Brackish waters has been increasingly used in hydroponic systems for the cultivation of vegetables. However, its use can cause significant losses in crop production. Therefore, new alternatives to enhance the tolerance of plants to salt stress are being studied, including seed priming with hydrogen peroxide (H₂O₂). Thus, this study aimed to assess the seed priming with H₂O₂ at different periods of exposure for enhancing the production, water status and pigments concentration of crisp lettuce grown under salt stress. The experiment was carried out under protected conditions, in a completely randomized design, with four replicates. The plants were cultivated in a floating hydroponic system, containing nutrient solution. Five treatments were tested: control (absence of H₂O₂ and absence of NaCl); salt control (absence of H₂O₂ and presence of 100 mM NaCl); 0.1 mM H₂O₂ (12 hours) + 100 mM NaCl; 0.1 mM H₂O₂ (24 hours) + 100 mM NaCl, and 0.1 mM H₂O₂ (36 hours) + 100 mM NaCl. In general, salinity reduced the height, production of the fresh and dry mass of the shoot, relative water content, and chlorophylls concentration of lettuce plants. However, the application of 0.1 mM H₂O₂ for 12 and 36 hours on the seeds, enhanced the growth, water status, and chlorophylls concentration of the plants. Seed priming with H₂O₂ at a 0.1 mM concentration for 12 hours can be recommended to increase tolerance of lettuce plants grown in a hydroponic system under salt stress.

The use of resources derived from the agricultural property itself to meet the needs of producers promotes the reduction of costs with commercial inputs and recycling of by-products, among them the liquid waste from the cassava flour production, called cassava wastewater, which can be an important fertilization source. This study aimed to evaluate the growth and production of Capsicum chinense Jacq., as a function of cassava wastewater doses associated with mineral fertilizer proportions. The experiment was conducted in a greenhouse, in a completely randomized design, with treatments distributed in a 3 x 5 factorial scheme, corresponding to 3 doses (0, 50 and 100 %) of the mineral fertilization recommended for the crop and 5 doses (0, 25, 50, 100 and 150 m³ ha-1) of cassava wastewater, with 4 replicates. The cassava wastewater doses influenced the crop yield, showing a linear trend. The dose of 150 m3 ha-1 promoted a yield equivalent to that obtained with the application of 100 % of the mineral fertilization recommended for this crop, thus enabling the partial or total replacement of this fertilization by cassava wastewater.

Understanding the leaf area is essential in plant physiology and ecological studies, as it directly influences photosynthesis, transpiration and plant productivity. This study aimed to develop non-destructive allometric models to estimate the leaf area of three species from the Caatinga biome: Cynophalla flexuosa, Libidibia ferrea and Tabebuia aurea. A total of 1293 leaves were collected from these species, scanned, and analysed using ImageJ software to obtain their length, width, and actual leaf area. In addition, the product of length and width was calculated. Linear, power and exponential regression models were used. The best equations were chosen based on the coefficient of determination, Pearson’s linear correlation coefficient, Willmott’s agreement index, mean squared error, root mean squared error, mean absolute error and mean absolute percentage error. The best equations for all species were constructed using linear and power models, which were indicated for accurate prediction of leaf area. These findings confirm the efficiency of allometric equations as a non-destructive method for predicting leaf area, providing an accessible and economical alternative for ecological studies in semi-arid environments.

Salinity represents a significant challenge for agriculture, especially in semi-arid regions, affecting the growth and productivity of plants such as nasturtium (Tropaeolum majus), which is valued for its ornamental, medicinal, and food uses. Salt stress disrupts biochemical, physiological, and anatomical processes, limiting plant development. This study investigated the application of attenuators, including salicylic acid, nicotinamide, and proline, to mitigate the effects of salt stress on nasturtium cultivated in a hydroponic system. The treatments involved different combinations of these compounds under saline conditions (40 mM NaCl). The attenuators reduced the negative impacts of salt stress, promoting improvements in gas exchange, such as increased net photosynthesis, water-use efficiency, and stomatal conductance. Additionally, the treatments enhanced vegetative and reproductive growth, increasing the dry biomass of leaves, stems, and flowers, as well as the number of flowers and flower buds. The combination of salicylic acid, nicotinamide, and proline stood out by providing greater efficiency in carbon assimilation, stability of photosynthetic pigments, and higher tolerance to salt stress. These findings reinforce the potential of using attenuators to optimize the cultivation of nasturtium in saline environments, promoting higher productivity and plant quality.

Inúmeras pesquisas vêm sendo desenvolvidas com intuito de otimizar a produção de hortaliças utilizando resíduos obtidos a partir do processamento de outras matérias primas, destacando a utilização da água residuária da mandioca - manipueira, porquanto apresenta expressiva carga orgânica e nutrientes importantes para o desenvolvimento das plantas. Nesse contexto, o presente trabalho objetivou avaliar o crescimento e produção do coentro cv. Verdão submetido a doses de manipueira, na ausência e presença de esterco bovino. O estudo foi conduzido em casa de vegetação, no delineamento inteiramente casualizado, com os tratamentos distribuídos em esquema fatorial (2x5) com 5 repetições, totalizando 50 unidades experimentais. Os fatores estudados foram: presença (3,9 kg m-2) e ausência de esterco bovino e doses de manipueira (0, 15, 30, 45 e 60 m³ ha-1). Foram utilizados recipientes de plástico com capacidade de 3 dm³, preenchido com solo da camada de 0-0,20 m de um LATOSSOLO AMARELO Ditrocoeso típico. Os maiores rendimentos do coentro foram obtidos com a aplicação de manipueira em conjunto com esterco bovino. A aplicação de 45 m³ ha-1 de manipueira, na presença de esterco bovino, proporcionou maiores área foliar, massa fresca da parte aérea e suculência da parte aérea. Os tratamentos submetidos apenas às diferentes doses de manipueira, na ausência de esterco bovino, apresentaram resposta linear positiva para a maioria das variáveis analisadas, indicando que doses mais elevadas de manipueira poderiam vir a suprimir a demanda nutricional do coentro em substituição ao esterco bovino.

Hydrogen peroxide (H₂O₂) acts as a signaling molecule inducing increased plant tolerance to stress conditions. The objective of the present study was to evaluate the effect of pretreatment with H₂O₂ as a possible attenuator of salt stress on the production of biomass and organic and inorganic solutes in collard greens under salt stress. The plants were grown under hydroponic conditions in a greenhouse. The experimental design used was completely randomized with eight replications with the combination of three times of exposure to H₂O₂ (12, 24, and 36 h) and four levels of H₂O₂ in the pre-treatment solution (0.1, 1.0, 10, and 100 µM). Two control treatments were added, one without the presence of NaCl and another with the presence of 100 mM NaCl, both without pre-treatment with H₂O₂. After 60 days of assay the plants were collected and subsequently analyzed. Salinity affected collard green biomass production regardless of the concentration and time of exposure to H₂O₂. Salinity reduced biomass production in collard greens and there was an increase in Na⁺ and Cl^-, while K⁺ decreased, but pre-treatment with H₂O₂ proved to be effective in increasing the levels of organic solutes, highlighting the importance of H₂O₂ in the plant's adaptive response.