الفهرس 
CONTENTSOnly 14 pages are availabe for public view
 |  | from | 101 |  |  |
| | | from | 101 | | |
Abstract
Seed health testing and survey for fungi associated with sugar beet seeds: Deep-freezing blotter method was used on 15 sugar beet varieties. The results showed that Fusarium moniliforme was the most frequent fungus associated with sugar beet seeds of most varieties. Isolates of F. moniliforme were purified using hyphal tip technique. Pure cultures of all isolates were used to fulfill Koch’s postulates. All isolates were pathogenic and caused damping off with various degrees of disease severity. The most virulent isolate was used for further studies. 2. In vitro experiment : By using alternative friendly chemicals and biological control agents to control soil and seed born fungi attacking sugar beet crop. Nicotinic acid (1mM, 5mM, 10mM, 15mM and 20mM), potassium silicate (4ml/L, 6ml/L, 8ml/L, 10ml/L and 12ml/L), T. harzianum, T. hamatum, B. subtilis were tested in comparison with the fungicide Maxim® (143ml/L). All treatments caused growth inhibition to. moniliforme colonies on PDA medium. 3. In vivo experiments : 3.1. In the greenhouse: Sugar beet seeds were soaked in the most effective concentrations/treatment resulted from the in-vitro study; i.e., nicotinic acid (5mM, 10mM and 15mM), potassium silicate (8ml/L, 10ml/L and 12ml/L), T. harzianum (1x106 spores/ml), T. hamatum (1x106 spores/ml), B. subtilis (1x106 cfu/ml) in comparison with the fungicide Maxim® (143ml/L) (for 8-12 hr for all treatments and 1 time for Maxim®) before sowing. Maxim® was the most effective treatment in reducing the disease. It was followed by nicotinic acid (5mM) and T. harzianum. 3.2. In the fields : Sugar beet seeds were soaked in the most effective concentrations/treatment resulted from the greenhouse study; i.e.,, nicotinic acid (5mM), potassium silicate (12ml/L), T. harzianum (1x106 spores/ml), T. hamatum (1x106 spores/ml), B. subtilis (1x106 cfu/ml) in comparison with the fungicide Maxim® (143ml/L) (for 8-12 hr for all treatments and 1 time for Maxim®) before sowing. Maxim® and nicotinic acid (5mM) were the most effective treatment in reducing the percentage of damping-off disease, disease severity index (percentage) and disease incidence (percentage) of sugar beet. On the other hand, they enhanced the content of the photosynthetic pigments, total phenols, total soluble solids (TSS) and the growth parameters including root weight, root length, root diameter, foliage weight and foliage length of sugar beet plants. Therefore, this study recommends the use of nicotinic acid at a concentration of 5 mmol (soaking seeds) in fighting the diseases of sugar beet roots caused by the fungus F. moniliforme. It is also recommended to continue searching for safe alternatives to control plant diseases that affect vegetables, fruits and field crops as part of the environment and human protection system from chemical pesticides harmful effects after this study demonstrated the effectiveness of a large number of them in fulfilling this role.