To elucidate the adaptive capacity of Cyperus esculentus to salt-alkali stress and clarify the synergistic effects of salt and alkali， a two-factor completely randomized design was employed using ‘Zhongyousha 1’ as the test material. Compound salt-alkali stress was imposed using six salt gradients （0， 100， 150， 200， 250， and 300 mmol·L^-1 Na⁺） and three alkali gradients （pH 7.0， 8.5， and 10.0）. Seed germination， seedling growth， leaf osmolytes， and antioxidant parameters were determined under these conditions. The results showed that germination percentage， fresh weight， and seedling length decreased significantly with increasing salt stress （P<0.05）. Notably， the lethal salt threshold under strong alkali conditions （250 mmol·L^-1） was lower than that in neutral and weak alkali environments （300 mmol·L^-1）. With intensifying stress， seedlings mitigated damage by accumulating proline， soluble sugars， and soluble proteins for osmotic adjustment， and by enhancing peroxidase and catalase activities. In conclusion， Cyperus esculentus adapted to salt-alkali stress by regulating osmotic and antioxidant capacities； however， excessive salt and alkali levels exceed its tolerance threshold， causing irreversible damage. These findings provide a scientific basis for promoting the cultivation of Cyperus esculentus in saline-alkali lands in Xinjiang.

Cyperus esculentus  /  Saline-alkali stress  /  Seedling growth  /  Leaf osmotic adjustment  /  Antioxidant capacity