ISOLATION AND DETERMINATION OF SOME HARMFUL MOLDS ON POST-HARVESTED DRAGON FRUIT PEELS Hylocereus costaricensis

Abstract

The dragon fruit is a fruit with high nutritional, economic value for Vietnam but it has a short shelf life. Harmful mold is one of the causes of post-harvest quality loss of dragon fruit. This study was conducted to find out harmful mold strains on the dragon fruit peel Hylocereus costaricensis during post-harvested storage. By inoculating nine damaged peel samples of the dragon fruit H. costaricensis from a dragon fruit garden in Long An province on the selective agar media Czapeck-Dox, five mold strains were isolated and purified. Basing on the macroscopic (colony morphology) and microscopic (cell morphology observed by light microscope) characteristics, strains N1 and N2 could belong to genus Fusarium, strain N3 could belong to genus Neoscytalidium, strain N4 could belong to the genus Rhizopus and strain N5 could belong to the genus Aspergillus. Two mold strains N1 and N3 were further identified as Fusarium fujikuroi (100% similarity) and Neoscytalidium sp. (100% similarity) by sequence analyses of ITS and LSU regions of rRNA gene in combination with morphological characteristics, respectively. The artificial infection examination showed that both F. fujikuroi N1 and Neoscytalidium dimidiatum N3 strains caused the damages on fruits after harvest. The obtained results of this study provided more data of harmful molds, thereby helping to guide the prevention and preservation of post-harvested dragon fruit Hylocereus costaricensis in Viet Nam.