Early seedling vigor is an essential trait of direct-seeded rice. It helps the seedlings to compete with weeds for water and nutrient availability, and contributes to better seedling establishment during the initial phase of crop growth. Seedling vigor is a complex trait, and phenotyping by a destructive method limits the improvement of this trait through traditional breeding. Hence, a non-invasive, rapid, and precise image-based phenotyping technique is developed to increase the possibility to improve early seedling vigor through breeding in rice and other field crops. To establish and assess the methodology using free-source software, early seedling vigor was estimated from images captured with a digital SLR camera in a non-destructive way. Here, the legitimacy and strength of the method have been proved through screening seven diverse rice cultivars varying for early seedling vigor. In the regression analysis, whole-plant area (WPA) estimated by destructive-flatbed scanner (WPAs) and non-destructive imaging (WPAi) approaches was strongly related (R2 > 83%) and suggested that WPAi can be adapted in place of destructive methods to estimate seedling vigor. In addition, this study has identified a set of new geometric traits (convex hull and top view area) for screening breeding lines for early seedling vigor in rice, which decreased the time by 80% and halved the cost of labor in data observation. The method demonstrated here is affordable and easy to establish as a phenotypic platform. It is suitable for most glasshouses/net houses for characterizing genotypes to understand the plasticity of shoots under a given environment at the seedling stage. The methodology explained in this experiment has been proven to be practical and suggested as a technique for researchers involved in direct-seeded rice. Consequently, it will help in the simultaneous screening of genotypes in large numbers, the identification of donors, and in gaining information on the genetic basis of the trait to design a breeding program for direct-seeded rice.

中文翻译：

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直播水稻早苗活力的无损表型分析

早苗活力是直播水稻的一个基本性状。它有助于幼苗与杂草竞争水分和养分供应，并有助于在作物生长的初始阶段更好地建立幼苗。幼苗活力是一个复杂的性状，通过破坏性方法进行表型分析限制了通过传统育种对该性状的改进。因此，开发了一种非侵入性、快速和精确的基于图像的表型技术，以增加通过水稻和其他大田作物育种提高早期幼苗活力的可能性。为了使用免费源软件建立和评估该方法，早期幼苗活力是根据数码单反相机以非破坏性方式拍摄的图像估计的。这里，通过对早苗活力不同的7个水稻品种的筛选，证明了该方法的合法性和有效性。在回归分估计幼苗活力的方法。此外，本研究确定了一套新的几何性状（凸包体和顶视图区域），用于筛选水稻早苗活力育种系，使数据观察时间缩短了80%，劳动力成本降低了一半。此处演示的方法价格合理且易于建立为表型平台。它适用于大多数温室/网房，用于表征基因型，以了解苗期在给定环境下芽的可塑性。该实验中解释的方法已被证明是实用的，并被建议为参与直播水稻的研究人员的一种技术。因此，它将有助于同时筛选大量基因型，识别供体，并获得有关性状遗传基础的信息，以设计直播水稻的育种计划。