Background Deep rooting is one of the most promising plant traits for improving crop yield under water-limited conditions. Most root phenotyping methods are designed for laboratory-grown plants, typically measuring very young plants not grown in soil and not allowing full development of the root system. Results This study introduced the 15N tracer method to detect genotypic variations of deep rooting and N uptake, and to support the minirhizotron method. The method was tested in a new semifield phenotyping facility on two genotypes of winter wheat, seven genotypes of spring barley and four genotypes of ryegrass grown along a drought stress gradient in four individual experiments. The 15N labeled fertilizer was applied at increasing soil depths from 0.4 to 1.8 m or from 0.7 to 2.8 m through a subsurface tracer supply system, and sampling of aboveground biomass was conducted to measure the 15N uptake. The results confirm that the 15N labeling system could identify the approximate extension of the root system. The results of 15N labeling as well as root measurements made by minirhizotrons showed rather high variation. However, in the spring barley experiment, we did find correlations between root observations and 15N uptake from the deepest part of the root zone. The labeled crop rows mostly had significantly higher 15N enrichment than their neighbor rows. Conclusion We concluded that the 15N tracer method is promising as a future method for deep root phenotyping because the method will be used for phenotyping for deep root function rather than deep root growth. With some modifications to the injection principle and sampling process to reduce measurement variability, we suggest that the 15N tracer method may be a useful tool for deep root phenotyping. The results demonstrated that the minirhizotrons observed roots of the tested rows rather than their neighboring rows.

中文翻译：

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测试深度放置 15N 示踪剂作为小麦、大麦和黑麦草原位深根表型分析的方法。

背景深生根是在水分有限的条件下提高作物产量的最有希望的植物性状之一。大多数根表型分析方法是为实验室种植的植物设计的，通常测量未在土壤中生长且不允许根系完全发育的非常年轻的植物。结果本研究引入15N示踪法检测深根性和N吸收的基因型变异，并支持minirhizotron方法。该方法在一个新的半田间表型分析设施中对两种冬小麦基因型、七种春大麦基因型和四种沿干旱胁迫梯度生长的黑麦草基因型进行了测试，在四个单独的实验中进行了测试。通过地下示踪剂供应系统，将 15N 标记的肥料施用于土壤深度从 0.4 到 1.8 m 或从 0.7 到 2.8 m，并对地上生物量进行采样以测量 15N 的吸收。结果证实15N标记系统可以识别根系的近似延伸。15N 标记的结果以及由微型根管进行的根测量显示出相当大的变化。然而，在春大麦实验中，我们确实发现了根系观察与根区最深处的 15N 吸收之间的相关性。标记的作物行大多比其相邻行具有显着更高的 15N 富集。结论 我们得出的结论是，15N 示踪法作为一种未来的深根表型分析方法是有前景的，因为该方法将用于表型分析，以了解深根功能而不是深根生长。通过对进样原理和采样过程进行一些修改以减少测量可变性，我们建议 15N 示踪方法可能是深根表型分析的有用工具。结果表明，微型根管菌观察的是被测行的根，而不是它们相邻的行。