Cowpea is a leguminous plant belonging to the fabaceae family cultivated in the North and Northeast regions of Brazil, with productive potential. Among the abiotic factors, water deficiency is one of the main environmental limitations that influence agricultural production in the world. The objective of this work was to study the relative water content and osmoregulators of cowpea plants subjected to water stress. The experiment was carried out in a greenhouse at the Universidade Federal Rural da Amazônia (UFRA, Belém, PA), cowpea plants BR-17 Gurguéia Vigna unguiculata (L.) Walp were used. The experimental design was completely randomized (DIC) in a 2 × 2 factorial scheme, two water conditions (control and water deficit) and two times of stress (four and six days of water suspension), with 7 replications, totaling 28 experimental units. The water deficit affected plants, causing a reduction in relative water content (69.98%), starch (12.84% in leaves and 23.48% in roots) and carbohydrates (84.34%), and an increase in glycine-betaine, sucrose (114.11% in leaves and 18.71% in roots) and proline (358.86%) at time 2. The relative water content was negatively affected by water conditions, with a decrease in relation to the interaction of the aerial part and the root system. Therefore, greater metabolic responses were noted in plants that were subjected to stress treatment at time 2 (6 days).

The cowpea bean [Vigna unguiculata (L.) Walp.], a legume of great socioeconomic importance, it was previously cultivated exclusively for subsistence and commercial purposes, especially in the North and Northeast regions. This crop has a low production cost and high nutritional value, in addition to a high potential for productivity growth and expansion to other regions. The objective of this work was to evaluate parameters of growth and production in cowpea culture, as a function of potassium fertilization in soil of the cerrado of Amapá. The parameters of growth and production of the cowpea culture were evaluated, as a function of potassium fertilization in the soil of the cerrado of Amapá. The experiment was conducted in a greenhouse, using a completely randomized experimental design, with four replications, in a 5x2 factorial scheme, totaling 40 experimental units, which were composed of plastic pots containing 7 dm³ of soil collected from the arable layer (0-20 cm ) of a typical Hyperdystrophic Yellow Argisol, with a sandy clay loam texture, in a cerrado area in the municipality of Porto Grande-AP. The factors consisted of the control treatment (without K), four doses of K (45, 90, 135 and 180 kg ha^-1) in the form of potassium chloride, and two cowpea cultivars (Pretinho and BRS Tumucumaque). The cultivar BRS Tumucumaque shows better growth and production of cowpea plants. Doses of 90 kg ha^-1 provided greater height (98.75 cm) and stem diameter (10.0 mm). As for production, the dose of 135 kg ha^-1 caused greater grain weight gain (5.25 g) and dry mass of pods (13.92 g), and the doses of 90 and 180 kg ha^-1 induced greater number and length of pods (3.16 pods) respectively. These results show better responsiveness of the BRS Tumucumaque cultivar at doses of 90, 135 and 180 kg ha^-1 in the type of soil where the study was conducted.

O potássio é o segundo macronutriente mais exigido pela cultura da soja e desempenha papel vital no processo fotossintético das plantas. Assim foi estudado o crescimento de cultivares de soja, em solo submetido à aplicação de doses de K. O experimento foi conduzido em casa de vegetação no Instituto Federal do Amapá – IFAP/Campus Agrícola Porto Grande. O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 5x2, com quatro repetições. Os fatores foram constituídos de cinco doses de K (0, 45, 90, 135 e 180 kg ha-1 de K), na forma de cloreto de potássio e duas cultivares de soja (BRS Sambaíba RR e BRS 8781). As unidades experimentais foram compostas por vasos plásticos, contendo plantas de soja, com 7 dm3 de solo, coletado na camada arável de um Latossolo Amarelo Distrófico de textura franco-arenosa. As variáveis analisadas, foram: altura da planta, diâmetro do colmo e matéria seca da parte aérea, das raízes e total das cultivares de soja. A dose de 90 kg ha-1 de K proporciona maior crescimento e produção de matéria seca da soja. A cultivar Sambaíba RR proporciona maior desempenho em crescimento das plantas de soja, em comparação a cultivar BRS 8781.

