ABSTRACT
The depletion of conventional water resources, either due to a lack of precipitation or to pollution and the overexploitation of aquifers, has forced farmers to use lower-quality water. In many cases, this water contains high salt concentrations. Salinity is one of the abiotic stress factors that limit crop production. Plants have to activate different physiological, biochemical and molecular mechanisms in order to cope with salt stress. These mechanisms include changes in water relations, photosynthesis, respiration, hormone profiles, ion compartmentation, metabolism and gene expression. In addition to osmotic stress and ion toxicity constraints, salt stress also induces oxidative stress, contributing to the deleterious effects of salinity. In order to minimize the damaging effects of salt stress on plants, the use of plant biostimulants is recommended as one of the most innovative and promising solutions. Biostimulants are natural substances produced by plants themselves. These substances are capable of interacting with plant metabolism in order to improve responses to any type of stress, including stresses that threaten the plant’s survival. For these reasons, different studies have demonstrated that pre-treatments with various biostimulants such as humic acids, certain amino acids (such as proline and glycine-betaine), polyamines, H2O2, salicylic acid, and melatonin, in addition to the use of other strategies, such as the inoculation of arbuscular mycorrhizal fungi, can improve the plant response to salt stress. The aim of this chapter is to update our understanding of the effects of biostimulants on the alleviation of salt-induced damage in plants.
