Benefits of Silicon on Plant Tolerance to Stress from Signaling with Phytohormones

Silicon (Si) is a non-essential element. However, it plays a crucial role in plant growth and productivity. Its application activates defense mechanisms, involving the modulation of hormones under biotic and abiotic stresses. In turn, plant hormones (auxins, gibberellins, cytokinins, ethylene, abscisic acid, brassinosteroids, jasmonates, salicylic acid, and strigolactones) contribute to coordinate several processes, including adaptation to biotic and abiotic stresses. The objective of this chapter is to present information on the interaction between the use of Si to alleviate abiotic and biotic stresses and modulation of plant hormones. Except of strigolactones, the interaction with Si is already established for other hormones under abiotic stresses (drought; salinity; cadmium, copper, ammonium, and arsenic toxicity; potassium, sulfur, and iron deficiency; chilling; heat; high pH; and submergence) and biotic stresses (mildew; brown spot fungus; bacterial wilt; pink stem borer; chewing herbivores; late blight; and anthracnose and clubroot disease). This chapter provides a comprehensive overview of hormonal regulation in relation to stress tolerance induced by Si application.