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Seaweed extracts have several functions in agriculture due to their composition that is rich in nutrients, plant hormones, and bioactive substances. It is a natural product used as a biostimulant especially to promote the growth and development of plants and their tolerance to environmental stresses. The objective of this study was to analyze the response to a biostimulant containing seaweed extract derived from Ascophyllum nodosum in the cultivation of tomato and eggplant seedlings, analyzing the growth and physiological parameters in two different regions of Brazil. Cherry tomato and eggplant were cultivated in polyethylene trays for 30 days. In each crop, five treatments were tested, comparing the use of a commercial seaweed extract in application doses and forms, which were the control (without seaweed application); 0.1%, 0.2%, and 0.3% of the seaweed extract applied by irrigation water; and treatment with 0.2% of the seaweed extract by foliar application. This study confirms the efficacy of incorporating seaweed extract from Ascophyllum nodosum as a bio-input into the production phase of Solanaceae seedlings. The seedlings which received the seaweed extract significantly increased some morphological parameters, mainly regarding the biomass and length of leaves, stems, and roots. In general, applying both methods through irrigation water and foliar application were effective in providing benefits compared to the control treatment. The intermediate dose (0.2%) was the most effective in promoting improvement in the analyzed parameters. This underscores the importance of obtaining quality seedlings for subsequent planting in the field, potentially leading to better acclimatization and initial adaptation.

Water management has a direct impact on plant development, and under deficit conditions, it often results in reduced yields. Silicon (Si), however, has the potential to alleviate stress and enhance plant performance under unfavorable conditions. This study aimed to analyze the performance of tomato plants cultivated under different water replacement depths and forms of silicon application. The experiment was laid out in a completely randomized design with a 2 × 4 factorial arrangement represented by two water replacement depths (60% and 100% of crop evapotranspiration - ETc) and four forms of silicon application (without application, soil application - full dose, soil application - split dose, and foliar applications). Four replications were used. The plants were cultivated in a protected environment using drip irrigation for water replacement, and silicon oxide served as the source of the element. The analyzed parameters included daily evapotranspiration, leaf spectral reflectance, mass accumulation (root, stem, and leaf), yield indices (fruit weight, plant yield, and defective fruits), water productivity, and post-harvest fruit weight loss. The imposition of water deficit (60% of ETc) in tomato leads to reduced crop development and yield, with the effects partially mitigated by the application of silicon. Conversely, under conditions of adequate water replacement (100% of ETc), silicon application contributes to increased development and yield of tomato. The application of silicon in the soil, whether in a full or split dose, demonstrates a more favorable response in vegetative indices and yield for tomato.

ABSTRACT The application of silicon (Si) in plants benefits the performance of several species. However, the dynamics of the element, mainly in non-accumulating species such as tomatoes, are rarely analyzed. This study investigated the dynamics of Si in tomato plants cultivated under different forms of application and water conditions. The experiment was carried out in a completely randomized design with four replications, using a factorial scheme 2 x 4: two water conditions (60 and 100% of the evapotranspiration of the crop - ETc), and four forms of silicon application (without application, full dose applied at soil, split dose applied at soil, and foliar application). Si content in the soil and in the different plant organs were analyzed. Si content in the soil increased after the crop cycle depending on the application form (full or split doses). The dynamics of Si accumulation and extraction by tomato are influenced by the application form (higher in soil application) and water management, with fruits and leaves having the higher values. Si application, mainly in the soil, increased the rate of Si accumulation and extraction by tomatoes cultivated in different water conditions.

Deficit irrigation is applied to several agricultural crops as a water-saving irrigation strategy. The tomato plant is sensitive to water stress; however, integration with biostimulant applications, based on seaweed extracts, could be a strategy for plants adapting to this abiotic condition. The objective of this study was to evaluate agronomic and quality aspects of tomato cultivated under deficit irrigation combined with Ascophyllum nodosum extract (ANE) application. The experiment was conducted using a completely randomized design with two water replacement levels, 70 and 100% of crop evapotranspiration (ETc), and five doses of ANE (0, 0.1, 0.2, 0.3 and 0.4%) applied via soil drench. The interaction between ANE and ETc was significant (p < 0.05) in terms of plant growth, physiological parameters, fruit yield, yield components and fruit quality. Results indicated that when the tomato plant is under deficit irrigation, a higher ANE dose is required to achieve better development when compared to the 100% ETc condition, where the dose is lower. Under deficit irrigation, the largest fruit yield was obtained with 0.3 and 0.4% ANE, and with 100% ETc, the largest fruit yield was obtained with 0.2% ANE. ANE applications were also effective in increasing plant height, stem diameter, plant biomass, leaf area, chlorophyll and relative water content. In addition, tomato quality was also favored under deficit irrigation and seaweed extract application. We conclude that ANE applications attenuate water deficit effects in tomato plants and provide a strategy to ameliorate tomato yield, tomato quality and water use in agriculture.

A clorofila, molécula responsável pela atividade fotossintética das plantas, pode ser quantificada por métodos diretos e indiretos. O objetivo do estudo foi relacionar os resultados do conteúdo de clorofila obtidos por diferentes métodos de determinação em folhas de quiabo. Foi estimado o conteúdo de clorofila através do índice SPAD (não-destrutivo) e da extração dos pigmentos foliares com acetona (destrutivo). As análises foram realizadas em folhas de quiabo (cultivar Santa Cruz 47) do terço médio de plantas no estágio reprodutivo com coloração variando de amarela a verde escuro, em condição de sequeiro. Determinações pelo método não destrutivo foram realizadas com equipamento SPAD-502 e as determinações por método destrutivo foram realizadas por espectrometria, utilizando acetona como extrator. Foi realizada análise descritiva, correlação e regressão nos dados. O índice SPAD variou de 20,93 a 49,03, e apresentou correlação linear com o conteúdo de pigmentos foliares. O índice SPAD apresentou correlação positiva com os teores de clorofila b e clorofila total, entretanto para o conteúdo de clorofila a foi observado relação negativa. A variação do conteúdo de carotenoides não apresentou relação direta com o índice SPAD. A estimativa do conteúdo de clorofila por método não destrutivo apresenta relação direta com o conteúdo absoluto em folhas de quiabo.