Document Type : Original Article
The effects of exogenous abscisic acid (ABA) and its two agonists, Sulfacetamide (Sa) and Sulfasalazine (SS) on tolerance of tomato (Lycopersicon esculentum Mill. Cv. Super chief) under drought stress were studied. Eight-week plants were treated with ABA (25 and 50 mg/L), Sulfacetamide (Sa) (25, 50 and 100 mg/L) and Sulfasalazine (SS) (25, 50 and 100 mg/L). Solutions were sprayed daily and sampling was done at 48 h, 96 h, 144 h and 48 h after re-watering (recovery phase). Treated plants showed relatively greater drought tolerance. This indicates that, Sulfacetamide and Sulfasalazine improved resistance in tomato, like ABA, increasing activity of antioxidant enzymes, i.e., catalasthise (CAT), ascorbate peroxidase (APX)and guaiacol peroxidase (GPX). On the other hand, abscisic acid, Sulfacetamide and Sulfasalazine reduced H2O2 and MDA contents in the plants under study. Daily application of these agonists during moisture stress period was effective in increasing tomato plants tolerance to drought as was ABA.