الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Soybean root-rot disease is very important where it causes seedling damping- off and great loss of yield production. The present investigation aimed to friend ou some environmental friend method to conrol this disease. The obtained results could be summarized as following: 1- Fusarium solani, Rhizoctonia solani and Macrophomina phaseolina were the dominant associated fungi with root-rotted soybean plans collected from Giza, Minia, Minoufiya and Sharkia Governoraes. 2- The three mentioned fungi were pathogenic o Giza 21 soybean cultivar and F. solani isolae of Minia governorate was more aggressive than the others. Also, R. solani (Minia isolates. Macrophomina phaseolina isolates were slightly pathogenic to Giza 21 soybean cultivar. 3- In vitro studies proved that Trichoderma spp. Overgrow on the pathogen mycelia and cause lyses of them except that of M. phaseoline. While Bacillus spp. Cause inhibition zones between them and the pathogen (s). 4- All tested biocontrol agents reduced the growth of the ested pathogenic fungi. Bacillus megaterium was the best where it reduced the growth of F. solani and M. phaseoline by 61.1, 50.0 and 40.5% respectively . 5- Under greenhouse and artificial soil infestation observed that soybean cultivars Giza 3, Giza 35 and Crawford were highly susceptible to either F. solani or R. solani. While Giza 21, Giza 22 , Giza 82 and Clark cultivars were less susceptible to the tested pathogens. 6- All tested biocontrol agents reduced root-rot disease incidence significantly. Trichoderma harzianum was the best in reducing pre-emergence damping – off due to F. solani. While B. megaterium was more effective against R. solani. In the meantime, T. koningii showed much better effect against M. phaseolina. 7- Application of chemical inducers to soybean seeds just before planting decreased root-rot disease incidence and increased the survival plants. Oxalic acid at the rate of 200 ppm showed the best results where it resulted 99.7 and 98.0% survival plants of Giza 21 and Giza 35, respectively. 8- Thyme, camphor and cumin oils significantly reduced root-rot disease incidence when applied to soybean seeds just before planting at the rate of 5 and 10 ppm. 9- Under field and natural soil infestation condition; the tested control methods in greenhouse were tried. Individual seed treatments with Salicylic acid, Oxalic acid, potassium phosphate and Ethephone, reduced the disease incidence than control significantly. Oxalic acid, Salicylic acid and Potassium phosphate were better than Rizolex-T in reducing root-rot disease. 10- All tested inducers increased plant height of Giza 35 soybean cultivar than control significantly. They also increased plant height of Giza 21 cultivar significantly except Ethephone and Neem oil which insignificantly increased plant height. Average number of branches was insignificantly increased in response to inducers application. 11-High significant increase of yield production was obtained in response to the inducer applications. Oxalic acid and Salicylic acid were the best for increasing yield production and the average of hundred seeds weight. 12- Treating soybean seeds with different plant oils reduced root-rot disease incidence of both Giza 21 and Giza 35 soybean cultivars. Thyme and / or cumin oils showed the best results. Plant height and the average number of branches / plant were improved for such applications. 13- Yield of both tested cultivars was also increased in response to oil treatments at 2010 and 2011 growing seasons. 14- The activity of some enzymes were determined in 30 days old soybean plants (Giza 21 cultivar) growing from seeds treated with Salicylic acid, Oxalic acid, Potassium phosphate, Ethephone, Neem oil and Rizolex-T, individually. Peroxidase activity was highly increased in response to the application of Rizolex-T, Salicylic acid and Oxalic acid(188,183 and 174% of control, respectively). In the same respect, polyphenol oxidase activity was 131, 126 and 117% compared to the untreated control. However, chitinase activity reached 267, 245 and 240 % of control, respectively with Rizolex –T, Salicylic acid and Oxalic acid. 15- The activity of peroxidase, polyphenol oxidase and chitinase were increased than control in response to seed treatments with either cumin, eucalyptus, thyme, mint and jasmonium oils (10%). The best increment of enzyme activities were recorded when thyme and cumin were used (polyphenol oxidase and chitinase).In general, Rizolex-T was more effective in all tested enzymes activity.