Effect of seed priming on germination of Hesperochloa sinensis : Implications for the restoration of the Qinghai-Tibet Plateau

Hesperochloa sinensis is a widely distributed alpine native grass on the Qinghai-Tibetan Plateau. As a wild species, low seed vigour limits its application in grassland restoration. Seed priming is a useful method for improving seed quality, but its effectiveness in H. sinensis remains poorly studied. This study evaluated the effects of five priming treatments, spermidine (SPD), glutathione (GSH), polyethylene glycol (PEG), carbon quantum dots (CQDs) and hydropriming (HP), on seed germination and seedling vigour, and their physiological basis. All priming treatments, including HP, enhanced germination performance and seedling vigour. Treatment effectiveness were ranked as follows: 50 mg L ^-1 CQDs > HP > 0.05 mM GSH > 0.5 mM SPD > −0.8 MPa PEG > unprimed control. CQDs priming exhibited the strongest effect, increasing CAT, POD and SOD activities by 35.6%, 42.7% and 152%, respectively, compared with non-primed seeds. It also promoted accumulation of soluble sugars, total protein and proline. Together, these findings suggest that seed priming, particularly CQDs priming, is a promising strategy for enhancing early seedling establishment of H. sinensis , with potential to contribute to alpine grassland restoration.