外源褪黑素对NaCl胁迫下向日葵种子萌发的影响

盐胁迫是影响作物产量和质量的非生物胁迫之一，褪黑素能有效提高植物应对盐胁迫的水平。本文以矮生向日葵为研究对象，以筛选出的0.25mol/LNaCl为胁迫浓度，通过测定种子萌发指标、膜脂过氧化程度、渗透调节物质含量和抗氧化酶活性等，研究外源褪黑素对盐胁迫下向日葵种子萌发的生理调控机制。结果表明：随着褪黑素浓度的增加，种子的发芽势、发芽率、发芽指数、可溶性蛋白质含量均呈先升后降趋势，其中25μmol/L的效果最佳。脯氨酸含量较对照不断增长，以100μmol/L的效果最佳。MDA含量较对照减少，以25μmol/L的抑制作用最为显著。不同浓度外源褪黑素对种子SOD、POD和CAT活力均有明显的增加，以25μmol/L的效果最为显著。综上所述，25μmol/L褪黑素可以作为向日葵种子萌发期对抗NaCl胁迫的有效预处理措施，本研究为褪黑素的利用和向日葵栽培调控提供依据。

Effects of Exogenous Melatonin on Helianthus annuus L.Under NaCl Stress

Salt stress is one of the abiotic stresses that affect crop yield and quality. Melatonin can effectively enhance a plant’s response to salt stress. In this study, Helianthus annuus L. was chosen as the subject, and a stress concentration of 0.25 mol/L NaCl was selected. The physiological regulation mechanism of exogenous melatonin on sunflower seed germination under salt stress was investigated by assessing seed germination index, membrane lipid peroxidation degree, osmotic adjustment substance content, and antioxidant enzyme activity. The results showed that with the increase of melatonin concentration, the germination potential, germination rate, germination index, and soluble protein content of seeds increased first and then decreased, with the optimal concentration at 25 μmol/L. The proline content increased compared with the control, with the optimal effect at 100 μmol/L. The content of MDA decreased compared with the control, and the inhibitory effect of 25 μmol/L was the most significant. Different concentrations of exogenous melatonin significantly increased the activities of SOD, POD, and CAT in seeds, with the most significant effect at 25 μmol/L. In summary, 25 μmol/L melatonin can be used as an effective pretreatment measure for sunflower seed germination under NaCl stress. This study lays a foundation for the utilization of melatonin and the regulation of Helianthus annuus L. cultivation.