4988

4692

كارشناسي ارشد

خاكشناسي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده كشاورزي

1388

سيزده،88ص:مصور، جدول، نمودار

ص.ع. به: فارسي و انگليسي

امير حسين خوشگفتارمنش، مهران شيرواني

بهرام شريف نبي، نفيسه نيلي

6/11/88

حسين شريعتمداري،امير مساح

مهندسي كشاورزي

ID4692

به فارسي و انگليسي: قابل رويت درنسخه ديجيتال

Silicon Application Effect on Tolerance of Two Cucumber Genotypes to Phytophthora melonis Root and Crown Rot Parvane mohaghegh Mohaghegh2002@gmail com 18 October 2009 Department of Soil Science Collage of Agriculture Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiDr A H Khoshgoftarmanesh amirhkhosh@cc iut ac irAbstractAlthough silicon Si is not known as an essential plant nutrient but has severalbeneficial effects in plant Soluble Si may activate defense mechanisms in cropsagainst biotic stresses including root rot diseases The Phytophthora melonis is one ofthe most important root rot diseases and the main agent responsible of green death incucumber We hypothesized that Si affects physiological and biological mechanismsin cucumber plants to improve the crop tolerance to disease stress Thus the aim ofthis study was to investigate the influence of Si on the tolerance of two cucumbergenotypes Cucumis sativus L cvs Dominus GRC and Super Dominus toPhtophthora melonis infection In a hydroponics experiment two cucumber cultivarswere exposed to three Si levels 0 100 and 200 mg L 1 Si and two Phytophthoramelonis inoculums levels with and without inoculation of P melonis Shoot and rootdry matter yield root membrane permeability reactive sulfhydryl groupconcentration activity of catalase CAT and ascorbate peroxidase APX in theroots and concentration of zinc Zn iron Fe manganese Mn and silicon Si inthe roots and shoots were determined After plant harvesting the severity of P melonis infection was assessed in terms of the number of roots with at least onepathogen lesion Supplement of Si in the nutrient solution increased the Siconcentration in the cucumber tissues The root length and root and shoot dry weightof cucumber plants was significantly P 0 05 greater in the presence of Si to thecompared with Si free treatments In both cucumber cultivars in the presence of P melonis infection Si nutrition significantly P 0 05 decreased the root membranepermeability and increased the activities of CAT and APX in the root There was nosignificant difference in the reactive sulfhydryl group content between the infectedand non infected cucumber plants Silicon nutrition significantly P 0 05 decreasedthe disease induced injurious effects on the cucumber roots Zinc and Mnconcentration in the roots decreased but the roots and shoots concentration of Feincreased as a result of Si nutrition Application of Si had a positive effect on thetolerance of cucumber to P melonis root rot disease The results showed that Siaddition to the nutrient solution of cucumber may reduce the membrane oxidativedamage induced by fungal infection and thus improve crop tolerance to disease Key words Silicon Phytophthora melonis infection Cucumber Plant tolerance

امير حسين خوشگفتارمنش، مهران شيرواني

بهرام شريف نبي، نفيسه نيلي

حسين شريعتمداري،امير مساح