated, T. impetiginosa presented a biomass production (aerial part / root) greater than M. urundeuva in the period of 25 days. In the 45 day period, the root biomass was higher in T. impetiginosa in doped soil and the lower biomass production was verified in the control group of M. urundeuva. Regarding the content of Mn in the root, T. impetiginosa in the period of 45 days in doped soil obtained the highest concentration of the metal. With respect to T. impetiginosa, the Mn concentrations showed significant differences in the plant root over a 45-day period in doped soil 130.74 mg kg-1. In the aerial part, Mn showed higher concentrations in M. urundeuva in the period of 45 days in control soil, 335.80 mg kg-1 and in T. impetiginosa in the period of 25 days in doped soil, 256.10 mg kg-1. The highest concentrations of Zn in the root were observed in the 25 day periods of the doped soils of both species, with absorption of 142.10 mg kg-1 for T. impetiginosa and 150.57 mg kg-1 for M. urundeuva. In the aerial part the concentration of Zn was higher in the species M. urundeuva in doped soil in the period of 45 days 398.97 mg kg-1. For FT and BCF, T. impetiginosa showed efficiency in phytostabilization and
phytoextraction for both metals. M. urundeuva had phytoextractive behavior during the 45 days of cultivation. In the period of 25 days in doped soil M. urundeuva behaved as a phyto-stabilizer, retaining and immobilizing metals in the soil. The two species studied showed good tolerance to manganese and zinc metals in soils.

Insects are excellent models to study the effects of modified ecosystem on diversity patterns and ecosystem functioning, modifications being either human made or naturally occurring events. In Class Insecta, dipterans are appointed as bioindicators to be used in impact assessment and environmental monitoring, as they can provide responses to changes caused in their habitat by anthropization, vegetation gradient modification, and possibly by fire events. Therefore, faunal and ecological studies carried out in Chapada das Mesas National Park region are essential, as this Conservation Unit is located in a biodiversity hotspot, and has been suffering from anthropogenic disturbances, native vegetation loss and fires. Thus, our aim was to study patterns of species composition, richness and abundance of necrophagous fly communities (Calliphoridae, Mesembrinellidae and Sarcophagidae), verifying the possible effects of vegetation cover and fire events on species composition, richness, abundance and diversity of this fauna in Chapada das Mesas National Park. We observed that the communities of the three families sampled had a different distribution pattern according to the vegetation cover of each phytophysiognomy. The most opened environments were those with the highest estimated species abundance and species richness for families Calliphoridae and Sarcophagidae. Mesembrinella bicolor (Fabricius, 1805), the only species from family Mesembrinellidae found in this study, occurred only in forest phytophysiognomies (seasonal forest and riparian forest) and showed as a good indicator for these areas. Sarcophagidae, in general, had a higher occurrence in open areas due to its heliophilic behavior. In relation to the environmental variables, califorids had a higher relationship with the types of phytophysiognomies found in the park, and showed higher abundance on rainy days, while arcophagids were better adapted to the areas that had more fire events. Therefore, this work suggests directing efforts towards the conservation and preservation of the protected areas of the Chapada das Mesas National Park, which have been undergoing anthropization processes, in order to minimize the impacts caused on the scavenger dipter communities, as well as to understand better how changes in the fire regime can affect these communities, since it was observed in this study that fire can be an exclusion factor for many species of the group califorids + mesembrinelids, while favoring the colonization of areas burned by species of sarcophagids.

Agricultural expansion in the South region of Maranhao state, Brazil, has been impoverishing Cerrado biome landscape with soybean monocultures. It exerts a negative effect on richness of insect species that have been noted from changes in their composition. Insects have an important role in ecosystem services and they are useful for measuring ecological quality of environments. The present work evaluated the effect of habitat impoverishment on richness, abundancy and composition standards of insect species present in the entomofauna of a soybean monoculture area, compared to a legally protected area, all located in Balsas, state of Maranhao, Brazil. Insect sampling was carried out with Provid and Moericke traps, and also with active collecting using entomological nets. There have been two collection periods during the soybean phenological cycle: one during inflorescence and another during maturation, at the same time of the collections in legally protected area. An amount of 9345 insect samples was collected and classified in 15 orders, 93 families and 383 morphospecies. More abundant orders were Hemiptera, Hymenoptera, Dipteran and Coleoptera. Overall, field observations suggested that habitat impoverishment significantly reduced richness of species in the soybean monoculture, but did not seem to have a negative effect on abundancy. Species composition in the entomofauna of the four main sampled orders showed similarities between insect communities in the soybean monoculture and legally protected area, suggesting existence of insect rotativity. Scarabaeidae and Formicidae have confirmed their bioindicator potential in this study, since they presented themselves more diversified and abundant in the legally protected area. This study suggests that ecosystem services in these areas have contributions from the following insect families: Dolichopodidae, Carabidae, Formicidae, and Apidae. Thus, it is emphasized the importance of conserving vegetation in native areas of Cerrado biome next to agricultural lands.

