Walnuts are grown worldwide in temperate areas and producers are facing an increasing demand. In a climate change context, the industry also needs cultivars that provide fruits of quality. This quality includes satisfactory filling ratio, thicker shell, ease of cracking, smooth shell and round-shaped walnut, and larger nut size. These desirable traits have been analysed so far using calipers or micrometers, but it takes a lot of time and requires the destruction of the sample. A challenge to take up is to develop an accurate, fast and non-destructive method for quality-related and morphometric trait measurements of walnuts, that are used to characterize new cultivars or collections in any germplasm management process. In this study, we develop a method to measure different morphological traits on several walnuts simultaneously such as morphometric traits (nut length, nut face and profile diameters), traits that previously required opening the nut (shell thickness, kernel volume and filling kernel/nut ratio) and traits that previously were difficult to quantify (shell rugosity, nut sphericity, nut surface area and nut shape). These measurements were obtained from reconstructed 3D images acquired by X-ray computed tomography (CT). A workflow was created including several steps: noise elimination, walnut individualization, properties extraction and quantification of the different parts of the fruit. This method was applied to characterize 50 walnuts of a part of the INRAE walnut germplasm collection made of 161 unique accessions, obtained from the 2018 harvest. Our results indicate that 50 walnuts are sufficient to phenotype the fruit quality of one accession using X-ray CT and to find correlations between the morphometric traits. Our imaging workflow is suitable for any walnut size or shape and provides new and more accurate measurements. The fast and accurate measurement of quantitative traits is of utmost importance to conduct quantitative genetic analyses or cultivar characterization. Our imaging workflow is well adapted for accurate phenotypic characterization of a various range of traits and could be easily applied to other important nut crops.

中文翻译：

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使用 X 射线计算机断层扫描对核桃形态特征进行 3D 表征。

核桃在全球温带地区种植，生产商面临着日益增长的需求。在气候变化的背景下，该行业还需要提供优质果实的品种。这种品质包括令人满意的填充率、较厚的壳、易于开裂、光滑的壳和圆形核桃以及较大的坚果尺寸。到目前为止，已经使用卡尺或千分尺分析了这些理想的特征，但这需要大量时间并且需要破坏样品。面临的一个挑战是开发一种准确、快速和无损的方法，用于核桃的质量相关和形态特征测量，用于在任何种质管理过程中表征新品种或新品种。在这项研究中，我们开发了一种方法来同时测量几个核桃的不同形态特征，例如形态特征（坚果长度、坚果面和轮廓直径）、以前需要打开坚果的特征（壳厚度、核体积和填充核/坚果比）和特征以前很难量化（壳皱褶度、坚果球形度、坚果表面积和坚果形状）。这些测量是从通过 X 射线计算机断层扫描 (CT) 获得的重建 3D 图像中获得的。创建了一个工作流程，包括几个步骤：噪声消除、核桃个性化、特性提取和水果不同部分的量化。该方法用于鉴定 INRAE 核桃种质资源集中的 50 个核桃，该收集由 2018 年收获的 161 个独特种质组成。我们的结果表明，50 颗核桃足以使用 X 射线 CT 对一个种质的果实品质进行表型分析，并找到形态特征之间的相关性。我们的成像工作流程适用于任何尺寸或形状的胡桃木，并提供新的、更准确的测量结果。数量性状的快速准确测量对于进行数量遗传分析或品种表征至关重要。我们的成像工作流程非常适合对各种性状进行准确的表型表征，并且可以轻松应用于其他重要的坚果作物。我们的成像工作流程适用于任何尺寸或形状的胡桃木，并提供新的、更准确的测量结果。数量性状的快速准确测量对于进行数量遗传分析或品种表征至关重要。我们的成像工作流程非常适合对各种性状进行准确的表型表征，并且可以轻松应用于其他重要的坚果作物。我们的成像工作流程适用于任何尺寸或形状的胡桃木，并提供新的、更准确的测量结果。数量性状的快速准确测量对于进行数量遗传分析或品种表征至关重要。我们的成像工作流程非常适合对各种性状进行准确的表型表征，并且可以轻松应用于其他重要的坚果作物。