Selecting and identifying potential yeast(s) from fruit surfaces microflora against postharvest penicillium rots on citrus.

Includes references.

The yeasts isolated from surface of citrus fruits, harvested from orchards in Behera and Giza governorates were in vitro and in vivo screened for their antagonistic activity against Penicillium digitatum and Penicillium italicum, the causal agents of green and blue molds of citrus. Recovery of sixty-three yeast isolates from citrus fruit surfaces based on morphology of yeast colonies grown on NYDA medium revealed that after further screening, six yeast isolates were recovered from orange (c v. Navel) surface and four isolates from orange (c v. Balady) surface. From on Lemon (Egyptian Limes) surface, seven isolates and from (Common mandarin) surface, six isolates were recovered. The total number of twenty-three obtained isolates after screening showed different levels of antagonistic activity against Penicillium digitatum on NYDA medium in vitro with the greatest effect of Candida tropicalis (ID-11, 20). Evaluation of the biocontrol potential of the yeast antagonists in fruit wounds against green and blue molds caused by Penicillium digitatum and Penicillium italicum on various citrus cultivars was carried out in vivo. Among the twenty-three isolates, recovered from fruit surfaces, fourteen yeast isolates were identified from which seven yeasts i. e. Candida kruisii (ID-2), Trichosporon pullulans (ID 6), Saccharomyces transuaalensis (ID-10), Candida tropicalis (ID-11), Rhodotorula pilimanas (ID-12),Rhodotorula mucilaginosa (ID 17), Candida tropicalis (ID -20) and Sporobolomyces spp (ID-23) in addition to Candida oleophila proved to be the most potential ones in increasing protection levels against Penicillium rots as well as reducing rot area on citrus fruits.

Summary in Arabic.

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