Limitation to root growth results from forces required to overcome soil resistance to deformation. The variations in individual particle forces affects root development and often deflects the growth trajectory. We have developed transparent soil and optical projection tomography microscopy systems where measurements of growth trajectory and particle forces can be acquired in a granular medium at a range of confining pressures. We developed image-processing pipelines to analyse patterns in root trajectories and a stochastic-mechanical theory to establish how root deflections relate to particle forces and thickening of the root. Root thickening compensates for the increase in mean particle forces but does not prevent deflections from 5% of most extreme individual particle forces causing root deflection. The magnitude of deflections increases with pressure but they assemble into helices of conserved wavelength in response linked to gravitropism. The study reveals mechanisms for the understanding of root growth in mechanically impeding soil conditions and provides insights relevant to breeding of drought-resistant crops.

中文翻译：

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根部的螺旋运动与避免土壤中的粒子力有关。

根系生长的限制是由克服土壤抗变形能力所需的力引起的。各个粒子力的变化会影响根系发育，并经常使生长轨迹发生偏移。我们已经开发了透明的土壤和光学投影层析成像显微系统，可以在一定范围的限制压力下在粒状介质中获得生长轨迹和颗粒力的测量结果。我们开发了图像处理管道来分析根轨迹中的模式，并建立了随机力学理论来确定根偏斜如何与粒子力和根的增厚相关。根部加厚可以补偿平均粒子力的增加，但不能防止导致根部偏斜的最极端单个粒子力的5％产生偏斜。挠度随压力的增加而增加，但由于与重力有关，它们会组装成守恒波长的螺旋。这项研究揭示了理解机械障碍土壤条件下根系生长的机制，并提供了与抗旱作物育种有关的见识。