الفهرس 
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Abstract
SUMMARY
The present investigation was planned to study isolation of causal organisms bacterial soft rot disease of leafy vegetable crops which collected from different locations and their identification using traditional and modern methods. Also, to study the diversity between different isolates of the pathogen and controlling the disease using biotic and abiotic agents individual and/or combination under experimental greenhouse and field condition.
The results obtained can be summarized as follows:
1. Approximately 66 samples of infected leafy vegetable crops (lettuce, parsley, cabbage, and watercress) leaves with bacterial soft rot disease were collected from different regions of Qalyubia and Sharkia governorate, during growing seasons 2015 and 2016. Where, 91 bacterial isolates were obtained from diseased leaves of vegetable crops which collected from Qalyubia (47 isolates) and Sharkia (44 isolate).
2. According to a hypersensitive test on the tobacco plant, 34 bacterial isolates showed a positive result in inoculated tobacco leaves as water-soaked, yellowing and brown died areas.
3. Lettuce plants were inoculated by 34 bacterial isolates previous to study pathogenicity test, under greenhouse conditions. Tested isolates gave positive results, where, 11 bacterial isolates were high severity, 9 bacterial isolates were severed disease, 12 bacterial isolates were moderately severity and 3 bacterial isolates were less severity.
4. All obtained isolates were short-rod, negative staining, non-sporulation and positive with KOH 3% as morphological characters. According to cultural characters on nutrient glucose agar (NGA) and yeast extract calcium carbonate (YDC) media and production of pigment florescent on King’s B (KB), three groups of bacteria were determined as the following, the first group was were irregular - round , convex , smooth surface , entire margin and yellow color and non-pigment florescent on King’s B (KB), the second group was irregular - round , flat , smooth surface , entire margin and translucent color and pigment florescent on King’s B (KB) and the third groups were irregular - round , convex , smooth surface , entire margin and white color and non-pigment florescent on King’s B (KB).
5. The first group was positive results with starch hydrolysis, gelatin liquefaction, Levan production, Catalase, arginine production, pectin hydrolysis and utilization of sucrose, fructose, glucose, mannose and sorbitol, and were negative results with oxidase, growth at 37°c and utilization of lactose and mannitol.
6. The second group gave positive results with growth at 37°c, Catalase, gelatin liquefaction, pectin hydrolysis and utilization of sucrose, fructose, glucose, mannitol and mannose and negative results with starch hydrolysis, Levan production, oxidase, arginine production and utilization of lactose and sorbitol.
7. The third group showed positive results with growth at 37°c, Levan production, Catalase, gelatin liquefaction, pectin hydrolysis and utilization sucrose, fructose, glucose, mannitol and mannose and negative results with starch hydrolysis, oxidase, arginine production and utilization of lactose and sorbitol.
8. According to Bergeyʾs Manual of determination Bacteriology using morphological, cultural, physiological and biochemical characters, the first group bacterium was identified as Xanthomonas sp., the second group bacterium was identified as Pseudomonas sp. and the third group bacterium was identified as Pectobacterium sp.
9. Nine bacterial isolates (three isolates of each genus Xanthomonas sp., Pseudomonas sp., Pectobacterium sp.) were selected to study molecular diversity using RAPD-PCR with different primers to confirm the identification. While, tested isolates are different in their genome with the used primer, where Xanthomonas sp. isolates were noticed at molecular weight of 700bp, isolates of Pseudomonas sp. were noticed at a molecular weight of 200bp and Pectobacterium sp. isolates were noticed at a molecular weight of 300bp .
10. Also, to confirm the identification was used BIOLOG test, the first group belong to Xanthomonas campestris, the second group belong to Pseudomonas marginalis the third group belongs to Pectobacterium carotovorum .
11. Four bactericides i.e. norfloxacin, gentamycin, streptomycin and tetracycline were examined on the growth of bacterial soft rot pathogens (P. carotovorum, Ps. marginalis and X. campestris), In vitro.
