Amin Abbasi

In this study wheat plants were treated with paclobutrazol (PBZ) and salicylic acid (SA) to analyze the enzyme activity and chlorophyll content under two drought stresses (-6 and -12 bar). The Bahar cultivar was grown in a hydroponic system and drought stress was applied using PEG-6000 (-6 and -12 bar potential). Plants were kept under stress conditions for 10 days. Treatments with 5 mg L -1 paclobutrazol and 0.1 mm salicylic acid were carried out simultaneously with drought stress. The effects of PBZ and SA treatments on wheat were monitored by measuring the changes in CAT, APX, SOD, GPX, MDA, H and chlorophyll under drought stress. Both PBZ and SA increased antioxidant enzyme activity and showed significant differences (p< 0.001 and 0.05). APX, SOD and CAT activity decreased under the drought condition but PBZ treatment resulted in increased APX activity in the drought stress treatment. However, seedlings supplemented under drought stress showed a profound increase in GPX activity (100% and 53% higher at -6 and -12 bar PEG on 3D) compared to stressed seedlings without SA spray. The results showed that paclobutrazol minimizes the negative effects of drought stress with evidence of enhancing chlorophyll content and antioxidant enzymes such as APX, CAT and GPX that reduces H2O and lipid peroxidation (MDA) content.