With the expansion of forest plantations in the national territory and the imminence of the increase in temperatures due to global warming, it becomes relevant to approach technologies that favor survival and greater growth of seedlings after planting and consequently increase productivity in the field. The application of particle films based on calcined kaolin has been used as a protective barrier against the deleterious effects of solar radiation and excess temperature. The present project aims to evaluate the effects of the application of particle film based on purified calcined kaolin in eucalyptus plants, in vase and field conditions. In the two cultivation conditions, five treatments will be established: control (without application of the particle film), 3%, 5% 7% and 10% syrup volume. The application will be performed on the adaxial part of the sheets. The experimental design will be completely randomized, presenting five treatments with 10 replicates, totaling 50 experimental units for each cultivation condition. The plants will be evaluated for height, diameter at soil level, leaf temperature, gas exchange (photosynthetic CO2 assimilation, stomatal conductance and transpiration), water use efficiency, maximum quantum yield of photosystem II, green intensity and foliar ontogeny.

The intensification of products consumption by humanity obtains as a result the making of great amounts of solid residues which are commonly discarded in open air places named "lixões"¹. Among the effluents deposited in lixões are the heavy metals that, in some conditions, may act in a harmful manner, justifying studies over such substances. The Diptera from the family Calliphoridae, known as flies, are also found in urban rural and forest areas, attracted by substances in the process of decaying. Therefore, these characteristics attribute them the capacity of being used as bioindicators of anthropogenic interferences in natural environments. Consequently, this study aims to resort to Synanthropic fly species from Calliphoridae family as bioindicators of the concentration of metals potentially hazardous in anthropized territories (lixões). There has been used 200 traps for the capture of necrophagous Diptera in the surroundings of Balsas and São Raimundo das Mangabeiras (MA), making 100 in the areas of the towns' solid residues (lixões) and another 100 in Brazilian's protected Cerrado area. Moreover, there were also collected soil samples in the spots of the settlement of the traps. Succeeding this process, there was made the analysis of levels of potentially toxic metals, both in flies and in the soil samples gathered. There were collected 27.933 Diptera belonging to 11 families, from which 17.767 were in anthropized environment and 10.166 in Brazilian's protected Cerrado. The most abundant families were Muscidae (35,4%), Calliphoridae (23,5%), Otitiidae (20,9%), Sarcophagidae (16,1%) and Faniidae (3%). Out of the Calliphoridae family were collected 6.560 specimen, making 4.550 in the anthropized environment and 2.010 in Cerrado, sorted in 04 genera and 06 species, giving due prominence to Chrysomya megacephala (45,53%), Chrysomya albiceps (27,52%), Cochliomyia macellaria (11,36%) and Chloroprocta idiodea (10,38%). Excluding an anthropized area where were presented 10,40 %, another areas presented organic material rating less than 10%. The water's pH indicates that in the analysed soils, in general, contain acidic character. The pH in water was higher than the pH in KCI. ∆pH and PCZ revealed occurrence of negative charges in both environments. The anthropized environment showed larger concentration of the metallic species analyzed (Cd, Pb, Cr, Mn e Zn) both on the soil and in the flies, considering that the Cadmium's were below the quantity of detection in the ground. The same has happened to lead in flies in preserved environment. Both three species investigated from the family Calliphoridae (Chrysomya megacephala, Chrysomya albiceps e Chrysomya putoria) presented high potential of bioaccumulation for Cr, Mn e Zn. There was a tendency of better indication of metals by female specimen.

¹ landfills or garbage dump (in informal language), however, the denomination is considered a proper name in Portuguese. Therefore, it may not be translated accurately.

