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).