الفهرس 
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Abstract
This study was concerned with the effect of different antioxidents on controlling Ralstonia solanacerum the causal agent of potato bacterial wilt disease. thirteen antioxidants divided in to 5 groups organic acids groups (salicylic acid, ascorbic acid and humic acid), extracts (sea weed extract and yeast extract),organic compounds (glutathione and chitosan), volatile oils (thyme, caraway, camphor and lemon) and minerals( CaNO3 and ZnSO4 ) were studied in vitro and in vivo . Pathology, physiological and enzyme activity were estimated, also studying the effect of P fluorescent in combination with SA on suppressive of bacterial wilt disease.
In vitro the most effective treatment was thyme oil followed by chitosan and the least effective was camphor and lemon oils.
Under green house condition The most effective groups was extracted followed by organic compounds. The most effective antioxidants were ascorbic acids ,sea weed extract, yeast extract, chitosan ,GSH and thyme oil. Most of applied antioxidants increase vegetative growth compared to positive control but this increase still less than negative control.
Ascorbic acid is the most effective in reducing 70% in wilt severity and 50% in latent infection as expressed by the count of the pathogen in crown area. Sea weed extract was more effective than yeast extract. Sea weed reduced the count of the pathogen in soil into half and also the count of the pathogen in crown area with complete absence of wilt severity and AUDPC
Glutathione (GSH) and chitosan. Both were effective in disease suppression but chitosan was more effective. Only thyme oil gave promising disease suppression while lemon oil gave the poorest results in this regard.
All tested antioxidants gave significant increase in all parameters of vegetative growth. Chlorophylls increased while phenols decreased in general. Endogenous ascorbic acids increased. Increased in POX ,SOD as well as CAT activity.
The most effective treatment was SA+ P.f (decrease the count in soil, the pathogen disappear from plant rhizospher, crown area and AUDPC) followed by SA only which eliminate the pathogen from soil and rhizospher and decrease the count in crown area.Pf was the most effective in improving growth parameters followed by Pf + SA then SA alone
In chemical constituents and enzyme activity Pf + SA was the most effective increasing all parameters except catalase followed by SA increasing (phenol ,Chl ,carotenoids, SOD and POX)then Pf only increased (Chl , carotenoids and SOD).