الفهرس 
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Abstract
Pomegranate fruits are one of the most important and valuable fruits all over the world, including Egypt. In recent years, there is high increase of consumer demand of pomegranate due to its high nutritional and medical benefits. The most serious problem with pomegranate is the occurrence of fungal diseases which affected fruits, causing flower loss, premature loss and also resulting in fruit rot in orchards and postharvest storage.
The objectives of this work were to: 1) survey the incidence of fruit rot diseases of pomegranate in some orchards at different governorates, packing houses and cold storage in Egypt; 2) isolation of causal pathogens involved; 3) test various environmentally acceptable control measures to reduce postharvest fruit rot.
Results obtained from this study could be summarized as follows:
1. Different pomegranate orchards, packing house and cold-storage at eight locations from four governorates in Egypt were inspected for surveyed occurrence and frequency of natural infected fruits by associated fungi during 2013 season. High occurrence and frequency of associated fungi isolated from pomegranate fruits were recorded at Manfalout, Tahta, Nubaria, Bani-mazar, Al- Balyana and Assiut, however, Wady El-Natroun and Malawy showed the least occurrence and frequency of natural infected fruits.
2. Isolation of different fungi from naturally infected pomegranate fruits revealed incidence of fungal species associated with these fruits. A total of 286 fungal isolates were collected from samples, which collected from different orchards, packing house and cold- storage at different eight surveyed locations fron four governorates in Egypt. Alternaria spp. was the most frequently isolated fungus with pomegranate fruits, followed by Penecillium spp. and Botrytis sp. Meanwhile, Aspergillus spp., Cladosporium
spp. and Trichoderma spp. were moderate frequently fungi. In the opposite, Epicoccum sp. was the least frequent fungus during season 2013.
3. Fungal isolates belong to seven fungal species were isolated from natural infected pomegranate fruits from calyx and exocarp tissues which collected from different orchards, packing house and cold- storage at different eight locations of four governorates. The most common fungi were identified as Alternaria alternata, Penicillium digitatum and Botrytis cinerea.
4. Pathogenicity test proved that all the most common isolated fungi were pathogenic, with different levels, on pomegranate fruits. Alternaria alternata was the most destructive fungus causing the highest percentage of disease severity, followed by Penicillium digitatum and Botrytis cinerea at 25±1°C determined after 5 and 10 days of inoculation. Whereas, Botrytis cinerea was the most destructive fungus causing the highest percentage of disease severity at 7±1°C determined after 14 and 21 days of inoculation. On the other hand, Penicillium digitatum and Alternaria alternata were the least pathogenic fungi.
5. Effect of hot-water treatments on disease severity of fruit rots of pomegranates was studied. Inoculated fruits with all tested fungi, then immersed in hot water at 52°C for 1, 2 and 3 minutes gave the best efficient results in suppressing the postharvest decay of pomegranate fruits caused by Alternaria alternata, Penicillium digitatum and Botrytis cinerea. In general, hot water treatment at 50 and 52°C for 1, 2 and 3 minutes gave the highest reduction in reducing disease severity for inoculated fruits by all tested fungi in cold storagе stored at 7±1°C and 90% RH for 45 days after inoculation.
6. Effect of different modified atmosphere conditions on linear growth of tested fungi grown on PDA medium, was studied. Carbon dioxide at 15% in air was the most effective concentration
in reducing linear growth of Alternaria alternata, Botrytis cinerea and Penicillium digitatum. While, carbon dioxide at 10% in air gave a moderate effect in reducing the tested fungi linear growth. In contrast, carbon dioxide at 20% in air was the least effective concentration in reducing linear growth for tested fungi grown on PDA medium at 22°C±1 for 7 days in vitro.
7. Effect of different modified atmosphere conditions on rot development, was studied. Inoculated pomegranate fruits held in carbon dioxide at 15% in air showed higher effect in reducing fruit rots caused by Botrytis cinerea, followed by Alternaria alternata and Penicillium digitatum, than carbon dioxide at 10% in air for the same tested fungi. Whereas, inoculated fruits held in carbon dioxide at 20% in air proved to be the least effective in reducing fruits decay in cold storagе at 7±1°C and 90% RH for 45 days after inoculation during the two seasons.
8. Effect of different six salt compounds amended in medium on linear growth for the tested fungi, was studied. Potassium sorbate, followed by Sodium carbonate and Calcium acetate at all four tested concentrations were the highest effective salts in reducing linear growth for all tested fungi. While, Sodium bi-carbonate and calcium lactate at the same concentrations gave a moderate effect in reducing linear growth. In contrast, Calcium chloride at the same concentrations was the least effective salts in reducing linear growth of all tested fungi at 22±1°C for 7 days in vitro.
9. Effect of different salt compounds against disease development, was studied. Inoculated pomegranate fruits immersed in Potassium sorbate and Calcium acetate at all their three tested concentrations were the highest effective salts in reducing severity of infection during the two seasons. Also, Sodium bi-carbonate gave a great efficacy against disease development during second season at the same concentrations, however Sodium bi-carbonate and Sodium carbonate gave a moderate efficacy in reducing
disease development. In the opposite, Calcium lactate and Calcium chloride gave the least efficacy at the same concentrations in cold storagе at 7°C±1 and 90% RH for 45 days after inoculation during the two seasons.
10. Effect of some organic acids to reduce linear growth of the tested fungi amended in medium, was studied. Acetic acid and Jasmonic acid at all four investigated concentrations were the highest effective organic acids in reducing linear growth for all tested fungi at 22°C±1 for 7 days in vitro. In contrast, Salicylic acid at the same concentrations was the least effective in reducing linear growth of all tested fungi at the same concentrations.
11. Effect of some organic acids to reduce decay development, was studied. Inoculated pomegranate fruits immersed in Acetic acid and Jasmonic acid at all concentrations gave a highest efficacy to reduce disease development on pomegranate fruits which inoculated with the tested fungi. Meanwhile, Salicylic acid at the same concentrations was the least effective organic acid in reducing severity of infection in cold storagе at 7°C±1 and 90% RH for 45 days after inoculation during the two seasons.