Efficacy of Gibberellic Acid in Controlling Pathological Decay and Maintaining Post-Harvets Quality of Passion Fruits (Passiflora edulis var. edulis sims.)

Abstract

Pathogens cause deterioration of passion fiuits and resist pesticides applied post-harvest to control them. Pesticides, unlike most plant growth regulators, may pose a health hazard to consumers. This research aimed at determining the effect of gibberellic acid (GA3) and timing of application on the post-harvest quality of passion fruits inoculated with Penicillium expansum and stored in a room maintained at 17 to 22° C and over 85 % relative humidity for 48 hours. Fruits were sprayed with 0, 50, 100, or 250 ppm GA;, packed in clear polythene bags and kept at room temperature. Repeated data were recorded at 2- days interval for 20 days post-treatment. Early application of GA; significantly maintained soluble solids, colour, fimmess, chlorophyll, and weight, and slowed disease incidence and severity, fruit loss, and ethylene evolution. Application of GA; at 0 days post-harvest (dph) was more effective in delaying deterioration than application at 5, 10, or 15 dph. Gibberellic acid significantly inhibited disease incidence, fruit loss, and ethylene evolution frequently, whereas it significantly affected colom, soluble solids, chlorophyll, and firmness occasionally. Weight and disease severity were least aflected by GA;. The effects of 50, 100, and 250 ppm GA; were similar, but greater than of 0 ppm GA;. In a related experiment, passion fruits were stored for 0, 5, 10, or 15 dph before fungi were isolated on a potato dextrose agar medium to determine the effect of storage time on prevalence. P. expansum, F usarium oxysporum, Alternaria passiflorae, Seploria sp., Cladusparium sp., Aspergillusflavus, and Rhizopus stolonifer were isolated. Prevalence increased with storage time. This research revealed that passion fruits should be treated with preservatives soon after harvest, because delaying renders the fi'uits susceptible to post-harvest pathogens. lll