بررسي مقاومت به سرما در گونه هاي اكاليپتوس

چكيده انگليسي :

۵۶ Evaluation of Cold Stress Tolerance in Some Eucalyptus Genotypes Soheila Lahijanian s lahijanian@gmail com 13 March 2012 Department of Horticultural Science Isfahan University of Technology Isfahan 8415683111 IranDegree M Sc Language FarsiSupervisor Prof M Mobli Mobli @cc iut ac irAbstractlow temperature extremes is among the major stresses that adversely affect plant growth and productivity Cold stress causes oxidative stress physiological morphological and biochemical changes in plant cells Generally low temperatures similar to salinity and drought exert their negative effects mainly by disruptingthe ionic and osmotic equilibrium of the cell Changes in climatic condition leading to more frequent extremeconditions will require adapted crop species on a larger scale in order to sustain agricultural production Eucalyptus is a diverse genus of flowering trees and a few shrubs in the myrtle family Myrtaceae Members of this genus dominate the tree flora of Australia The Eucalyptus genus contains more than 580species and also large number of cultivars which are native to Australia Large distribution and diversity ofcompatible Eucalyptus cultivars reflect the fact of ecological felexibility of Eucalyptus Some eucalyptuscultivars can sustain hard environmental condition like high and low temperature salinity high level of PHand drought Chilling and freezing are intensively effective on crops with tropical and subtropical origin suchas Eucalyptus and most of the time it can be lethal for them In this study we tried to evaluate cold toleranceof 12 Eucalyptus genotypes by means of four different methods Chlorophyll Fluorescence Electrolyteleakage Proline and Stomatal density These cultivars include six cultivars which are planted in Iran and siximported native cultivars from Australia Except for stomatal density recording in other methods plants areexposed to five gradual temperature drop 0 5 10 15 and 20 degree of centigrade and they remained inthese temperatures for at least one hour Experiment for measuring chlorophyll fluorescence was done as5 12 factorial in compeletely randomized design with three replicates This experiment showed thatgenotypes no 18 Eucalyptus erythrocorys and 13 were the most resistant genotypes and 2 E gunnii and11 E coccifera were more sensitive than others Electrolyte leakage experiment also was done as a 5 12factorial experiment through complete randomized design CRD with three replications With regards tosignificant interaction between cultivar and temperature and low increase in electrolyte leakage from 5 to 10 genotypes 18 E erythrocorys and 17 E macrocorpa are shown to be most tolerant genotypes and 2 E gunnii 3 E urnigera 14 15 and 16 with the more ionic leakage percentage showed to be moresensitive to low temperatures Proline experiment was done in the form of 5 5 factorial through completerandomized design CRD with three replications Results of this experiment approved that the more resistantgenotype in relation to cold stress is 18 e Erythrocorys In the stomatal density experiment the number ofstomata under microscopic field were counted and the results showed that the 18 E Erythrocorys and 17 E macrocorpa genotypes had the maximum and 11 E coccifera and 12 E dalrympleana genotypes hadminimum number of stomata under microscopic field 0 0605 mm2 As a conclusion a remarkablecorrelation was not obtained between the stomatal density and other cold stress measures key word Cholorophyll Fluorescence Cold Stress Ionic leakage Proline Stomataldensity

لاهيجانيان، سهيلا

بررسي مقاومت به سرما در گونه هاي اكاليپتوس

پرولين , تراكم روزنه , سرمازدگي , فلورسانس كلروفيل , نشت يوني