Anthropogenic activities such as industrial and mining activities have caused biotic and abiotic stress in plants through contamination by heavy metals deposited in the environment. Some of these are toxic to the plant in any concentration. Phytoremediation and its techniques then emerged as a measure capable of reducing heavy metal contamination. In addition to phytoremediation techniques, research shows the use of growth regulators to act as attenuators and mitigators of stress caused by heavy metals in plants. Thus, the objective of this bibliography was to gather information on contamination by heavy metals in Amazonian forest species, and to outline possible pathways and mechanisms capable of reducing this problem, enabling the use of specific species that can carry out phytoremediation of the soil, making contaminated and unproductive areas into productive ones and capable of being used in forest restoration programs and recovery of degraded areas. Understanding and studies on phytoremediation and its techniques have been deepened. However, it is necessary to increasingly understand the behavior of different species in the presence of heavy metals in the soil.

No cultivo de milho no estado do Maranhão, a cultivar híbrido Feroz VIP 3 é uma boa opção devido à sua resistência e adaptabilidade às condições climáticas. Além disso, apresenta resistência a pragas e doenças. Entretanto, para garantir uma boa produtividade é recomendado a utilização de fertilizantes para uma nutrição adequada das plantas e o uso de bioinsumos, incluindo Azospirillum brasilense e Bacillus subtilis, para promover o melhor desenvolvimento. O presente estudo teve como objetivo analisar e avaliar o metabolismo do carbono e nitrogênio em plantas de milho cultivar Feroz VIP 3 submetidos a aplicação de bioinsumos Azospirillum brasilense e Bacillus subitillis no leste maranhense. O experimento foi realizado na Universidade Federal do Maranhão, Campus de Chapadinha, em condições de campo. O delineamento utilizado foi em blocos inteiramente casualizado em esquema fatorial 2x3, com quatro repetições, totalizando 24 unidades experimentais. Sendo o fator A correspondente Azospirillum brasilense (com e sem bactéria) e o fator B corresponde as doses de Bacillus subtilis (0, 5 e 10 L.ha-1). As variáveis analisadas no experimento foram carboidratos solúveis totais, sacarose, amônio livre, aminoácidos solúveis totais e os teores de proteínas solúveis. A inoculação com Azospirillum brasilense e aplicação de diferentes doses de Bacillus subtilis afetaram o metabolismo do nitrogênio e o metabolismo do carbono. A aplicação Azospirillum e Bacillus subtilis apresentou respostas positivas para o aumento dos teores de amônio e aminoácidos na dose 0 L.ha-1. A aplicação conjunta de Azospirillumbrasilense e Bacillus subtilis podem melhorar o metabolismo do carbono e do nitrogênio nas plantas.

The objective of this work was to evaluate the biometric parameters, photosynthetic pigments and the antioxidant system of Clitoria fairchildiana R.A Howard seedlings subjected to exogenous application of 5-aminolevulinic acid and different concentrations of cadmium (Cd). The experiment was conducted in a greenhouse from May to August 2023. Initially, seedlings were produced from straw seeds. After three months, they were transplanted into 3 kg pots containing previously corrected and fertilized black soil. Ten days after transplanting, the plants received exogenous application of 5-ALA, weekly for 5 weeks, totaling 5 applications. After three days of acclimatization, cadmium concentrations were applied in a single time (42nd DAT), in the form of Cadmium Chloride (CdCl2.H2O): 0 (Control), 15 and 30 mg/L-1. The experimental design was completely randomized blocks (CRB), in a 3x3 factorial scheme, specified as follows: three concentrations of Cd (0, 15 and 30 mg L-1 of CdCl2.H20); and three concentrations of 5-ALA (0, 50 and 100 mg L-1 5-ALA), with 9 replicates. The main biometric and photosynthetic pigment variables showed changes with the application of 5-ALA and little variation in the levels subjected to the presence of cadmium. For the antioxidant system, the activity of the enzymes guaiacol peroxidase (G-POD), ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) suffered oscillations in their levels due to the application of 5-ALA and Cd, varying according to the concentration of the metal and the part of the plant.