Termoterapia no manejo da antracnose e conservação pós-colheita da banana "Prata-Anã"

Abstract

Thermotherapy can directly control plant pathogens and activate defense mechanisms of the fruit. Thus, the study aimed to evaluate the use of thermotherapy in the management of anthracnose and postharvest conservation of "Prata-Ana" banana produced in the North of Minas Gerais. Bunches of bananas were sprayed with the suspension of Colletotrichum musae spore and immersed in water at 40, 44, 48, 52 and 56 °C for 4, 8, 12 and 16 minutes. The controls constituted of fruit immersed in water at 20 °C with and without inoculation of the fungus. The bunches were stored at 25 ± 1 °C and 80 ± 5% RH, analyzed as for the incidence and severity of injury for 15 days every three days, in a total of five evaluations. The design entirely at random in a 5 x4 x5 + 2 factorial. Data were subjected to analysis of variance and Scott-Knott test (P<0.05). Controls were subjected to Dunnett test (P<0.05). The thermotherapy evaluation associated with chemical control was performed by immersion of the fruits at 52 °C for 8 minutes. Part of the treated fruits was sprayed with fungicide Imazalil. The treatments consisted of fruits submitted to thermotherapy with or without fungicide application, being the controls the fruits without thermotherapy with and without fungicide application. The fruits were stored at 25 ± 1 °C and 80 ± 5% RH in a randomized design. Data were subjected to analysis of variance and compared by F test, and the controls compared to treatments by Dunnett's test (P<0.05). The evaluation of the physical and chemical characteristics of the fruits was by means of treated fruits at 52 °C for 8 minutes and stored at 9, 11, 13 and 15 °C. The evaluations were performed every five days for 30 days. The design was at random with a 4 x 6 factorial, and the data subjected to analysis of variance and regression. The thermotherapy at 52 °C for 8 minutes immersion reduced the severity of anthracnose on fruits from 29.66% to 3.58%. The temperature of 56 °C damaged the fruits causing greater disease severity. Combination of thermotherapy/chemical treatment was effective for managing anthracnose disease with decrease of 20,99%. The use of thermotherapy in "Prata-Ana" banana with low density polyethylene package allowed a period of 30 days of storage at 13 °C with adequate maintenance of firmness, color, content of soluble solids, acidity and pH. Thermotherapy applied in "Prata-Ana" banana in post-harvest proved to be efficient in the management of anthracnose and preserved the physical and chemical characteristics of the fruits.