Development of non-destructive measuring systems for root growth based on AE method

植物根系发育的连续测量对于评估其对水分和养分吸收的贡献以及对土壤环境变化的响应具有重要意义。然而，目前还没有一种方法可以对土壤中的根系进行连续测量。通过这项研究，我们开发了一种利用声发射（AE）传感器测量土壤中空间根系伸长的新方法。声发射被定义为“从破坏和/或变形的材料中以声脉冲的形式释放能量的现象”。我们试图检测土壤颗粒与生长中的根碰撞时产生的声发射脉冲，以推断根是如何发育的。这些传感器以15mm的间隔垂直放置在矩形不锈钢容器（15*14*200mm）的四个侧壁上。空间根尖位置由三个轴表示。在同一平面和相对平面上的三个传感器获得的x和y轴上的相对声发射计数与根尖在x和y轴上的位置呈线性相关。根尖在X轴和Y轴上的位置(X)由方程Y=0.740-0.042 2x （r=0.861^<****>）计算得到，该方程通过对实际测量的根尖位置的相对声发射计数(Y)进行回归得到。因此，可以随时估计空间根尖位置。声发射传感器估算的玉米主根尖位置轨迹与实测结果基本一致。这种方法可以对根尖的位置和生长方向进行连续的三维测量。可以检测到大范围的根伸长率和方向角。

Continuous measurement of plant root development is important for evaluating its contributions to water and nutrient uptake, as well as is responses to changes in the soil environment. However, there has been no method to measure the root system continuously in soil.Through this study, we have developed a new non-destructive method for measurements of spatial root elongation in soil, using Acoustic Emission (AE) sensors. AE is defined as "the phenomenon of the energy, which is released, as sound pulses, from destroyed and/or deformed materials". We tried to detect AE pulses generated in the collisions between soil particles and a growing root in order to deduce how roots are developing.There sensors were placed vertically at 15mm intervals on each of thefour side walls of a rectangular stainless steel container (15*14*200mm). Spatial root tip position was expressed by the three axs. Relative AE counts on x and y-axis, obtained from three sensors on the same and oppsite planes, were linearly related to root tip position on x and y-axis. Root tip positions (X) on the x and y-axis can be calculated from the equation Y=0.740-0.042X (r=0.861^<****>) which was developed by regressing relative AE counts (Y) on actual measurements of root tip position. Thus spatial root tip position can be estimated at any time. The trajectory of maize primary root tip postion estimated by AE sensors was almost consistent with that obtained from actual measurements. This method can be used to give continuous, three-dimensional measurement of root tip position and direction of growth. A wide range of root elongation rates and direction angles can be detected.