The objective of this work was to evaluate seeds of cowpea, cultivar BRS Tumucumaque, subjected to different water stresses induced by polyethylene glycol (PEG-6000) and mannitol and different salt stresses induced by NaCl and CaCl2 solutions. The water and salt stresses was evaluated in laboratory using completely randomized experimental designs in 2x6 factorial arrangements, with six osmotic potentials (0.0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa) and two stress inducers for each experiment, with four replications of 50 seeds. The percentage of germination, germination speed index, root and shoot lengths and seedling fresh weight were evaluated at the tenth day (end of the evaluation period). The simulated water stress showed effects on the cowpea seed germination and seedling initial growth by decreasing the rates of the variables evaluated, which had greater effect in treatments with PEG-6000. The salt stress induced by NaCl showed greater effect on the variables evaluated than that induced by CaCl2, due to the sodium toxicity in the salt chemical composition.

Global climate change is closely tied to CO₂ emissions, and implementing conservation-agricultural systems can help mitigate emissions in the Amazon. By maintaining forest cover and integrating sustainable agricultural practices in pasture, these systems help mitigate climate change and preserve the carbon stocks in Amazon forest soils. In addition, these systems improve soil health, microclimate regulation, and promote sustainable agricultural practices in the Amazon region. This study aimed to evaluate the CO₂ emission dynamics and its relationship with soil attributes under different uses in the Amazon. The experiment consisted of four treatments (Degraded Pasture—DP; Managed Pasture—MP; Native Forest—NF; and Livestock Forest Integration—LF), with 25 replications. Soil CO₂ emission (FCO₂), soil temperature, and soil moisture were evaluated over a period of 114 days, and the chemical, physical, and biological attributes of the soil were measured at the end of this period. The mean FCO₂ reached values of 4.44, 3.88, 3.80, and 3.14 µmol m⁻² s⁻¹ in DP, MP, NF, and LF, respectively. In addition to the direct relationship between soil CO₂ emissions and soil temperature for all land uses, soil bulk density indirectly influenced emissions in NF. The amount of humic acid induced the highest emission in DP. Soil organic carbon and carbon stock were higher in MP and LF. These values demonstrate that FCO₂ was influenced by the Amazon land uses and highlight LF as a low CO₂ emission system with a higher potential for carbon stock in the soil.

Resumo: Na Amazônia brasileira, os assentamentos rurais encontram-se cada vez mais isolados por grandes fazendas de produção em larga escala, comprometendo a sua sustentabilidade e o bem viver dos agricultores familiares assentados. Trabalhos foram realizados em assentamentos para mensurar a sustentabilidade. Porém, a maioria não leva em consideração a participação e a coletividade dos envolvidos. O objetivo deste trabalho foi compreender a concepção dos agricultores familiares sobre a sustentabilidade e o bem viver bem como avaliar a sustentabilidade no Projeto de Desenvolvimento Sustentável - PDS São Paulo, na Amazônia norte mato-grossense. Utilizamos oficina e o sistema de semáforo para avaliar a sustentabilidade do PDS. A avaliação da sustentabilidade do assentamento nos permitiu compreender como a sustentabilidade e o bem viver vão se construindo no processo da história do assentamento. A sustentabilidade e o bem viver são processos dialéticos, estão em construção, em movimento.

The practice of liming may influence the leaching of herbicides in soils, especially those with weak acid character, such as picloram. The study on leaching, preserving soil structure, is an important factor when one intends to understand the dynamics of herbicides and environmental impacts. Thus, the effect of liming on picloram leaching in a dystrophic Red Yellow Latosol under field conditions was studied using a bioindicator plant. The experiment was set up in a completely randomized design (CRD), in split-plot scheme, with factorial in the plot. The factors of the plot corresponded to two soil conditions (presence and absence of liming) and 5 picloram concentrations (0; 384; 768; 1152; 1536 g ha-1), and the factor of the subplot was 5 soil depths (0-8, 8-16, 16-24, 24-32 and 32-40 cm), with four replicates. Pipes were introduced into the soil and, in part of the treatments, limestone was applied superficially. After ninety days, the different doses of picloram were applied on the surface of each pipe and these pipes were withdrawn after an accumulated rainfall of 128 mm, to perform the bioassay using cucumber plants (Cucumis sativus). Evaluations of plant development (phytotoxicity and shoot biomass) were carried out 21 days after sowing. It was concluded that picloram showed high leaching rate under all studied conditions and liming increased picloram leaching at doses lower than 768 g ha-1.

O cacaueiro (Theobroma cacao L.) é uma planta perene, da qual são extraídas amêndoas que vão ser usadas para produção de chocolate. O cultivo desta planta, especialmente no período de implantação da lavoura sofre a competição por plantas daninhas. Em geral estas são controladas com herbicidas. Entretanto estes produtos podem prejudicar ou até matar a cultura. O objetivo do presente trabalho foi avaliar o efeito de doses reduzidas, simulando deriva de glyphosate no desenvolvimento inicial de plantas de cacau. Foram testadas cinco subdoses do herbicida glyphosate: 0, 144, 288, 432 e 864 g e.a ha-1 do ingrediente ativo. Foram feitas avaliações aos 7, 14, 21 e 28 dias para verificação da fitointoxicação das plantas. Ao final de 14 e 28 DAA, foram avaliados: altura da planta, diâmetro do caule, número de folhas, comprimento radicular, matéria seca. Feita as análises foram observados que os sintomas de fitointoxicação foram severos já na primeira dose do herbicida afetando drasticamente o número de folhas das mudas de cacau. Sendo assim, nota-se que o cacaueiro é uma espécie que apresenta grande sensibilidade à deriva do herbicida glyphosate, e sua fitointoxicação ocorre já nas dosagens mínimas aplicadas.