Abstract Foliar application of nutrient fertilizers is standard practice in agricultural environments, and has been shown to increase crop yield and quality more efficiently and economically than soil-based fertilizers. The adsorption of macro- and micro-nutrients through the upper epidermis of leaves is largely species dependent; reliant upon penetration through the cuticle and stomata, and also upon the plant’s ability to translocate the nutrient. Herein we describe a method to observe nitrate (NO3−) uptake at the adaxial leaf surface to determine the efficacy of foliar fertilizers. We use Raman microspectroscopy as a sensitive approach to monitor NO3− associated vibrational modes, complemented by ion probe measurements and measurements of leaf nutrient status using flame atomic absorption spectroscopy. The results show that NO3− uptake can be observed down to concentrations as low as 15 mM using Raman microspectroscopy over a defined surface area, and that the rate of uptake can also be quantified using this approach. These observations could also infer information regarding the transport of other ions present in nitrate salts, such as calcium (Ca), via the indirect monitoring of NO3- specific bands. We believe that Raman microspectroscopy provides a novel method for monitoring nutrient movement throughout plant tissue, and provides a potential tool for nutrient screening.

中文翻译：

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使用拉曼光谱观察番茄 (Solanum lycopersicum) 叶片正面养分吸收

摘要 叶面施用营养肥料是农业环境中的标准做法，并且已被证明比土壤肥料更有效、更经济地提高作物产量和质量。通过叶子的上表皮吸收大量和微量营养素在很大程度上取决于物种。依赖于穿透角质层和气孔，也依赖于植物转移养分的能力。在本文中，我们描述了一种观察近轴叶表面硝酸盐 (NO3−) 吸收的方法，以确定叶面肥料的功效。我们使用拉曼显微光谱作为监测 NO3− 相关振动模式的灵敏方法，辅以离子探针测量和使用火焰原子吸收光谱测量叶片营养状态。结果表明，使用拉曼显微光谱法在定义的表面积上可以观察到低至 15 mM 的 NO3- 吸收，并且也可以使用这种方法量化吸收率。这些观察结果还可以通过对 NO3 特异性波段的间接监测来推断有关硝酸盐中存在的其他离子（例如钙 (Ca)）的传输的信息。我们相信拉曼显微光谱提供了一种监测植物组织中养分运动的新方法，并提供了一种潜在的养分筛选工具。这些观察结果还可以通过对 NO3 特异性波段的间接监测来推断有关硝酸盐中存在的其他离子（例如钙 (Ca)）的传输的信息。我们相信拉曼显微光谱提供了一种监测植物组织中养分运动的新方法，并提供了一种潜在的养分筛选工具。这些观察结果还可以通过对 NO3 特异性波段的间接监测来推断有关硝酸盐中存在的其他离子（例如钙 (Ca)）的传输的信息。我们相信拉曼显微光谱提供了一种监测植物组织中养分运动的新方法，并提供了一种潜在的养分筛选工具。