Abstract

Salicylic acid (SA) is used in agricultural practices because it induces stress tolerance. The goal of this study was to determine the SA concentration in leaves, the change in catalase (CAT) activity and the change in total antioxidant capacity (TAC) that result from the exogenous application of SA (10^-4 M) to tomato leaves every 15 days in a greenhouse with and without NaCl application. Fruit yield was also verified. Treatments included SA + 100 mM NaCl, SA + 0 mM NaCl, water + 100 mM NaCl, and water + 0 mM NaCl. As a response to the foliar application of SA, the concentration of SA in leaf tissue exhibited a dynamic behavior that was similar to that reported when SA was induced by environmental stress. A similar phenomenon was observed for CAT and TAC activity after application of SA to leaves: CAT and TAC values increased at 24 h, reached their highest values at 48 h and began decreasing at 144 h, closely following the initial dynamics of SA concentration after each application. The spray application of SA in the absence of NaCl significantly increased the concentration of SA (up to 145 and 289% for the first and second application respectively) and CAT activity (up to 182% for the third application) in leaves, without affecting fruit yield. The application of SA in combination with 100 mM NaCl had the highest values of SA (up to 381 and 258% for the second and third application respectively) and CAT activity (up to 142 and 294% for the first and third application respectively), ​​without changing consistently the TAC of the leaves and without any effect on fruit production. The application of 100 mM NaCl did not affects the CAT activity, TAC or SA into the leaves, or fruit production.

Key words:  Plant stress tolerance, elicitors, salicylates, antioxidants.