تاثير متيل جازمونات و ساليسيليك اسيد در افزايش تحمل به سرماي گياه فلفل دلمه اي

چكيده انگليسي :

Effects of Methyl Jasmonate and Salicylic Acid on Cold Tolerance of Bell Pepper Seedlings Yosra Moradmand Yosra Moradmand@Yahoo com 6 April 2011 Department of Horticultural Sciences Isfahan University of Technology Isfahan 8415683111 IranDegree M Sc Language FarsiSupervisor Prof M Mobli Mobli @cc iut ac irAbstractBell pepper is one of the most important vegetables in the world regarding its nutritional andeconomical values for human being It is a warm season crop which is sensitive to low temperaturesand when its seedlings exposed to low non freezing temperatures showes chilling injury Lowtemperature is one of the important enviromental factors in agriculture that limits the survival productivity and geographical distribution of plants in large areas of the world Agricultural comoditiesspecially horticultural crops suffer from different enviromental stresses such as cold temperatureswhich estimated annually to be milliards of dollars Therefore using different methods in order tomake crops more tolerant to stresses is necessary Among the Chemicals that their effects on reducingchilling injury has recently been studied are salicylates and jasmonates Salicylic acid SA jasmonicacid JA and their methyl esters MeSA MeJA are endogenous signal molecules that play essentialroles in regulating stress responses and plant development Since bell pepper is sensitive to lowtemperatures a study in two separate experiments was carried out on two different cultivars of Emily a greenhouse cv and PS301 a field cv to find out the effects of salicylic acid and methyljasmonate on increasing the tolerance of bell pepper to chilling temperatures Both trials were done as7 2 factorial experiments in the completely randomized design CRD with four replications The firstfactor contains salicylic acid in three concentrations of 0 1 0 5 and 1mM and methyl jasmonate in theconcentrations of 0 001 0 01 and 0 1mM pluse control distilled water and the second factor was themethod of application of hormone that involved spraying plants and soil drenching Three days afterapplication of hormones plants moved to incubator in 0 centigrade under the photoperiods of 8 hoursof light and 16 hours darkness After 3 days the seedlings were returned to greenhouse temperature inorder to show visible symptoms of chilling injury Three days later visible chilling injury symptoms necrotic lesions chlorophyll fluorescence Fv Fm chlorophyll content relative water content RWC and electrolyte leakage were measured To measure factors such as chlorophyll a and b solublesuger proline and starch later 0 1 gram of leaf samples were kept in a freezer of 70 C followingsoaking in liquid nitrogen The results of both experiments showed that salicylic acid and methyljasmonate treatment increased bell pepper plant tolerance to chilling stress compared to untreatedplants Salicylic acid was more effective than methyl jasmonate Salicylic acid in the rate of 0 1mM inboth cultivars for all measured parameters improved situation following chilling compared to untreatedplants Methyl jasmonate in concentrations of 0 01 mM in Emily and 0 001 mM in PS301 were moreeffective than 0 1 mM in reducing chilling stress Thus it seems lower concentrations of salicylic acidand methyl jasmonate were more effective Also in most cases results showed that there was nosignificant differences between two methods of applications of hormone In the present study factorsof chilling injury necrotic lesions chlorophyll fluorescence Fv Fm chlorophyll content chlorophylla and b soluble sugers and proline were reliable measures compared to relative water content RWC electrolyte leakage and starch content in the study of chilling tolerance in bell pepper plants Key Words Bell pepper Chilling injury Methyl Jasmonate Salicylic Acid

مرادمند، يسري

تاثير متيل جازمونات و ساليسيليك اسيد در افزايش تحمل به سرماي گياه فلفل دلمه اي

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