Impact of autochthonous biostimulants on bioactive compounds of date palm vitroplants under salt stress

In arid and semi-arid areas, the date palm (Phoenix dactylifera L.), plays an important socio-economic role. Nevertheless, in recent years, the whole world has been subject to severe climate change, which is having a negative impact on plant growth, physiology and production, particularly through increased soil and water salinity. The present study was carried out to evaluate the response of date palm vitroplants to salinity and examine the possible roles of a native and exotic arbuscular mycorrhizal fungus (AMF1 and AMF2, respectively), plant growth-promoting rhizobacteria (PGPR) and compost in improving salt tolerance. Plants were grown under non-saline and saline conditions (0 and 300 mM NaCl) with and without application of the tested biostimulants alone or in dual or in triple combination. Plant growth parameters, including plant height and plant dry biomass, were negatively affected by salinity. However, plants treated with biostimulants showed higher growth parameters and greater biosynthesis of bioactive compounds such as total polyphenols and flavonoids concentration under saline conditions, compared to the untreated plants. In addition, salt stress caused high lipid peroxidation and increased hydrogen peroxide (H2O2) concentration. However, the application of biostimulants reduced both parameters in salt-affected plants. The best reductions in stress markers (malondialdehyde MDA and H2O2) 57% and 55% and 51% and 49% were recorded in plants treated respectively with the two triple combinations PGPR + AMF1 + Comp and PGPR + AMF2 + Comp. Lastly, the results indicated the application of biostimulants and especially their combination as an efficient practice to improve growth and development of date palm. © The Author(s) under exclusive licence to Society for Plant Research 2024.