Study of alternative methods, potential resistance inducers, for the postharvest control of the anthracnose (Colletotrichum sp.) in guava fruit

Abstract

One of the factors that may affect guava postharvest quality is the occurrence of rots and anthracnose is the main postharvest disease. Today, there is not fungicides registered for the guava postharvest use and consumers are looking for fruit free of chemical residues. Thus, the objectives of this work will be evaluate the effects of alternative methods (CO2, hot water treatment, UV-C, acetic acid, ethanol, essential oils of lemon grass and pepper, and chitosan) on the postharvest control of guava fruit against anthracnose. Firstly, guava fruit will be inoculated with a conidial suspension of Colletotrichum sp. and after this they will be submitted at the alternative agents applied in different concentrations and methods. The fruit will be stored at 25ºC / 80% RH for 7 days and evaluated for incidence/rot severity and reduction of microbiological contamination. Guava fruit will be also evaluating with regarding physical-chemical (skin and flesh color, firmness, total soluble solids, titratable acidity and vitamin C) and physiological (respiration rate and ethylene production) parameters for the alternative agents that show effective on anthracnose control. Guava fruit will be also inoculated 0, 24, or 48 h after the treatments to check the possibility of resistance induction by alternative agents. According to the results obtained in this experiments the activities of defense related proteins (peroxidase, beta-1,3-glucanase, chitinase, and phenylalanine ammonia-lyase) could be determinate. Mycelial growth and conidial germination will be also evaluated on in vitro assays. The experimental design will be completely randomized and the means values will be submitted at analysis of variance and subsequently compared using the Tukey test at 5% probability level. (AU)