Use of Exploratory Analysis for Recommendation of Seed Priming with Hydrogen Peroxide on Lettuce and Arugula Cultivated with Brackish Water

Hydrogen peroxide (H2O2) can act as a metabolic signal and induce increased tolerance of plants to various stresses. However, its use strategy and responsiveness may vary according to the species studied. Thus, this study aimed to evaluate the responses of lettuce and arugula crops to the use of H2O2 applied via seed with different strategies and to establish a recommendation for the use of this chemical conditioner to increase the tolerance of the studied crops. The seeds of both species were subjected to pretreatment with H2O2 at three concentrations (0.1, 1, and 10 mM) combined with three periods of exposure to H2O2 (12, 24, and 36 h) and, after this period, were subjected to salt stress of 50 mM NaCl in a hydroponic cultivation system. Additionally, two reference treatments were added: control (absence of H2O2 and absence of NaCl) and salt control (absence of H2O2 and 50 mM of NaCl). Our results showed that lettuce was more sensitive to salt stress than arugula. However, in general, the response to priming with H2O2 was less pronounced in arugula plants, suggesting that the increase in tolerance induced by the use of H2O2 in different plant species is associated with the genotypic characteristics of the species. For lettuce, the doses of 0.1 mM H2O2 (12 h) and 1 mM H2O2 (36 h) showed the best results of growth, while for arugula the best doses were 0.1 mM H2O2 (12 h) and 10 mM H2O2 (36 h).