Our objective was to develop nitrogen indices based on SPAD indices as a non-destructive tool to predict N state and corn yield throughout crop development. Five N rates (0, 30, 60, 120 or 180 kg ha-1) applied as cover were used to create variability in the nitrogen indices evaluated in corn plants. A randomized block design with four replications was used. The AG1051 corn hybrid was used. The SPAD value was obtained in four fully expanded leaves from the plant apex in five phases of vegetative growth (V5, V7, V11, anthesis and milky grain). Subsequently, the SPAD value was used to calculate Normalized SPAD Index (ISN), Relative SPAD Index (ISR), SPAD Index Difference (DIS), Relative SPAD Index Difference (DISR), and SPAD Index Difference normalized (DISN). Also, in each growth phase were determined leaf N (TNF) and plant N (TNP), nitrogen nutrition index (INN) and plant accumulated N (NA). INN values ranged from 0.47 to 1.53. INN values were greater than 1.0 for all doses of N at stage V5 except for N0 (INN = 0.99) and V7. This indicates that plant growth was not limited by N rates. N rates increased quadratically the grain yield. The 114.2 kg ha-1 N rate provided the maximum grain yield of 2955.4 kg ha-1. In phase V7, grain yield showed the highest correlation with the SPAD value obtained on leaf L1 (r = 0.72; p <0.01) and the lowest correlation with ISN2 (r = 0.52; p <0, 05). This indicates that 52% of grain yield was explained by the SPAD value. The results of correlations between SPAD and N indices indicate that leaves L1 and L2 are the most sensitive for SPAD reading in the early stages of maize. The initial stages V5 and V7, and leaves L1 and L2 were the ones that showed the highest significance and r2 of SPAD indices with the 4 N indicators, but with low or no significant relation for L1 leaf in V11.

Studies in the area of allelopathy in agriculture have increased due to searches of alternative methods in weed control over conventional herbicides. Lippia origanoides is a plant native to South and Central America that has several chemotypes and has been a major target for research due to its medicinal properties. Thus, the objective of this work was to evaluate the chemical composition and phytotoxicity of the essential oil of Lippia origanoides in weeds of the species Bidens subalternans, Euphorbia heterophylla and Macroptilium lathyroides in laboratory conditions and greenhouse. The essential oil was extracted from the leaves of L. origanoides by hydrodistillation and diluted at concentrations of 0.01%; 0.05%; 0.1%; 0.5% and 1%. The chemical composition was determined by gas chromatograph coupled to the mass spectrometer. Phytotoxic activity was evaluated in pre and post-emergence by germination, seedling growth, chlorophyll content and cellular respiration tests. The chemical analysis demonstrated an essential oil rich in monoterpenes, mainly oxygenated, with camphor, camphene and βBisabolene as major compounds. In general, both germination and seedling development were strongly inhibited by essential oil, decreasing with increasing concentrations. The concentrations 0.5 and 1.0% totally inhibited the germination of B. subalternans, but did not affect the germination of M. lathyroides. The essential oil sprayed on weed leaves had no effect on chlorophyll content but was able to induce visible lesions such as necrosis and chlorosis. Only the cellular respiration of E. heterophylla was affected by the essential oil. All phytotoxic effects observed are due to the high concentration of monoterpenes in the essential oil, mainly oxygenated, as well as the concentration used.

