ABSTRACT The reflectance spectra of vegetation carry potentially useful information that can be used to determine chemical composition and discriminate between vegetation classes. If compared with analytical methods such as conventional chemical analysis, reflectance measurement provides non-destructive, economic, near real-time data. This paper reports results from reflectance measurements performed by spectroradiometry on leaves and branches of Vitis vinifera L. cv. Merlot and Cabernet Sauvignon from two vineyards in south Brazil. The vineyards had different geological origins but were subjected to the same management. The objectives were to detect spectral differences between the vineyards, and to correlate these differences to variations in foliar traits like the chemical composition of vine leaves. To that end, seven vine parcels were selected for reflectance measurements and chemical analyses (of eleven elements) of vine leaves, and correlations between reflectance and chemical composition were looked for. An initial investigation by discriminant analysis applied to reflectance data of leaves and branches and to grape varieties as well allowed for good separation between vineyards and varieties (> 90% accuracy). By further investigating the correlations between leaf chemical composition and reflectance along the wavelength domain covered by the measurements, we found several well-determined wavelengths with Pearson correlation coefficients r > 0.7. Concentrations of elements could be modelled up to 94% accuracy. These preliminary results, which have to be validated, suggest that variations in soil properties induce chemical differences in vine leaves that can be detected by reflectance measurements. Applications of this observation include the assessment of the chemical content of vine leaves by spectroradiometry as a fast, low-cost alternative to chemical analytical methods.

中文翻译：

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矿物质含量对藤叶光谱特征的影响

摘要 植被的反射光谱带有潜在有用的信息，可用于确定化学成分和区分植被类别。与传统化学分析等分析方法相比，反射率测量可提供无损、经济、近乎实时的数据。本文报告了通过光谱辐射测定法对 Vitis vinifera L. cv. 的叶子和树枝进行反射率测量的结果。来自巴西南部两个葡萄园的梅洛和赤霞珠。葡萄园有不同的地质起源，但受到相同的管理。目标是检测葡萄园之间的光谱差异，并将这些差异与叶性状的变化（如藤叶的化学成分）相关联。为此，选择了七个藤块进行藤叶的反射率测量和化学分析（十一种元素），并寻找反射率和化学成分之间的相关性。通过判别分析的初步调查适用于叶子和树枝的反射数据以及葡萄品种，并允许葡萄园和品种之间的良好分离（> 90% 准确度）。通过进一步研究叶片化学成分与测量所涵盖的波长域反射率之间的相关性，我们发现了几个确定的波长，其 Pearson 相关系数 r > 0.7。元素浓度的建模准确率高达 94%。这些必须验证的初步结果，表明土壤性质的变化会导致藤叶的化学差异，这可以通过反射率测量来检测。这种观察的应用包括通过光谱辐射测定法评估藤叶的化学成分，作为化学分析方法的一种快速、低成本的替代方法。