This study investigated the growth regulation mechanism of quercetin on seed germination and seedling growth of Apocynum venetum L. under salt stress， and determined its optimal application concentration. This study utilized A. venetum as the experimental material， and established eight treatments： HCKN： 200 mmol·L^-1 NaCl salt stress； Q₁+N-Q₆+N： 200 mmol·L^-1 NaCl +50， 100， 150， 200， 250， 300 μmol·L^-1 quercetin）. The study systematically measured seed germination traits （germination rate， germination vigor， germination index）， seedling growth indicators （plant height， root growth parameters， biomass， leaf growth parameters）， photosynthetic physiological traits （photosynthetic pigment content， chlorophyll fluorescence parameters）， and stress resistance physiological indicators （antioxidant enzyme activity， malondialdehyde content， proline content）. The alleviation effects were comprehensively evaluated using the membership function method. The results indicated that salt stress had a minor effect on the germination rate of A. venetum seeds but significantly reduced germination vigor and germination index. It severely inhibited the growth of A. venetum seedlings and impaired photosynthetic system function， characterized by significantly decreasing photosynthetic pigment content and PSII photochemical efficiency， along with increasing accumulation of malondialdehyde， a lipid peroxidation product.The salt stress-alleviating effect of quercetin exhibited a pronounced concentration-dependent response： Low quercetin concentrations （Q₁+N， Q₂+N） provided limited alleviation， while high concentrations （Q₅+N， Q₆+N） failed to effectively improve growth and even inhibited A. venetum seedling development. Compared to other quercetin concentration treatments， the 150 μmol·L^-1 quercetin （Q₃+N） treatment showed the best salt stress alleviation effect. Compared to the salt-stressed control （HCKN）， it increased seed germination potential and germination index by 2.1% and 3.5%， respectively. Seedling height increased by 97.2%， total chlorophyll content and carotenoid content increased by 17.1% and34.9% respectively， proline content increased by 20.6%， and malondialdehyde content decreased by 22.8% （P<0.05）. Concurrently， it significantly improved root morphology and chlorophyll fluorescence parameters， bringing seedling growth and physiological characteristics closer to the normal control level. Quercetin enhances salt tolerance in A. venetum seedlings by synergistically promoting photosynthetic pigment synthesis， strengthening antioxidant system function， regulating osmotic balance， and optimizing root structure， thereby effectively mitigating salt stress damage. This study identifies the optimal concentration and key physiological mechanisms by which quercetin regulates A. venetum’s salt tolerance， providing crucial technical guidance for large-scale cultivation and ecological restoration of A. venetum in saline-alkali soils.

Quercetin  /  Apocynum venetum L.  /  Salt stress  /  Seed germination  /  Seedling growth