Dorien J. Vanhees, Kenneth W. Loades, Glyn A. Bengough, Sacha J. Mooney, Jonathan P. Lynch


Journal of Experimental Botany, 71(14):4243-4257

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To better understand the role of root anatomy in regulating plant adaptation to soil mechanical impedance, 12 maize lines were evaluated in two soils with and without compaction treatments under field conditions. Penetrometer resistance was 1 to 2 MPa greater in the surface 30 cm of the compacted plots at water content of 17-20% (v/v). Root thickening in response to compaction varied among genotypes and was negatively associated with rooting depth at one field site under non-compacted plots. Thickening was not associated with rooting depth on compacted plots. Genotypic variation in root anatomy was related with rooting depth. Deeper-rooting plants were associated with reduced cortical cell file number in combination with greater mid cortical cell area for node 3 roots. For node 4, roots with increased aerenchyma had deeper roots. A greater influence of anatomy on root depth was observed for the thinner root classes. We found no evidence that root thickening is related to deeper rooting in compacted soil however anatomical traits are important, especially for thinner root classes.