Effect of Drought on Different Physiological Characters and Yield Component in Different Varieties of Syrian Durum Wheat

Tolerant and susceptible durum wheat varieties were grown in the 1 and 2 settlement zone under rainfed conditions inDaraa province-Syria, In order to expose plants to different level of water regime, since the two zones differ in total amount of rainfall during the growing season. Plants were suffered from terminal drought stress in both zones, however, the drought was more sever in the 2 settlement zone. All measured parameters: chlorophyll content, MSI, RWC, Fv/Fm decreased significantly in the 2 compared to the 1 zone at all growth stages, however more reduction was recorded in drought susceptible varieties. Yield all yield components also affected negatively and drought tolerant varieties have maintained good performance in the 2 zone. Our results proved that Chlorophyll content, MSI, RWC and Fv/Fm are good physiological indices of drought tolerance and can be used for improvement drought tolerance in wheat.