5560
Tarek Gomaa Abdel- Gaied Abdou
Strains Of Erwinia Carotovora The Causal Agent Of Soft Rot Of Some Vegetables And Its
Control In Egypt
Erwinia carotovora strains, Control, Field application, Host range, Potato tubers quality, Protein fingerprints, Storage.
The aim of this study is to isolation and identification Erwinia carotovora bacteria as causal agent of soft rot disease in some vegetables. Samples were collected from the storage and marketing places in Giza and Beni Suef governorates. Four isolates (potato tubers); one isolate (sweet potato); three isolates (cucumber); three isolates (carrot); two isolates (eggplant); one isolate (red sweet pepper); two isolates (chili) and one isolate (tomato) were isolated, from naturally infected plant samples according to standard bacteriological methods, on nutrient glucose (2%) agar medium. These bacterial isolates were showed a variation in their pathogenicty on host range or their ability for fermentation of tested sugars. According to cultural, physiological and biochemical characters 15 bacterial isolates were defined as E. carotovora subsp. carotovora, while two isolates as Erwinia. chrysanthemi. The protein fingerprint of isolates differed in their number of discrete protein bands, their molecular weight and the similarity between them. The tree dendrogram showed that bacterial isolates can be divided into two main groups. In vitro tests, bio-agents, aqueous plant extracts and chemicals, using filter paper disc plate method in Petri dish, had different antagonistic effects against bacterial soft rot isolates. In vivo tests, the above materials by using artificially inoculation on potato slices, the crude cultural filtrates of bacterial bio-agents were highly efficacy in reducing the symptoms of soft rot on potato slices, when applied 2h.before or at the same time of inoculation, while treatment potato slices with Trichoderma spp. were highly effective when applied 2h.after or at the same time of inoculation. Aqueous plant extracts also showed high efficacy in inhibiting the soft rot incidence on potato slices, when applied 2h.before or 2h.after of inoculation. The tested chemicals were limited in their effectiveness aganist soft rot incidence at the inoculation times. In vivo tests by using whole potato tubers, the treatments were able to protect the stored potato tubers for different times. Field experiment treatments protected the daughter potato tubers against soft rot infection, enhanced the plant growth and yield parameters of potato plants as well as activation of some defense related enzymes (i.e. peroxidase, polyphenole oxidase & chitinas). Storage results showed that the treatments, as soil or foliar spray, enhanced the quality parameters of stored potato tubers viz. dry matter, reducing sugars, carbohydrates, specific gravity and starch content. The foliar spray was the better than soil treatment for protection of stored potato tubers
2019
M.Sc
Cairo
Agriculture