Wang Xinyue, Ge Mengting, He Xueqing
College of Grassland Agriculture, Northwest A&F University, Yangling 712100, China.
Plants (Basel). 2025 Apr 18;14(8):1236. doi: 10.3390/plants14081236.
Drought stress is one of the key environmental factors restricting the germination of alfalfa seeds ( L.). Nanopriming is an innovative seed-priming technology able to meet economic, agronomic, and environmental needs in agriculture. However, the use of conventional nanomaterials is hampered by high costs, environmental risks, and biotoxicity. In this study, we synthesized iron oxide nanoparticles (FeONPs) using seasonal leaf extracts (collected from August to November) obtained via an enzymatic ultrasonic-assisted method. The synthesized FeONPs were characterized using SEM, EDS, DLS, FTIR, UV-Vis, and XRD. To investigate the effects of FeONP priming on alfalfa seed germination under drought stress, germination and pot experiments were conducted with five FeONP priming concentrations (unprimed, 0, 20, 40, and 60 mg/L) and three PEG-6000 concentrations (0%, 10%, and 15%) to simulate normal, moderate, and severe drought conditions. The results showed that leaf extracts collected in November exhibited the highest flavonoid content (12.8 mg/g), successfully yielding bioactive-capped spherical FeONPs with a particle size of 369.5 ± 100.6 nm. Germination experiments revealed that under severe drought stress (15% PEG-6000), the 40 mg/L FeONP treatment most effectively enhanced seed vigor, increasing the germination rate, vigor index, and α-amylase activity by 22.1%, 189.4%, and 35.5% ( < 0.05), respectively, compared to controls. Under moderate drought stress (10% PEG-6000), the 20 mg/L FeONP treatment optimally improved germination traits, increasing the germination rate by 25.5% and seedling elongation by 115.6%. The pot experiments demonstrated morphological adaptations in alfalfa seedlings: under moderate drought stress, the 40 mg/L FeONPs significantly increased lateral root numbers, while under severe drought stress, the 60 mg/L FeONPs increased the root surface area by 20.5% and preserved the roots' structural integrity compared to controls. These findings highlight that FeONPs synthesized via Ginkgo leaf extracts and enzymatic ultrasonic methods exhibit promising agricultural potential. The optimal FeONP priming concentrations enhanced seed vigor, germination traits, and drought resistance by modulating root morphology, with concentration-specific efficacy under varying drought intensities.
干旱胁迫是限制紫花苜蓿种子（紫花苜蓿）萌发的关键环境因素之一。纳米引发是一种创新的种子引发技术，能够满足农业中的经济、农艺和环境需求。然而，传统纳米材料的使用受到高成本、环境风险和生物毒性的阻碍。在本研究中，我们使用通过酶促超声辅助方法获得的季节性叶片提取物（8月至11月收集）合成了氧化铁纳米颗粒（FeONPs）。使用扫描电子显微镜（SEM）、能谱仪（EDS）、动态光散射（DLS）、傅里叶变换红外光谱（FTIR）、紫外可见光谱（UV-Vis）和X射线衍射（XRD）对合成的FeONPs进行了表征。为了研究FeONP引发对干旱胁迫下紫花苜蓿种子萌发的影响，进行了发芽和盆栽实验，设置了五个FeONP引发浓度（未引发、0、20、40和60 mg/L）和三个聚乙二醇-6000（PEG-6000）浓度（0%、10%和15%），以模拟正常、中度和重度干旱条件。结果表明，11月收集的叶片提取物黄酮含量最高（12.8 mg/g），成功制备出粒径为369.5±100.6 nm的具有生物活性包覆的球形FeONPs。发芽实验表明，在重度干旱胁迫（15% PEG-6000）下，40 mg/L FeONP处理最有效地提高了种子活力，与对照相比，发芽率、活力指数和α-淀粉酶活性分别提高了22.1%、189.4%和35.5%（P<0.05）。在中度干旱胁迫（10% PEG-6000）下，20 mg/L FeONP处理最佳地改善了发芽性状，发芽率提高了25.5%，幼苗伸长率提高了115.6%。盆栽实验证明了紫花苜蓿幼苗的形态适应性：在中度干旱胁迫下，40 mg/L FeONPs显著增加了侧根数，而在重度干旱胁迫下，60 mg/L FeONPs使根表面积增加了20.5%，并与对照相比保持了根系的结构完整性。这些发现突出表明，通过银杏叶提取物和酶促超声方法合成的FeONPs具有良好的农业应用潜力。最佳的FeONP引发浓度通过调节根系形态提高了种子活力、发芽性状和抗旱性，在不同干旱强度下具有浓度特异性效应。
