Environmental contamination by heavy metals represents a growing concern throughout the world, and the physiological potential of the seed allows estimating the theoretical capacity to manifest its vital functions in stressful situations. Due to this, this work aimed to evaluate the effect of increasing dosages of nickel on the physiological potential of Brazilian mahogany (Swietenia macrophylla) seeds and seedlings, seeking to indicate the potential use of this species in phytoremediation programs for use as technology clean. The seeds were grown in polyethylene pots containing sand and maintained at a constant temperature of 28°C, relative humidity (RH) of 90% and a 12-hour photoperiod for 43 days. The experimental design used was randomized blocks, with five treatments (0, 2, 4, 6 and 8 mg.L-1 de NiCl2.6H2O), with six replications. Data were subjected to analysis of variance (ANOVA) and means were tested for significant differences by Tukey test using R-Studio-1.3.1093 software at 5% significance. Changes in plant growth and biomass were observed under different nickel concentrations. In stressful situations, seedling emergence decreased to 28.6%, the average emergence time was postponed to 25 days and there was a longer interval between the first and last seedling emergence, impacting stand establishment. Despite the variations, the seed was capable of emerging, developing and surviving environments contaminated by nickel, indicating some resistance to metal stress.

Light and hormones are factors that influence plant growth and development. This study aimed to observe the effect of different concentrations of 24-epibrassinolide combined with varying levels of shading on the development of Genipa americana L. seedlings. The seedlings were placed under three shading conditions: Full sunlight, 35%, and 50%. They were then exposed to five concentrations of the hormone: 0, 10, 20, 30, and 40 nM. The experiment was arranged in a randomized block design with four blocks and five treatments, containing 20 replicates/treatment/shading condition. The results revealed that moderate shading (35%) was the optimal condition for the growth of G. americana seedlings, yielding the highest diameter (12.12 mm) and height (35.3 cm) values. Although the number of leaves was greater in the full sunlight treatment (n = 12.2), no statistically significant difference was observed compared to the 35% shading treatment. At low concentrations (10 and 20 nM), 24-epibrassinolide effectively improved growth parameters and biochemical content. The 35% shading condition provided the best overall growth, resulting in higher values for height, diameter, and leaf number, making it the most favorable environment for robust development. Thus, combining appropriate shading with hormone treatment can optimize cultivation practices, providing an effective strategy for enhancing plant growth and adaptation in varying environments.

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.