DUAL MODE OF ACTION OF ETHANOLIC EXTRACT OF PROPOLIS (EEP) FOR THE CONTROL OF POSTHARVEST ANTHRACNOSE IN DRAGON FRUITS

The in vitro and in vivo study was conducted to evaluate the potential of ethanolic extract of propolis (EEP) against postharvest anthracnose of dragon fruits caused by Colletotrichum gloeosporioides. Four different concentrations (0.25, 0.5, 0.75 and 1.0%) of EEP along with untreated control were used during the study. All EEP treatments showed a significant (P<0.05) decrease in mycelial growth and conidial germination. EEP concentrations at 0.5, 0.75 and 1.0% gave the most promising results and more than 60% inhibition in radial mycelial growth and conidial germination was observed. EEP treatments slowed down the onset of disease symptoms resulting in a delay of disease development and maintaining quality. Induction of anthracnose resistance was also studied in relation with the enhanced activation of inducible compounds [peroxidase (POD), polyphenol oxidase (PPO), and phenylalanine ammonia lyase (PAL)]. An increase in activity of these enzymes was recorded at 0.5, 0.75 and 1.0% EEP concentrations. But some phytotoxic effects were observed on fruits treated with higher concentrations of EEP (0.75 and 1.0%). Thus, it can be concluded that 0.5% of EEP concentration can be used for the management of postharvest anthracnose in dragon fruits.