The application of salicylic acid minimizes the deleterious effects of water deficit in tomato through metabolic and ABA adjustments

Tomato is an important horticultural crop that is adversely affected by water deficit. However, the deleterious effects of water deficiency can be mitigated through the application of salicylic acid (SA). While SA works as a critical signaling molecule in stress mitigation, abscisic acid (ABA) is another key phytohormone involved in regulation plant responses to abiotic stress. The interaction between SA and ABA is complex and often antagonistic, particularly in the modulation of stress signaling pathways. In this context, the study aimed to evaluate the application of SA as a mitigating agent for water deficit in tomato plants. Two independent experiments were conducted, one in 2019 and the other in 2020, with three treatments: control (100 % crop evapotranspiration (ETc) (well-watered), 70 % ETc (drought), and 70 % ETc (drought) + 1.0 mM SA application. The analyzed variables included gas exchange, chlorophyll fluorescence a, total soluble sugars content, proline, abscisic acid, and fruit weight. The application of SA contributed to the maintenance of photosynthetic metabolism, acting mainly on stomatal conductance and CO2 assimilation, while also reducing photooxidative damage and the production of reactive oxygen species in plants under water stress. Additionally, SA favored osmoregulation in stressed plants. Therefore, SA acted as a mitigating agent against water deficit in tomato plants, and the application of 1.0 mM of SA was sufficient to attenuate damage. Theses findings suggest that salicylic acid may be a promising strategy for mitigate the damage caused by water stress in tomato crops.