Strobilurins are fungicides with beneficial physiological effects on crop yield due to promotion of net carbon assimilation, nitrate reductase enzyme activity, stress tolerance and hormonal balance. The carboxamides complement the action of the strobilurins when applied alternately or together. This study aimed to evaluate the effect of application of pyraclostrobin, azoxystrobin and boscalid on grafted and ungrafted Japanese cucumber (Cucumis sativus L.) in order to analyze the effects of these fungicides on plant physiology and increased fruit production. The experimental design was completely randomized in a 2 × 5 factorial scheme, with grafted and ungrafted cucumber plants and 5 fungicide treatments: control; azoxystrobin 60 g a.i ha −1 ; boscalid 50 g a.i ha −1 ; pyraclostrobin 50 g a.i ha −1 ; and boscalid 100 g a.i ha −1 + pyraclostrobin 50 g a.i ha −1 , applied 18 days after transplanting and then at intervals of seven days. The effect of the treatments was evaluated based on the average yield and fruit mass, in addition to observations of gas exchange, lipid peroxidation, and the activities of peroxidase, superoxide dismutase, catalase and nitrate reductase. Based on the results obtained, it was concluded that the fungicide treatments resulted in different responses between the grafted and ungrafted plants. The physiological benefits were more evident in the grafted plants treated with pyraclostrobin or boscalid alone, and these benefits manifested in terms of fruit production and increased the activity of the antioxidative system, thereby reducing stress. The higher productivity probably occurred due to the better physiological performance of these plants, mainly at the beginning of development, presenting greater activity of the enzyme nitrate reductase, in addition to the higher net CO 2 assimilation and carboxylation efficiency.

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ResumoO trabalho avaliou o efeito de estrobilurinas, boscalida, reguladores e extratos vegetais na qualidade físico-química de frutos de tomateiro (Solanum lycopersicum L.), híbrido Giuliana. Os frutos de cada tratamento foram selecionados e separados em 4 repetições: testemunha, piraclostrobina, boscalida, piraclostrobina + boscalida, IBA + GA 3 + cinetina, GA 4+7 + benzilaminopurina e extrato vegetal. A primeira aplicação foi realizada 30 dias após o transplantio e as demais, a cada 15 dias. As avaliações foram: perda de massa, acidez titulável (AT), sólidos solúveis (SS), relação SS/AT, pH, teor de ácido ascórbico, textura, açúcares solúveis totais (AST), atividade da pectinametilesterase (PME) e poligalacturonase (PG). O teor de SS, responsável pelo sabor do fruto, variou em função dos tratamentos, sendo o maior para GA 4+7 + benzilaminopurina e o menor para a testemunha. O mesmo aconteceu com a relação SS/AT. Os frutos permaneceram por 9 dias em bancada, em temperatura ambiente e ao final desse tempo, alguns tratamentos ainda apresentavam frutos ótimos para o consumo, destacandose o tratamento com boscalida, que apresentou menor perda de massa, seguido pela piraclostrobina. Assim, pode-se concluir que a aplicação dos tratamentos não alterou os valores de pH, AT e AST dos frutos. Notou-se maior atividade da PME nos tratamentos com boscalida e com a mistura de boscalida e piraclostrobina, ao mesmo tempo, se constatou menor atividade da PG nos tratamentos testemunha e piraclostrobina, indicando que alguns produtos aceleraram o processo de desmetilação das pectinas pela PME, facilitando a ação da PG. Palavras-chave: Solanum lycopersicum, estrobilurinas, boscalida, reguladores vegetais, pós-colheita AbstractThe present work evaluated the effect of strobilurins, boscalid, plant growth regulators and vegetal extracts on the physico-chemical quality of tomato fruits (Solanum lycopersicum L.), hybrid Giuliana. The fruits from each treatment were selected and separated in 4 repetitions: control, pyraclostrobin, boscalid, pyraclostrobin + boscalid, IBA + GA 3 + kinetin, GA 4+7 + benzylaminopurine and vegetal extract. The first application was carried out at 30 days after transplant and the following at every 15 days. The evaluations were: weight loss, titratable acidity (TA), soluble solids (SS), SS/TA relation, pH, ascorbic acid content, texture, total soluble sugars (TSS), activity of pectin methyl esterase (PME) and polygalacturonase (PG). The SS content, responsible for fruit flavor, varied accordingly to the treatment, being highest for GA 4+7 + benzylaminopurine and lowest for the control. The same occurred regarding the SS/AT relation. The fruits were kept on the shelf for 9 days, at room temperature, being that at the end of this period several treatments still presented fruit in optimal consumption conditions, notably the boscalid treatment, which presented lowest weight loss, followed by pyraclostrobin. Therefore, it can be concluded that the application of the treatments did not modify the values for pH, AT...

ResumoEste trabalho teve como objetivo estudar os efeitos fisiológicos da piraclostrobina, boscalida, reguladores vegetais e extrato vegetal no acúmulo de carboidratos durante o desenvolvimento de plantas de tomateiro (Solanum lycopersicum L.), híbrido Giuliana, em condições de ambiente protegido. Os tratamentos estudados foram: T1-testemunha; T2-piraclostrobina 0,2 g L-1 e T7-extrato vegetal 100 mg L -1 . A curva de acúmulo de carboidratos foi realizada com cinco amostras, em intervalos de 20 dias entre as avaliações, sendo a 1ª avaliação realizada aos 30 dias após o transplantio, no dia da primeira aplicação dos tratamentos. A cada coleta as plantas foram separadas em caule, folha e frutos, nos quais foram avaliados os teores de açúcares solúveis totais, açúcares redutores e sacarose. Também foram avaliados os efeitos dos tratamentos no teor de clorofila e nas trocas gasosas. O delineamento experimental adotado foi inteiramente casualizado, com quatro repetições e seis avaliações destrutivas ao longo do desenvolvimento, sendo uma planta por unidade experimental em cada amostragem. A piraclostrobina e a boscalida aplicados isolados e/ou combinados favoreceram o incremento de carboidratos nas folhas, caules e frutos de tomate 'Giuliana'. Palavras-chave: Solanum lycopersicum L., estrobirulina, piraclostrobina, boscalida, trocas gasosas AbstractThis work had the purpose to study the physiological effects of pyraclostrobin, boscalid, plant growth regulators and plant extract on the accumulation of carbohydrates during the development of tomato plants (Solanum lycopersicum L.), hybrid Giuliana, in protected environment conditions. The treatments were:+ benzylaminopurine 100 mg L -1 and T7-plant extract 100 mg L -1 . The carbohydrate accumulation curve was accomplished with 5 samples, at 20-day intervals between evaluations, the 1 st evaluation being carried out at 30 days after transplantation, on the day of the first treatment application. At each sampling the plants were separated in stem, leaves and fruits, of which the contents of total soluble sugars, reducing sugars and saccharose were evaluated. The effects of the treatments on chlorophyll content and gas exchanges were also evaluated. The experimental design was completely randomized, with 4 repetitions and 6 destructive evaluations during the development, with 1 plant per experimental unit for each sampling. The pyraclostrobin and boscalid applied in isolation and/or combined favor the increase of carbohydrates in leaves, stems and fruits of tomato hybrid Giuliana.