Ripening of ‘Kumagai’ guavas and anthracnose control as affected by methyl jasmonate

ABSTRACT

Methyl jasmonate (MJ) is an endogenous regulator that can influence fruit ripening and the defense system against pathogens. This work verified the influence of this regulator on postharvest physiology, control of anthracnose and physicalchemical attributes of ‘Kumagai’ guava (Psidium guajava L.). Guavas harvested at mature-green and ripe stages were treated with 0, 1 and 10 μmol∙L⁻¹ MJ as gas in hermetic containers (200 L) with air circulation for 24 h. Fruit were inoculated with Colletotrichum gloeosporioides spore suspension (10⁵ spores∙mL⁻¹) 24 and 48 h after treatment. During ripening, at 25 °C and 80 – 90% of relative humidity, respiration, ethylene production, anthracnose incidence, severity and quality of guavas were assayed. Data were subjected to analysis of variance and means, compared by Tukey’s test (p ≤ 0.05 and 0.10). The application of 1 and 10 μmol∙L⁻¹ MJ had little influence on ripening of ‘Kumagai’ guava with a slight increase in respiration, ethylene production and yellowing of fruit harvested at ripe stage. Treatments with 1 and 10 μmol∙L⁻¹ MJ did not reduce the severity and incidence of C. gloeosporioides when applied in fruit harvested at ripe and mature-green stages and inoculated 24 or 48 h after MJ treatment. In conclusion, the MJ treatment, at 1 and 10 μmol∙L⁻¹ concentrations, had little influence on ripening and did not control anthracnose in ‘Kumagai’ guavas.

Key words
Colletotrichum gloeosporioides; Psidium guajava L.; growth regulator