Effect of Salicylic Acid in Inhibiting Fungal Contamination in in vitro Cultures of Date Palm (Phoenix dactylifera L.) and Enhancing Embryogenesis and Plantlet Development

In this study, we evaluated the role of salicylic acid in diminishing fungal contamination in in vitro cultures of date palm and the effect of salicylic acid on the regeneration of somatic embryos from callus formed on shoot tips. The most prevalent fungi were Alternaria alternata (37%), Fusarium solani (25%), Aspergillus fumigatus (18%), and Penicillium expansum (6%). Salicylic acid limited and at higher concentrations retarded mycelial growth using potato dextrose agar. Salicylic acid at concentrations of 1.5 and 2.0 mM added to MS medium with 2iP and NAA significantly increased the embryogenesis rate of calli explants to 64.9% and 56.7%, respectively, compared with the control (12.3%). Salicylic acid also increased plantlet development from embryos by about 27% compared with the control. Salicylic acid caused better shoot and root growth and increased chlorophyll content. The results showed that the addition of salicylic acid at 1.5 mM to the MS medium resulted in a significant increase in the concentrations of IAA and ABA, as well as a decrease in the concentration of IBA in leaves.