EFFICIENCY OF SOME ESSENTIAL PLANT OILS ON SEWEE DATE PALM FRUIT SPOILAGE CAUSED BY Botrytis cinerea UNDER COLD STORAGE CONDITIONS

Document Type : Original Article

Authors

Plant Pathol. Dept., Fac. Agric., Zagazig Univ., Egypt

Abstract

Date palm (Phoenix dactylifera L.) fruits is considered among the most storage products playing an important role in economic, nutrition and special life in the Arab countries. Fungi are the main source of fruit rots and spoilage, thus reduces their economic value. Seven fungal species were isolated and identified from date fruits cv. Sewee collected at harvesting of Siwa oasis, Egypt, using dilution plate method. The most frequency identified fungi were Botrytis cinerea, Penicillium sp., Aspegillus niger, Alternaria alternata and Fusarium oxysporium, while, Trichoderma sp. and Rhizopus sp. were the lowest detected ones. Washing of date fruits with sterile water decreased the numbers of associated fungi compared with unwashed the control treatment after harvesting (zero time). While pasteurization treatments at 80ºC of Sewee date fruits completely reduced the number of fruits associated fungi followed by pasteurization at 70ºC compared with zero time. Botrytis cinerea Fr. Res was the most frequently isolated fungus causing the highest spoilage incidence on date palm cv. Sewee. Botrytis cinereal, inoculated date fruitsstored under cooled temperature for six months, increased infection and severity percentage. The lowest date fruits infection was recorded after one month, while the highest infection was calculated after the 6th month of cold storage. In vitro experiment revealed that ginger, cinnamon, clove, olive and thyme oils at 5% were the most effective essential plant oils completely inhibiting mycelial growth of B. cinerea, while, anise, sesame and fennel oils were the lowest effective ones. In vivo evaluation of antifungal activities of essential plant oils were recorded on healthy and B. cinerea infected date fruits as a coated treatment. Treatment date fruits with oil highly reduced spoilage caused by B. cinerea for 6 months cold storage period. Ginger, lemon, castor, clove, cinnamon, and olive oils were the most effective onesat 6 months of cold storage period. Generally, date fruits of infection were markedly increased with increasing storage period in oil treated and untreated fruits, as well as in inoculated or un-inoculated fruits. Botrytis cinerea fungal count on inoculated date palm fruits increased significantly with the prolonged storage period for all treatments. Oils coated fruits significantly recorded the lowest fungal count compared to un-treated inoculated ones. Coated date fruits with essential plant oils recorded the highest fruit firmness (FF), reduced the incensement in juice TSS, increased total sugars, markedly decreased tannin contents, and total phenols percentage as increasingcold storage period.

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