ABSTRACT. This study aimed to investigate the potential of rhizobacteria isolated from tomato plants to control Sclerotinia sclerotiorum and induce the activity of pathogenesis-related enzymes in Micro-Tom tomato plants. Three rhizobacterial isolates were evaluated to determine the most efficient antagonist agent, which was later identified by gene sequencing as Bacillus amyloliquefaciens PKM16. The antagonistic effects of B. amyloliquefaciens against S. sclerotiorum were assessed in vivo and in vitro using live and autoclaved cultures at concentrations of 0% (control), 20%, 30%, and 40% (v/v). The residual effects of four treatments (20% live culture, 20% autoclaved culture, a Bacillus subtilis-based commercial product, and autoclaved distilled water) on tomato plants inoculated with S. sclerotiorum were determined. The same treatments were also used to assess the myceliogenic germination of sclerotia and induction of plant defense enzymes (peroxidase, catalase, polyphenol oxidase, phenylalanine ammonia-lyase, and β-1,3-glucanase) in tomato plants. The live culture had a residual effect for 4 days and inhibited sclerotial germination by approximately 30%. Furthermore, live and autoclaved bacterial growth cultures stimulated enzyme activity. Therefore, B. amyloliquefaciens PKM16 was antagonistic to S. sclerotiorum, effectively inhibiting mycelial growth and activating defense mechanisms in Micro-Tom tomato plants.

O objetivo da pesquisa foi avaliar a efetividade da quitosana e da embalagem de polietileno associada à refrigeração na qualidade da mandioquinha-salsa cv. Amarela de Senador Amaral. Os tratamentos realizados foram: aplicação de quitosana a 1,5%; embalagem de polietileno revestida com filme de PVC e controle (não-tratado e com embalagem plástica). As mandioquinhas-salsa foram lavadas, descascadas, sanitizadas e tratadas e em seguida foram armazenadas a 0 ºC durante 18 dias e a 5 ºC sendo conservada por 9 dias, ambos com 95% UR. O experimento foi disposto em esquema fatorial 2 x 7 x 2 (2 tratamentos x 7 períodos x 2 temperaturas) com 5 repetições, cada uma composta por 5 tubérculos de mandioquinhas-salsa. As avaliações químicas realizadas foram: determinação dos teores de sólidos solúveis, açúcares totais, amido, atividade enzimática da polifenoloxidase e da peroxidase. A quitosana promoveu efeito elicitor de respostas bioquímicas da defesa da mandioquinha-salsa, com aumento significativo nas atividades da polifenoloxidase e da peroxidase.

The aim of this research was to evaluate the effectiveness of chitosan and polyethylene packaging, associated with refrigeration, on the quality of the arracacha cv. Amarela de Senador Amaral. The treatments carried out were, application of 1.5% chitosan, polyethylene packaging lined with PVC film, and a control (untreated and in plastic packaging). The arracacha were washed, peeled, sanitised and treated, and then stored at 0 °C for 18 days and at 5 °C for 9 days, both at 95% RH. The experiment was arranged in a 2 x 7 x 2 factorial (2 treatments x 7 periods x 2 temperatures) with 5 replications, each consisting of 5 arracacha tubers. The chemical evaluations performed were: determination of the levels of soluble solids, total sugars, starch and the enzymatic activity of polyphenoloxidase and peroxidase. The chitosan promoted an elicitor effect of biochemical responses in the defences of the arracacha, with a significant increase in the activities of polyphenol oxidase and peroxidase.