Root Tip Shape Governs Root Elongation Rate under Increased Soil Strength
Root Tip Shape Governs Root Elongation Rate under Increased Soil Strength
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DOI：
10.1104/pp.17.00357
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发表时间：
2017-08-01
期刊：
影响因子：
7.4
通讯作者：
Keller, Thomas
中科院分区：
文献类型：
--
作者：
Colombi, Tino;Kirchgessner, Norbert;Keller, Thomas
由于土壤压实或土壤干燥而增加的土壤强度是对根系生长和作物生产力的主要限制。根部需要施加更高的渗透力，从而导致在强度更大的土壤中伸长时渗透应力增加。本研究旨在量化根尖几何形状和根直径的基因型多样性如何影响根伸长在不同水平的土壤强度，并确定在何种程度上根调整增加土壤强度。14个小麦（Triticum aestivum）品种种植在土柱填充到三个容重代表低，中，高土壤强度。在中等强度和高强度土壤条件下，较小的根尖径长比与较高的基因型根伸长速率相关，而根径与基因型根伸长无关。基于空穴膨胀理论，发现较小的根尖径长比降低了穿透应力，从而使更高的根伸长速率在土壤中具有更大的强度。此外，据观察，根系只能部分适应土壤强度的增加。根增厚的最大直径为界，根尖并没有成为更尖锐的土壤强度增加。结果表明，在强度较大的土壤中，根尖的几何形状是决定根系穿透应力和根伸长速率的关键性状。因此，在选择可能耐受高土壤强度的作物品种时，需要考虑根尖形状。
Increased soil strength due to soil compaction or soil drying is a major limitation to root growth and crop productivity. Roots need to exert higher penetration force, resulting in increased penetration stress when elongating in soils of greater strength. This study aimed to quantify how the genotypic diversity of root tip geometry and root diameter influences root elongation under different levels of soil strength and to determine the extent to which roots adjust to increased soil strength. Fourteen wheat (Triticum aestivum) varieties were grown in soil columns packed to three bulk densities representing low, moderate, and high soil strength. Under moderate and high soil strength, smaller root tip radius-to-length ratio was correlated with higher genotypic root elongation rate, whereas root diameter was not related to genotypic root elongation. Based on cavity expansion theory, it was found that smaller root tip radius-to-length ratio reduced penetration stress, thus enabling higher root elongation rates in soils with greater strength. Furthermore, it was observed that roots could only partially adjust to increased soil strength. Root thickening was bounded by a maximum diameter, and root tips did not become more acute in response to increased soil strength. The obtained results demonstrated that root tip geometry is a pivotal trait governing root penetration stress and root elongation rate in soils of greater strength. Hence, root tip shape needs to be taken into account when selecting for crop varieties that may tolerate high soil strength.