Seed biopriming of durum wheat with purified and combined halotolerant bacteria improved seed germination under salinity conditions

Background and aim: Improved crop productivity under stressful conditions is a major asset of global agriculture. Salinity is one of the most severe abiotic stresses limiting crop yield. Further, a salt-affected area in Tunisia is fast escalating due to intrusion of saline water on arable land and the use of chemical fertilizers and pesticides. Moreover, climate change scenarios showed the increased risk of salinization at different latitudes. Therefore, a great effort is required for maintaining crop production under limiting factors. The present study was conducted to isolate and identify PGPB associated with the halophyte Salicornia brachiata from the coastal saline sites and evaluation their bacterization effect of durum wheat seeds with “Biopriming” technology.

Methods: The selection parameters of PGPB strains were based on the ability to promote the growth of plants under stressful conditions. On the other hand, the effect of selected isolates on germination of durum wheat (Triticum durum) was assessed in vivo conditions. The treatment with bacteria was applied on purified and combined strain under 25 and 125 mM NaCl.

Results: A total of 22 isolates were selected in-vitro for studying their plant growth-promoting (PGPB) ability including, tolerance with salt concentration, ACC deaminase activity, N₂ fixation, phosphorus solubilization, and indole-3-acetic acid (IAA), out of which, three strains (MA9, MA32, and SA62) were selected. Our data revealed that experiments using treated with NaCl and bioprimed seed permitted us to identify the most efficient isolates in a combined culture which offered the best rate of germination and the highly vegetable growth of explants (roots and shoots). In fact, the benefic effect of seed biopriming was more pronounced in samples added with NaCl than that of untreated samples.

Conclusion: Seed biopriming with efficient PGPB strains induced salinity tolerance of wheat and therefore enhanced their rate of germination under salinity.