Impact of Salicylic and Jasmonic Acid in Mitigating Salinity Stress on Date Palm Phoenix dactylifera L. Barhi Cv.

Date palm is one of the most important trees for economic and social development in many countries and its fruits with high nutritional value. This aimed to determine the role of salicylic (SA) and jasmonic acids (JA) as antioxidants against salt stress. Salt stress was applied with water irrigation to two-year-old date palm offshoots by using 200 mM NaCl alone or in combination with foliar sprays of JA and SA at 1, 2 and 3 mgL-1. Results indicate that salinity at 200 mM NaCl remarkably increased the content of osmolytes (e.g., proline, glycine betaine and soluble sugars) in date palm leaves. Moreover, with the combination of 2 and 3 mg.L-1 SA and 1 mg.L-1 JA with salinity, the osmolyte content was remarkably higher than in salinity treatment alone. When date palm was exposed to salinity alone, the levels of oxidative markers, Malondialdehyde as a lipid peroxidation marker and H2O2 as a ROS accumulation marker, substantially increased compared with the control. Importantly, the levels of these oxidative markers remarkably decreased when plants were subjected to combined salinity and treatment with at 2 and 3 mg.L-1 SA and 3 mg.L-1 SA compared with the salinity treatment alone. In addition, spraying 2 and 3 mg.L-1 SA and 3 mg.L-1 JA on leaves combined with salinity treatment remarkably decreased the salinity effect on membrane stability index. Moreover, when 2 or 3 mg.L-1 were sprayed, no remarkable difference was detected for any investigated characteristics, and SA had a greater effect than JA in alleviating the salinity effect.