ALTERNATIVAS NO MANEJO DA MANCHA MARROM DE ALTERNARIA E ANÁLISES PÓS-COLHEITA DE TANGERINA ‘DANCY’

Abstract

The 'Dancy' tangerine (Citrus tangerine Hort. ex Tanaka) is susceptible to various diseases, especially of Alternaria brown spot, caused by Alternaria alternata f. sp. citri, which has caused serious damage, preventing the marketing of fruit. Therefore, the aim of this study was to evaluate the potential of the plant extract of Caesalpinia ferrea, Chitosan® and Trichoderma asperellum in control of Alternaria brown spot and postharvest quality 'Dancy' tangerine fruit. The experiment was conducted at the Laboratory of Pathology, Centro de Ciências Agrárias-UFPB, Campus II, Areia-PB. The fruits were purchased from a commercial orchard in the town of Remigio-PB City, then desinfested and immersed in the extract of C. ferrea concentrations: 10; 100; 500 and 1000 µg/mL, Chitosan®: 0.5; 1.0; 1.5 and 2.0g/L. And T. asperellum suspension (1010 conidia/mL). After 24h of application of these products, they were inoculated with A. alternata pathogen (105 conidia/mL) in the 'Dancy' tangerine fruits. After the following evaluations were performed rating: incidence, severity of Alternaria brown spot, weight loss (kg-1), firmness, total soluble solids, titratable acidity, soluble solids/acid ratio, pH and ascorbic acid. The design was completely randomized design with ten treatments and five replications. When used the extract of C. ferrea 'Dancy' tangerine fruit, observed statistical difference, noting that when increased concentrations, increased the incidence and severity of MMA since Chitosan® for the observed inverse to extract behavior. The suspension of the antagonist T. asperellum noted the lowest incidence rates, reduction of A. alternata and the smaller scale of notes to the severity of MMA in relation to all concentrations of C. ferrea, Chitosan® and the witness (ADE). For postharvest assessment, concentrations 10; 100; 500 and 1000 µg/mL of the extract of C. ferrea and 0.5; 1.0; 1.5 and 2.0 g/L of Chitosan®, T. asperellum and the witness (ADE), there was no statistical difference among the treatments for weight loss, fruit firmness, total soluble solids and SST/AT at all concentrations of C. ferrea. Assessed the levels of C. ferrea, Chitosan® and T. asperellum, found that as the concentration increased, increased the titratable acidity, pH, and the rate of ascorbic acid in fruit. Already at concentrations of Chitosan®, found that as the concentration increased, reduced the average ratio for the SST/AT and T. asperellum presented average low for this assessment. And when compared with T. asperellum concentrations 100 g/mL of C. ferrea and 1.5 g/L Chitosan® observed the lowest averages for the rate of ascorbic acid. Therefore, the concentration 100 µg/mL of extract of C. ferrea, 2.0 g/L and T. asperellum, Chitosan® were responsible for reducing the incidence of A. alternata, the severity of MMA and maintain the quality postharvest tangerine fruit 'Dancy'. And the concentrations 10; 500 and 1000 µg/mL of the extract of C. ferrea and 0.5; 1.0 and 1.5 g/L of Chitosan®, were not effective in controlling MMA tangerina fruit 'Dancy', but in some concentrations, retained postharvest qualities 'Dancy' tangerine fruit.