Dawson L A, Thornton B, Pratt S M, Paterson E
Soil Plant Microbial Interactions, The Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH, UK.
New Phytol. 2004 Mar;161(3):811-818. doi: 10.1111/j.1469-8137.2004.00979.x.
• This study examined morphological and topological responses of nodal root axes to defoliation in a fast- and a slow-growing grass species. • Vegetative tillers of both Lolium perenne and Festuca ovina were grown on slant boards and either left intact or subjected to repeated defoliation, under both a high nitrogen (N) and a low N supply. Root length, diameter and branching characteristics were measured on individual nodal root axes. • The total axis root length of F. ovina was less when plants had been defoliated. Root axis weight, primary root axis length and primary root diameter were also less with defoliation than an undefoliated control, under high N. Under low N conditions the root axes of F. ovina had a more randomly branched topology without defoliation. For L. perenne under low N conditions, the length of the primary root axis was longer with defoliation than in an undefoliated control, while the primary root axis diameter decreased. By contrast to F. ovina, the root axes of L. perenne had a more randomly branched topology without defoliation only when supplied with high N. • The greatest plasticity in branching caused by defoliation was observed under high N for L. perenne and under low N for F. ovina. Although grass root axis topology has, in general, a herringbone in structure, the nodal root system can alter root axis structure in response to defoliation.
• 本研究考察了快速生长和慢速生长的草种中节根轴对去叶处理的形态和拓扑响应。• 多年生黑麦草和羊茅的营养分蘖枝种植在倾斜板上，在高氮（N）和低氮供应条件下，分别保持完整或进行反复去叶处理。对单个节根轴的根长、直径和分支特征进行了测量。• 羊茅在去叶处理后，总轴根长度较短。在高氮条件下，去叶处理后的根轴重量、初生根轴长度和初生根直径也比未去叶的对照小。在低氮条件下，羊茅的根轴在未去叶时具有更随机的分支拓扑结构。在低氮条件下，多年生黑麦草去叶处理后的初生根轴长度比未去叶的对照长，而初生根轴直径减小。与羊茅相反，多年生黑麦草的根轴仅在高氮供应时未去叶时具有更随机的分支拓扑结构。• 在高氮条件下多年生黑麦草和低氮条件下羊茅的去叶处理导致的分支可塑性最大。尽管草的根轴拓扑结构总体上呈人字形，但节根系可响应去叶处理改变根轴结构。
