وراثت پذيري فعاليت آنزيم هاي آنتي اكسيدان و پايداري غشاي سيتوپلاسمي در گندم نان و نقش آنها در تحمل تنش خشكي انتهايي

Inheritance of Antioxidant Enzymes Activity and Cell Membrane Stability in Bread Wheat and Their Role in Terminal Drought Tolerance

To evaluate the inheritance of antioxidant activity and cell membrane stability in bread wheat, the F1 seeds of a 7><7 half diallel along with their parents were grown in greenhouse of Ardebil Islamic Azad University in both a well watered and terminal drought conditions in 2008. After exposure of plants to drought, flag leaves were collected for enzyme activity and cell membrane for stability measurement. For evaluating the relationship between enzyme activity and cell membrane permeability with drought tolerance, 18 wheat varieties were grown in RCB with 3 replications under normal and terminal drought conditions in the field. Results showed that index of injury (Id), ascorbate peroxidase (APX) and catalase (CAT) activity are under control of both additive and dominant effects. However in superoxide dismutase (SOD) activity, additive effects were not significant. Among the traits APX had the highest narrow sense heritability, followed by moderate heritability for CAT, and low heritability for SOD an Id. In general all of traits had high broad sense heritabilities. Strong and positive correlations among activity of antioxidant enzymes and drought tolerance were observed. Higher SOD and APX activity have been correlated with relatively lower injury index; however, injury index did not affected by CAT activity. The osmotic membrane permeability of leaf segments under PEG induced stress showed high broad sense heritability. Id did not show any significant correlations with drought tolerance. It concluded that membrane injury caused by PEG induced osmotic stress is not a representative simulation of drought stress.