12. The growth of bacterial soft rot pathogens was reduced with the application of all bactericides compared with the control treatment. Efficacies of tested bactericides were increased with increasing their concentrations. While, norfloxacin and tetracycline were the most efficacy, but gentamycin and streptomycin were moderately efficacies against the growth of tested bacterial soft rot pathogens. Also, tested bactericides, more effective on the growth of X. campestris bacterium than P. carotovorum, and Ps. marginalis bacteria.
13. Isolates of B. megaterium, B. subtilis, Ps. fluorescens and S. marcescens as antagonistic bacteria were tested against the growth of pathogenic bacteria soft rot i.e. P. carotovorum, Ps. marginalis and X. campestris In vitro.
14. Tested antagonistic bacteria were reduced the growth of P. carotovorum, Ps. marginalis and X. campestris bacteria as soft rot pathogens compared with the control. Isolate of Ps. fluorescens was the most efficacy but isolates of B. megaterium and B. subtilis were moderately efficacy and S. marcescens isolate was less effective against the growth of bacterial soft rot pathogens. Also, tested bio-agents were more effective against the growth Ps. marginalis bacterium than P. carotovorum and X. campestris bacteria.
15. Application of resistance inducers ( jasmonic acid and salicylic acid ) as foliar and seedling treatments, bactericides (norfloxacin and tetracycline ) as foliar treatment and bio-agents (B. subtilis and Ps. fluorescens isolates) as foliar and soil treatment were examined individual and/or combination to control bacterial soft rot disease of lettuce (inoculated plants with P. carotovorum, Ps. marginalis and X. campestris ), under greenhouse conditions experiments.
16. Tested resistance inducers, bactericides and bio agents were decreased from severity of lettuce bacterial soft rot disease compared with the control treatment. While, combination treatments were more efficacy than individual treatments against the disease. Resistance inducers and antibiotics were the most effective to control the disease compared with bio agents. Application of resistance inducers, bactericides, isolates of B. subtilis (bio agent) as foliar treatment and Ps. fluorescens isolate (bioagent) as soil treatment appeared most effective against disease of the lettuce bacterial soft rot compared with other treatment.
17. Salicylic acid as resistance inducers, tetracycline as bactericide and Ps. fluorescens isolate as bio-agent showed most efficacy to control the disease compared with other treatments. All tested factors were the most effective to control soft rot disease caused by P. carotovorum bacterium compared with other diseases caused by Ps. marginalis and X. campestris bacteria.
18. Interaction between bio-agent (Ps. fluorescens) as soil drench treatment and bactericides and/or resistance inducers as foliar treatment and interaction between bactericide (norfloxacin) as foliar treatment and resistance inducers as foliar treatment gave most effective against the disease of bacterial soft rot compared with other treatments. Interaction between norfloxacin, as a bactericide and salicylic as resistance inducers was the most efficacy against the disease, but interaction between B. subtilis isolate as bio agent and jasmonic acid as resistance inducers was less efficacy and other interaction were moderately efficacy to control the disease.
19. Field experiments carried out under natural infection conditions at Qaha region, Qalyubia governorate. Bio-agents (isolates Ps. fluorescens and B. subtilis) as soil drench treatment, bactericides (norfloxacin and tetracycline) as foliar treatment and resistance inducers (jasmonic acid and salicylic acid) as foliar treatment were applied individual and/or combination to control lettuce bacterial soft rot disease.
20. All mentioned factors previously were decreased from the severity of lettuce bacterial soft rot disease compared with the control treatment, disease severity was more reduction with interaction treatments than individual treatments. Resistance inducers appeared most efficacy to control the disease, but bio-agents were moderately effective and bactericides were less effective against the disease, salicylic acid showed most effective and tetracycline was less effective against the disease of lettuce bacterial soft rot disease.
21. The combination between resistance inducers and bactericides or bio-agents was most efficacies to control bacterial soft rot disease of lettuce and combination between bio-agents and bactericides were moderately efficacy to control the disease. The combination between salicylic acid as resistance inducers and norfloxacin as bactericide or Ps. fluorescens isolate as bio-agent gave the best treatment to control lettuce bacterial soft rot disease compared with other treatments, but the interaction between tetracycline as bactericide and bio-agents appeared less efficacy and other treatments were moderately effective against the disease.