The development and utilization of saline-alkali land is a key focus for grassland improvement in China， and enhancing the germination capacity of native grass seeds is a crucial step of this process. In this study seeds of Mongolian wheatgrass （Agropyron mongolicum） was used as the material to investigate the effects of nano-iron particle suspensions at different concentrations （25， 50， 75 and 100 mg·L^-1） and different priming duration （4 h and 36 h） on seeds germination， seedling growth characteristics and antioxidant enzyme activities of seedling under 175 mmol·L^-1 mixed salt solution stress （NaCl∶Na₂SO₄=5∶1）. Multispectral imaging technology was also used to rapidly and visually assess seedling vigor and to screen for the most salt-tolerant priming treatments. The results showed that the priming treatment with 4 h significantly outperformed than the 36 h treatment according to the analysis of seed germination and seedling growth indexes （P<0.05）. Nano-iron priming for 4 h at all concentrations significantly improved the germination percentage and germination index （P<0.05）， reduced mean germination time， and increased seedling height， fresh weight， vigor index， and antioxidant enzyme activities （e.g. POD， CAT， APX and MDHAR） in the seedlings （P<0.05）. The nCDA images from multispectral imaging were highly consistent with the trends of these physiological and biochemical changes. Among all the treatments， 50 mg·L^-1 nano-iron priming for 4 h was the most effective， significantly enhancing germinability and growth performance of Mongolian wheatgrass under salt stress and markedly improving its salt tolerance. These findings provide important scientific evidence for vegetation restoration and ecological rehabilitation in saline-alkali lands.

Mongolian wheatgrass  /  Salt tolerance  /  Seed priming  /  Nano-iron