SALICYLIC ACID MEDIATED PHYSIOLOGICAL AND BIOCHEMICAL ALTERATIONS TO CONFER DROUGHT STRESS TOLERANCE IN ZINNIA (Z. ELEGANS)

Background: Protective role of salicylic acid against drought has been widely reported, but its effects on Zinnia elegans remain unknown. Hypotheses: Foliar salicylic acid (SA) improves water status, pigments, and antioxidant systems of Zinnia plants under drought stress. Studied species: Z. elegans (cv. Dreamland) were purchased from Chanan Seeds Store Lahore, Pakistan. Study site and dates: MNS University of Agriculture, Multan, Punjab, Pakistan; March-May, 2018. Methods: After two weeks of transplanting, one set of seedlings was exposed to drought stress (60 % field capacity, FC) while other control set was maintained at 100 % FC. Foliar SA (100 mg L-1) was applied to plants at drought initiation. Results: Foliar SA treatment to water stressed plants (60 % FC) increased the leaf area (46.89 cm(2)), shoot and root lengths (25 cm and 26.67 cm, respectively), leaf relative water content (75.98 %); chlorophyll a (0.68 mg g(-1)), chlorophyll b (0.38 mg g(-1)) and carotenoid concentrations (1.10 mg g(-1)); and catalase (116.67 U min(-1) mg(-1) protein), guaiacol peroxide (72 U min(-1) mg(-1) protein) and superoxide dismutase (93 U min(-1) mg(-1) protein) activities. Conclusions: Foliar SA could be used to minimize impacts of water stress in Zinnia plants.