الفهرس 
Adverse effects of Fusarium on tomato plantsOnly 14 pages are availabe for public view
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Abstract
Fusarium wilt disease is one of the major plant diseases that affect the production of tomato and many other crops. In the present investigation natural plant aqueous extracts -#102;-#114;-#111;-#109; neem (Azadirachta indica) and willow (Salix babylonica) were used to control fusarium wilt. Also, nonpathogenic Fusarium oxysoprum f.sp dianthi (NPF) and Pseudomonas fluorescences were applied to protect tomato -#102;-#114;-#111;-#109; fusarium wilt. The results indicated that the percentage of disease incidence were increased in non treated tomato seedlings in a time dependent manner and reached the maximum level (65%) after 6 weeks of infection. Treatment of tomato plant with 10% neem extract, 10% willow extract, NPF and Pseudomonas fluorescences reduced the percentage of disease incidence to the level of 25.5, 27.8, 36.9 and 28.2% respectively. Infection of tomato seedlings with Fusarium oxysporum led to reduced shoot and root growth. Both natural extracts, NPF and Pseudomonas fluorescences improved tomato growth under infection or non infection conditions. br The results clearly indicated that infection of tomato seedlings with Fusarium oxysporum led to a high level of lipid peroxidation -#119;-#104;-#101;-#114;-#101; the level of malondialdehyde (MDA) in plant tissue was increased about two times after 3 and 7 days of infection. Pretreatment of tomato seedlings with neem extract, willow extract, NPF and Pseudomonas fluorescences protected tomato -#102;-#114;-#111;-#109; oxidative stress induced by Fusarium oxysporum. br Phenolic compounds were increased in tomato seedlings by treatment with neem extract, willow extract, NPF and Pseudomonas fluorescences compared to infected untreated seedlings. Also increase of proline content in infected groups treated with neem extract, NPF and Pseudomonas fluorescence was noticed. br The observed accumulation of phenols was explained by increasing the activity of phenylalanine ammonia-lyase (PAL) in tomato seedlings treated with neem extract, willow extract, NPF and Pseudomonas fluorescences and in infected tomato seedlings. Also these natural extracts and biological agents caused significant elevation in polyphenol oxidase (PPO) activity. Inoculation causes a significant increase in the antioxidant defensive enzymes i.e. peroxidase (POX), catalase (CAT) and superoxide dismutase (SOD). The high levels of antioxidant enzyme in infected tomato seedlings were not associated with an inhibition of lipid peroxidation as expressed by the level of MDA. br Treatment of tomato seedlings with neem extract, willow extract, NPF and Pseudomonas fluorescences induced high activities of POX, CAT and SOD after 3 and 7 days of infection. Peroxidase isozymes separation indicated that infection of tomato seedlings with Fusarium oxysporum led to induction of many POX isoforms. br In addition treatment of tomato seedlings by neem extract, willow extract, NPF and Pseudomonas fluorescences resulted in appearance of new POX isozymes and a considerable change in POX genes expression. br The results concluded that neem extract, willow extract, NPF and Pseudomonas fluorescences were able to reduce the disease incidence of Fusarium wilt through reduction of lipid peroxidation and induction of antioxidant enzymes as well as phenol biosynthesis enzyme PAL.