Martins Adalvan D, O'Callaghan Felicity, Bengough A Glyn, Loades Kenneth W, Pasqual Moacir, Kolb Evelyne, Dupuy Lionel X
The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
Federal University of Lavras, CP 3037, Lavras, MG 37.200-000, Brazil.
New Phytol. 2020 Mar;225(6):2356-2367. doi: 10.1111/nph.16312. Epub 2019 Dec 12.
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.
根系生长受限源于克服土壤变形阻力所需的力。单个颗粒力的变化会影响根系发育，并常常使生长轨迹发生偏转。我们开发了透明土壤和光学投影断层扫描显微镜系统，可在一系列围压下的颗粒介质中获取生长轨迹和颗粒力的测量数据。我们开发了图像处理管道来分析根系轨迹模式，并建立了一种随机力学理论，以确定根系偏转与颗粒力以及根系增粗之间的关系。根系增粗可补偿平均颗粒力的增加，但无法阻止5%最极端的单个颗粒力导致根系偏转。偏转的幅度随压力增加，但它们会响应与向重力性相关的因素组装成波长守恒的螺旋。该研究揭示了在机械阻碍土壤条件下理解根系生长的机制，并提供了与抗旱作物育种相关的见解。