Bioremediation uses microbial metabolism to reduce or decontaminate pollutants. The herbicides, when used intensively, contaminate the soil, making necessary the degradation of these molecules. The objective of this work was to evaluate the bioremediation of soils supplemented with atrazine, glyphosate and pendimethalin by consortia of fungal lineages isolated from agricultural soils, in the biodegradation processes in microcosms in Imperatriz - MA. Soil samples were collected from three areas for physical-chemical analysis and fungal isolation. Isolation was by serial dilutions and selection was performed in KATAYAMA culture medium at the concentrations 0, 10, 20, 50 and 100 μg mL-1 of the herbicides. The microorganisms were selected by macroscopic observations after 14 days of incubation. These strains were plated in a 4% sabouraud dextrose culture medium supplemented with 0, 10, 20, 50 and 100 μg mL-1 of the herbicides and incubated for seven days at 28 ° C, then the mean mycelial growth of the lines. In order to detect the degradation activity, microcosmos tests with 0 and 50 μg mL-1 of the herbicides were carried out for 15 days. The consortia were formed based on the evaluation of the CO2 release of the isolated strains. From the calculations of respiration curves were constructed that indicated the metabolizaton of the herbicides. In the genotoxicity analysis, Allium cepa roots remained in contact with the elutriates of the soils supplemented with the herbicides in the contractions 0 and 50 μg mL-1 for 24 hours, then were collected and analyzed for mitotic index determination and occurrence of cell changes. The data were submitted to statistical analyzes at p <0.05%, with the aid of the Sisvar program. Three fungal strains proved to be suitable for the degradation of herbicides, namely: Aspergillus fumigatus, Fusarium verticillioides and Penicillium citrinum. In the mean of mycelial growth in the presence of atrazine, the fungus Fusarium verticillioides showed the highest growth and the concentrations 10 and 20 μg mL-1 were more favorable. The fungus Fusarium verticilliodes and Aspergillus fumigatus had the best means and the growth was more pronounced in 10 μg mL-1. In the presence of pendimethalin, the fungus Fusarium verticilliodes showed better performance and the best results were 10 μg mL-1. In the microcosms, Aspergillus fumigatus and Penicillium citrinum presented the best rates of CO2 release for atrazine; Aspergillus fumigatus presented greater CO2 release for glyphosate and Penicillium citrinum had the highest rates for pendimethalin. The consortium Aspergillus fumigatus - Penicillium citrinum presented higher release of CO2 in the presence of atrazine, but this consortium showed growth inhibition and was not efficient for glyphosate and pendimethalin. In the genotoxicity test, a delay in the mitotic index was observed in the treatments with 50 μg mL-1 of atrazine herbicide elutriates treated with the Fusarium verticillioides - Aspergillus fumigatus, Fusarium verticillioides - Penicillium citrinum and Aspergillus fumigatus - Penicillium citrinum and pendimethalin treated with the consortium Aspergillus fumigatus - Penicillium citrinum. In the treatment with glyphosate elutriate treated with the consortium Aspergillus fumigatus - Penicillium citrinum, no delay in the mitotic index was observed. Only disorganized cell division in the metaphase phase was found in the treatments with 50 μg mL-1 of the three herbicides, but the alterations were considered low, indicating that the herbicides were degraded.

Understanding the spatial variability of soil attributes allows the farmer to implement precision farming on his property by ensuring optimization in the productive process and yield increases due to the proper management of specific sites and generation of yield maps. The objective of this paper was to determine and map spatial variation of soil physical attributes and maize productivity components in an area under no-tillage, as well as to characterize the relationship between these attributes to obtain variables with potential for the recognition of specific sites of management. The study was conducted at Fazenda Santa Luzia, located in the municipality of São Raimundo das Mangabeiras, MA, in an experimental area of approximately 0.7 ha, managed under no-tillage. The soil physical parameters and  maize crop yield were evaluated with the support of a 10 x 10 m grid, where the sampling points corresponded to the intersection between the rows and columns of the grid. In each sampling point, the geographical coordinates were recorded with GPS Garmin 76CSx, collection of undisturbed soil samples with volumetric rings of 100 cm³ in the depth 0.0-0.2 m, soil resistance measurement with penetrometer Falker PLG 1020 in the 0.05, 0.06-0.10, 0.11-0.15, 0.16-0.20 cm depth, collection of deformed samples at the depths of 0,0- 0.1 and 0.11-0.20 m to determining moisture at the time of sampling and harvesting of corn in an area of 4 m², totaling 100 samples. Soil density (Ds), total porosity (Pt), macroporosity (Ma), microporosity (Mi), fine sand content (AF), coarse sand content (AG), silt content (Si), clay content (Ar), penetration resistance (RP1, RP2, RP3, RP4), maximum  pressure (Pm), the maximum pressure depth (Ppm), moisture (UD1 and UD2), ear weight (PE), weight of one hundred grains (PCG), number of grains per ear (NGE), productivity (Prod). The data were submitted to descriptive analysis, exploratory analysis, Kolmogorov-Smirnov (K-S) normality test, Pearson's correlation, modeling and adjustment of semivariograms, ordinary kriging and generation of thematic maps. From the correlation analysis, positive correlation was obtained for the coarse sand and maximum pressure variables, and negative correlation for silt content and depth of maximum pressure. It was verified the occurrence of spatial dependence for most of the physical attributes of the soil and productivity components, with variation of the degree of spatial dependence between strong and moderate, except for moisture 0-10 cm, depth of maximum pressure, ear weight and number of grains per ear, which showed pure nugget effect. Ordinary Kriging was performed for the variables that exhibited spatial dependence, and generated isoline maps that allowed the visualization of the attributes variation of the studied and the identification of potential management areas.