بررسي ارتباط خصوصيات سيستم ريشه اي و فيزييولوژيك با تحمل به تنش خشكي در ژنوتيپ هاي فسكيوي بلند

چكيده انگليسي :

116 Study of Root and Physiological Traits Associated with Drought Tolerance in Tall Fescue Genotypes Fatemeh Pirnajmedin f pirnajmedin@yahoo com Data of Submission on 1 June 2014 Department of Agronomy and Plant Breeding Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Mohamad Mahdi Majidi majidi@cc iut ac irAbstractDrought stress represents the most limiting factors for agricultural productivity in arid and semiarid region ofthe world Research on crop response to deficit irrigation is important to reduce agricultural water use inareas where water is a limited resource The objectives of this study were to evaluate the response ofmorphological and biochemical traits under mild and intense drought stress and its association with fielddrought tolerance in tall fescue Twenty four genotypes of tall fescue were selected from a wide polycrosspopulation that evaluated for drought tolerance during 2009 2012 in field Genotypes were classified totolerant moderately tolerant and susceptible based on drought stress tolerance index STI tolerance index TOL In 2013 twenty four genotypes were clonally propagated and planted in PVC tubes 60 16 cm formeasure morphological and biochemical traits Genotypes were assessed under three levels of moistureregime control mild and intense drought stress according to a factorial experiment based on a completelyrandomized design with 3 replications Root characters were measured at 0 30 and 30 60 cm depths of root The results showed that drought stress significantly affected all of the measured traits There weresignificant difference between genotypes for all of the measured traits indicating the broad genetic diversityin this germplasmand successful selection in this germplasm The interaction of moisture environment andgenotype was also significant for measured traits Effects of drought stress on dry forage weight weresignificant Weight reduction from control to mild and intense drought stresses as 14 13 and 50 21 respectively With augmentation of the drought stress the root shootratio increased compared with control7 69 and 54 16 in 0 30 cm and 30 60 cm depth of root respectively Under mild and intense drought stress the root length increased 5 95 and 7 30 in 30 60 cm depth of root respectively Drought stress led tosignificant increase in amount of the cartenoeid chlorophyll a chlorophyll a b proline water solublecarbohydrates and activity of peroxidase compared with control In mild drought stress dry forage weight hadpositive correlation with root length root volume root area root wet weight and root dry weight This mayindicate that indirect selection can lead to genotypes with high yield Relative water content had positivecorrelation with catalase and ascorbate peroxidase under intense drought stress On the basis of stepwiseregration analysis crown diameter under control root wet weight under mild stress and root to shoot ratiounder intense drought stress justified the majority of dry forage weight variation Factor analysis for all ofthe traits revealed seven factor under control and six factor under mild and intense drought stresses whichjustified more than 75 percent of the total variation The results of cluster analysis under three moistureregimes and application of principle component analysis under mild and intense drought stress showed that some tall fescue genotypes don t have extensive root system and suitable physiological traits related todrought tolerance also had low STI and high TOL indices in field condition From this genotypes can refer to2 early and 3 late that susceptible to drought stress Some other tall fescue genotypes had high extensive rootsystem photosynthetic capacity and yield productivity also had low TOL and high STI indices in fieldcondition These genotypes cosist of 14 early 2 late 11 17 and 23 medium These adapt and tolerant todrought through drought avoidance and drought tolerance mechanisms that can be used for future breeding

پير نجم الدين، فاطمه

بررسي ارتباط خصوصيات سيستم ريشه اي و فيزييولوژيك با تحمل به تنش خشكي در ژنوتيپ هاي فسكيوي بلند

طول ريشه , آنزيم پراكسيداز