Induced salinity tolerance and altered ion storage factor in Hordeum vulgare plants upon salicylic-acid priming

This study was undertaken to better understand the probable mechanisms of salt stress tolerance induced by seed priming of salicylic acid (SA) in barley. The barley seeds were pre-soaked by SA or water and then sown under different saline watering regimes including 0.62 (tapwater), 5, 10 and 15 dS m-1 in petri dishes and trend of water absorbing, seedling growth, germination rate and percentage were measured. After 11 days, seedlings were transplanted to pots and K and Na accumulation and storage factor were determined. The results showed that salt stress reduced absorbed water (50%), germination rate (39%), seedling growth (74%) and K accumulation (38%) and increased Na accumulation (fivefold). In all hours after sowing, SA-primed seeds had greater absorbed water with higher growth rate and this trend was true for all days after sowing. SA-primed seedlings had higher germination rate (30%), as well as, shoot (17%) and root length (38%). Enhanced K and reduced Na accumulation was also found in SA-primed seedlings. Reduction in Na absorption due to SA application was found to be greater at lower salinity stress levels and this was consistent with its effect on seedling growth. Storage factor, devised for quantifying partitioning of absorbed ions, were found to be increased for K and decreased for Na at higher salt stress levels; this means that at higher salinity levels, greater Na and lower K were transported to the shoot and this was associated with greater loss in seedling growth. Indeed, SA-primed seedlings showed a greater Na storage factor i.e. they kept more Na in their roots, in non- and light salt stress treatments. Accelerated water imbibition, greater germination rate, less Na, higher K accumulation, and greater Na storage in roots might be some mechanisms for salt stress tolerance in SA-primed barley seedlings.