الفهرس 
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Abstract
47 isolates of fruits were purified from postharvest fruits such as mango, dates, pomegranate, lemon, banana, and grapes) and vegetables including garlic, tomatoes, potatoes, eggplant, onion, watermelon, okra, and pepper. After calculating the percentage of isolates, we confirmed that the most isolates were Penicillium, Alternaria, and Aspergillus, then the genus Botrytis and Fusarium, while Rhizopus was the least isolated. Effect on mycelial growth Salicylic acid (SA) has a very high inhibitory effect on the tested fungi, especially at the concentration of 14 mM. Moreover, the concentration of 14 mM caused a higher value of the reduction in P. digitatum and A. alternata growth. NO significantly inhibited the mycelial growth of S. sclerotiorum at concentrations of 10, 12, 14, and 16 mM. Mycelial growth was completely inhibited at the concentration of 16 mM. The mycelial growth of B. cinerea was significantly prevented by Si at all concentrations. The concentration of 16 mM of Si caused a strong inhibition of the fungal growth by 94.81%. OA showed significant activity and inhibited the mycelial growth of F. sambucinum in a dose-dependent manner. The percentage inhibition of mycelial growth values ranged from 51.11 to 96.42% at concentrations of 10 and 16 mM, respectively. SA significantly showed inhibition on the spore germination of P. digitatum at all concentrations. P. digitatum spore germination was extremely inhibited by 94.80% at the concentration of 16 mM. The concentration of 16 mM from NO exhibited strong inhibition effects on spore germination of F. sambucinum, P. digitatum, A. alternata, A. niger, A. flavus, and A. parasiticus. Effect on spore germination P. digitatum spore germination was extremely inhibited by 94.80% at the concentration of 16 mM from SA, with 92.25% inhibition at 14 mM. The concentration of 16 mM from NO exhibited strong inhibition effects on spore germination of F. sambucinum, P. digitatum, A. alternata, A. niger, A. flavus, and A. parasiticus. The concentrations of 14, and 16 mM from Si exhibited a remarkable inhibition effect on the spore germination of B. cinerea by 92.73 and 96.34%, respectively. OA caused a strong antifungal effect against F. sambucinum (94.56% inhibition) at the concentration of 16 mM. Effect on myceliogenic germination of sclerotia The concentration of 16 mM from NO-induced the greatest inhibition of myceliogenic germination of S. sclerotiorum sclerotia by 97.71% Development of fruit molds Application of SA at the concentration of 16 mM caused the maximum decrease in both disease incidence and disease severity by 55 and 59.06%, respectively, in orange fruit inoculated with P. digitatum. All concentrations of NO significantly decreased the incidence and severity of postharvest carrot rot caused by S. sclerotiorum. Disease incidence in the Si-treated fruit at 16 mM was 65.58% lower than that in the untreated fruit, and the disease severity was lower than that in the control by 78.58%. SA caused a significant reduction in both incidence and severity of tomato black rot at all concentrations compared with the control. The treatment of OA at the concentration of 16 mM reduced the severity of dry rot in potato tubers inoculated with F. sambucinum by 75.36%. Measurement of defense-related enzyme activity and total phenol PPO and POD activity was induced in the orange fruit treated with SA at the concentration of 12 mM throughout storage in comparison to the control as well as the total phenolics. The carrot treated with NO at 16 mM was higher in the activity of POD, PPO, and content of total phenols than untreated fruit during storage. The POD and PPO activity with the total phenols in the grape treated with Si at 16 mM was higher than that of the control during four days of the storage period. POD and PPO were enhanced in SA-treated tomato fruit during the whole experiment. The total phenolics were increased throughout the experiment compared with the control treatment. POD activity in potato tubers treated with OA showed a great increase compared with the control as well as the PPO activity. Potato tubers treated with OA on the fourth day of exposure showed the highest level of total phenolics.