Salicylic acid-mediated salt tolerance in date palms: comparative analysis of application methods

In arid environments, tree growth and ecosystem function are limited by salinity stress. Herein, we describe the role of salicylic acid (SA) in ameliorating salt tolerance in date palms (Phoenix dactylifera L., cv. Sayer), a woody species characteristic of arid, salinized environments. We examined the role of salicylic acid (SA) delivered via trunk injection and foliar treatment in the tree’s physiological acclimatization strategy. Trunk injection of SA at 200 ppm resulted in the highest plant height. SA treatments were associated with increased antioxidant activities (peroxidase and superoxide dismutase), decreased malondialdehyde, and fine-tuned hormone homeostasis (increased auxin and decreased abscisic acid). The trunk injection has much higher efficacy, providing important insights into the adaptation mechanisms of the tree and the efficacy of bioactive compound delivery from the injection site. Our results have implications for tree survival in increasingly salinized arid systems, and together, these findings represent progress toward a mechanistic understanding of ecophysiological pathways of adaptation to environmental stress in trees.