Use of mycorrhizal fungi in improving tolerance of the date palm (Phoenix dactylifera L.) seedlings to salt stress

摘要

The current study was carried out to assess the response of date palm (Phoenix dactylifera L.) to salinity and to examine the possible role of arbuscular mycorrhizal fungi (AMF) in enhancing the salt tolerance. Plants were grown under non-saline or saline conditions (0 and 240 mM NaCl) with and without AMF inoculation while biochemical, mineral as well as growth parameters were measured in this study. Plant growth parameters including plant height, leaf area and shoot and root dry weight were negatively affected by salinity. However, mycorrhizal plants showed higher growth parameters under saline condition compared to non inoculated salt-affected plants, although root colonization by AMF structures was reduced by salinity. Mycorrhiza mitigated the decrease of K, P and Ca content induced by salinity. Ca/Na and K/Na ratios were also improved in colonized plants. Otherwise, AMF symbiosis improved physiological parameters through elevating stomatal conductance, photosynthetic efficiency and leaf water potential under salinity stress. In the same conditions, mycorrhizal inoculation significantly enhanced concentrations of photosynthetic pigments and protein content. Furthermore, salt stress caused high lipid peroxidation and increased H2O2 content; however, the application of AMF reduced these two parameters in salt-affected plants while activities of antioxidant enzymes (superoxide dismutase, catalase, peroxidase and ascorbate peroxidase) were increased by salt stress and were further enhanced in plants treated with AMF. Overall, it is evident that soil salinity induced detrimental effects on date palm plants, which were lower in mycorrhizal plants than in the non-mycorrhizal ones. In conclusion, colonization with AMF may protect date palm seedlings against the negative salinity influence by mitigating the salt induced oxidative stress.