الفهرس 
ACKNOWLEDGEMENT
Pathogenicity testsOnly 14 pages are availabe for public view
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Abstract
Results of the present work can be summarized as follows:
1. The fourteen isolates of Botrytis allii isolated from different localities of Upper Egypt were able to infect Giza 6 onion cultivar and produce typical symptoms of neck rot with different degrees of infection. Isolates No. 8, 9, 12, and 13 caused the highest percentage of infection followed by isolate10 then isolate 11 and isolate14. Isolate 7 exhibited the lowest percentage of infection. The other tested isolates were moderately virulent.
2. It is widely known that certain sources of carbon and nitrogen may have an influence on the biological control efficacy against some pathogens. Gliotoxin fermentation agar (GFA) medium and nutrient glucose agar (NGA) medium amended with different carbon and nitrogen sources were used to study their antagonistic efficiency on Trichoderma harzianum and Bacillus subtilis against Botrytis allii. Results indicated that T. harzianum gave the highest inhibition % in growth of B. allii when sucrose was used as a carbon source while the lowest values of inhibition % were appeared by the application of mannitol as a carbon source. T. harzianum gave the highest inhibition % in growth of B. allii when Potassium nitrate was used as a nitrogen source while the lowest values of inhibition % in growth of B. allii were obtained by application of beef extract as a nitrogen source. Results also showed that B. subtilis gave the highest inhibition% in growth of B. allii when mannitol was used as a carbon source while the lowest values of an inhibition % in growth of B. allii were appeared by application of sucrose as a carbon source. B. subtilis gave the highest inhibition % in growth of B. allii when use glutamic as a nitrogen source while the lowest values of an inhibition % in growth of B. allii were appeared by application of tryptophan as a nitrogen source. It was found that using sucrose and potassium nitrate enhanced efficacy of T. harzianum as a biological agent, also using mannitol and glutamic acid enhanced efficacy of B. subtilis as a biological agent.
3. The chemical resistance inducers chitosan, potassium silicate and calciven at (500, 1000, 1500 mg/L) had no effect on the mycelial growth of B. allii isolate No.9.
4. Under field conditions treating Giza 6 onion bulbs before planting by dusting onion bulbs in the tested concentration of Trichoderma harzianum formulation or Bacillus subtilis formulation (5, 10,15g/kg onion bulbs) or by dipping onion bulbs in the tested concentration of chitosan or potassium silicate or calciven (5, 10,15ml / kg onion bulbs) caused significant differences in infection percentage of onion plants grown for seed production, seed stalk height, seed germination percent and 1000 seeds weight. In general, lowest infection percentage incidence in different treatments was achieved by calciven treatment followed by potassium silicate. Chitosan and Trichoderma formulation was exhibited intermediate effects. The lowest effect in both tested seasons was observed with Bacillus formulation treatment.
5. Treating Giza 6 onion bulbs before planting by dusting onion bulbs in the tested concentration of Trichoderma harzianum formulation or Bacillus subtilis formulation (5, 10,15g/kg onion bulbs) or by dipping onion bulbs in the tested concentration of chitosan or potassium silicate or calciven (5, 10,15 ml / kg onion bulbs) caused significant differences in the stalk height. The tallest stalks were obtained by application of calciven and by potassium silicate. Bacillus formulation and Trichoderma formulation were exhibited intermediate effects on onion plant stalk height.
6. Treating Giza 6 onion bulbs before planting by dusting onion bulbs in the tested concentration of Trichoderma harzianum formulation or Bacillus subtilis formulation (5, 10,15g/kg onion bulbs) or by dipping onion bulbs in the tested concentration of chitosan or potassium silicate or calciven (5, 10,15ml /kg onion bulbs) caused significant differences in seed germination % compared with the control. The highest percentage of germination was appeared with calciven followed by potassium silicate. The lowest combination was obtained by using Bacillus formulation under concentration of 5 g/k bulbs.
7. Treating Giza 6 onion bulbs before planting by dusting onion bulbs in the tested concentration of Trichoderma harzianum formulation or Bacillus subtilis formulation(5, 10,15g/kg onion bulbs) or by dipping onion bulbs in the tested concentration of chitosan or potassium silicate or calciven (5, 10,15ml / kg onion bulbs) caused significant differences in1000 seeds weight compared with the control. The highest value of 1000 seeds weight was appeared by application of potassium silicate followed by calciven. The lowest interaction was attained by using Bacillus formulation under concentration of 5 g/kg bulbs.
8. Under storage conditions dusting onion bulbs of Trichoderma harzianum or Bacillus subtilis formulations or spraying the tested inducers (chitosan, potassium silicate and calciven), the onion bulb infection% was significantly affected by the used substances in both seasons. The lowest percentage of onion bulb infection% was appeared by application of potassium silicate followed by calciven comparing with control treatment.
9. Results revealed also that the highest value of salicylic acid accumulation was obtained by application of calciven, while the lowest values were obtained by application of chitosan. Also the highest value of total accumulated phenols was appeared in treatment with chitosan followed by Bacillus formulation while the least value was appeared in calciven treatment.