الفهرس 
Materials and methodsOnly 14 pages are availabe for public view
 |  | from | 231 |  |  |
| | | from | 231 | | |
Abstract
A field survey was conducted in four governorates of Egypt to gain more information about the importance of Orobanche spp. in faba bean and winter tomato cropping and to learn knowledge, perceptions, control strategies and difficulties concerning the parasitic weed and to be able to evaluate the possibilities to integrate a potential mycoherbicide into the farming systems. Some cultural methods like rotation with clover, flood irrigation and nitrogen fertilization that are regularly applied by almost all farmers may contribute to the low infestation level in all regions. Orobanche shoots showing symptoms of a fungal disease were collected and the potential fungal antagonists were isolated out of these plants and screened for pathogenicity against Orobanche under controlled environmental conditions. Only two isolates classified as Fusarium oxysporum maintained an ability to cause disease symptoms on O. crenata and O. ramosa shoots. The results of pots experiment indicate that Orobanche reduced growth parameters of host plants and also photosynthetic pigments, carbohydrates, protein and AsA content. On the other hand, infestation resulted in inhibitions of CAT, POD and GST activities. On the contrary, these were great inductions in anthocyanin H2O2 accumulation as well as activities of PAL, TAL, CI and SOD. Pesta applications raised growth parameters of Orobancheinfested plants to mostly reach control. Similar increase were also detected in photosynthetic pigments, carbohydrates, protein and AsA as well as in activities of SOD, CAT, POD and GST. However, retractions of the enhanced anthocyanin, H2O2 and activities of PAL, TAL, CI and SOD were set in. Therefore, it could be concluded from the present results that both faba bean and tomato are susceptible to Orobanche infestation. This conclusion of susceptibility is based upon the great reduction in growth parameters of both hosts. Orobanche in the fields of these susceptible lines of faba bean and tomato could be controlled by application of Fusarium oxysporum isolates in palletized Pesta formulations. Further confirmation of susceptibility came from the changes in the internal biochemical parameters. Indeed, activities of CAT, POD and GST increased giving rise to accelerate the detoxification of H2O2. Therefore, H2O2 accumulation seemed to be retracted beyond it toxic level that might come from increased SOD activity and decreased activities of CAT, POD and GST. Moreover, AsA was recovered upon Pesta application to meet the plant needs for ascorbateglutathione cycle for antioxidative defense mechanism. Such application could therefore improve the antioxidative system. For these characterizes together of the Pesta formulation at 1.25 g/kg soil which selectively destroyed Orobanche without harmful effect to the host plants, it could be recommended to use these formulations as bioherbicides to control Orobanche in faba bean and tomato fields.