Current infrared spectroscopy applications in the field of viticulture are moving toward direct in-field measuring techniques. However, limited research is available on quantitative applications using direct measurement of fresh tissue. The few studies conducted have combined the spectral data from various cultivars, growing regions, grapevine organs, and phenological stages during model development. The spectral data from these heterogeneous samples are combined into a single data set and analyzed jointly during quantitative analysis. Combining the spectral information of these diverse samples into a global data set could be an unsuitable approach and could yield less accurate prediction results. Spectral differences among samples could be overlooked during model development and quantitative analysis. The development of specialized calibrations should be considered and could lead to more accurate quantitative analyses. This study explored a model optimization strategy attempting global and specialized calibrations. Global calibrations, containing data from multiple organs, berry phenological, and shoot lignification stages, were compared to specialized calibrations per organ or stage. The global calibration for organs contained data from shoots, leaves, and berries and produced moderately accurate prediction results for nitrogen, carbon, and hydrogen. The specialized calibrations per organ yielded more accurate calibrations with a coefficient of determination in validation (R2val) at 90.65% and a root mean square error of prediction (RMSEP) at 0.32% dry matter (DM) for the berries’ carbon calibrations. The leaves and shoots carbon calibrations had R2val and RMSEP at 84.99%, 0.34% DM, and 90.06%, 0.37% DM, respectively. The specialized calibrations for nitrogen and hydrogen showed similar improvements in prediction accuracy per organ. Specialized calibrations per phenological and lignification stage were also explored. Not all stages showed improvement, however, most stages had comparable or improved results for the specialized calibrations compared to the global calibrations containing all phenological or lignification stages. The results indicated that both global and specialized calibrations should be considered during model development to optimize prediction accuracy.

中文翻译：

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探索用于量化葡萄器官、浆果物候阶段和芽木质化营养成分的全球和专业近红外校准

当前红外光谱在葡萄栽培领域的应用正朝着直接现场测量技术的方向发展。然而，对于直接测量新鲜组织的定量应用的研究有限。进行的少数研究结合了模型开发过程中不同品种、种植区域、葡萄器官和物候阶段的光谱数据。来自这些异质样品的光谱数据被组合成一个数据集，并在定量分析过程中联合分析。将这些不同样本的光谱信息组合到全局数据集中可能是一种不合适的方法，并且可能会产生不太准确的预测结果。在模型开发和定量分析过程中，样品之间的光谱差异可能会被忽略。应考虑开发专门的校准，这可以带来更准确的定量分析。本研究探索了一种尝试全局和专门校准的模型优化策略。将包含来自多个器官、浆果物候和芽木质化阶段的数据的全局校准与每个器官或阶段的专门校准进行比较。器官的全局校准包含来自芽、叶和浆果的数据，并对氮、碳和氢产生了中等准确的预测结果。每个器官的专门校准产生了更准确的校准，并具有验证中的确定系数（R2val）为 90.65%，预测均方根误差（RMSEP）为 0.32% 干物质（DM），用于浆果的碳校准。叶子和芽的碳校准有 R2val 和 RMSEP 分别为 84.99%、0.34% DM 和 90.06%、0.37% DM。对氮和氢的专门校准显示每个器官的预测精度都有类似的提高。还探索了每个物候和木质化阶段的专门校准。并非所有阶段都显示出改进，但是，与包含所有物候或木质化阶段的全局校准相比，大多数阶段的专门校准具有可比较或改进的结果。结果表明，在模型开发过程中应考虑全局校准和专业校准，以优化预测精度。