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| Titel |
New theories of root growth modelling |
| VerfasserIn |
Magdalena Landl, Andrea Schnepf, Jan Vanderborght, Katrin Huber, Mathieu Javaux, A. Glyn Bengough, Harry Vereecken |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250122497
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| Publikation (Nr.) |
 EGU/EGU2016-1544.pdf |
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| Zusammenfassung |
| In dynamic root architecture models, root growth is represented by moving root tips whose
line trajectory results in the creation of new root segments. Typically, the direction of root
growth is calculated as the vector sum of various direction-affecting components. However, in
our simulations this did not reproduce experimental observations of root growth in structured
soil. We therefore developed a new approach to predict the root growth direction.
In this approach we distinguish between, firstly, driving forces for root growth,
i.e. the force exerted by the root which points in the direction of the previous root
segment and gravitropism, and, secondly, the soil mechanical resistance to root
growth or penetration resistance. The latter can be anisotropic, i.e. depending on
the direction of growth, which leads to a difference between the direction of the
driving force and the direction of the root tip movement. Anisotropy of penetration
resistance can be caused either by microscale differences in soil structure or by
macroscale features, including macropores. Anisotropy at the microscale is neglected in
our model. To allow for this, we include a normally distributed random deflection
angle α to the force which points in the direction of the previous root segment with
zero mean and a standard deviation σ. The standard deviation σ is scaled, so that
the deflection from the original root tip location does not depend on the spatial
resolution of the root system model. Similarly to the water flow equation, the direction
of the root tip movement corresponds to the water flux vector while the driving
forces are related to the water potential gradient. The analogue of the hydraulic
conductivity tensor is the root penetrability tensor. It is determined by the inverse of soil
penetration resistance and describes the ease with which a root can penetrate the
soil.
By adapting the three dimensional soil and root water uptake model R-SWMS (Javaux et
al., 2008) in this way, we were able to simulate root growth and root water uptake in soil with
macropores. The model was parametrized using experimental results of studies by Hirth et al.
(2005) and Stirzaker et al. (1996). It proved to be capable of reproducing observed root
growth responses to structured soil both at the single root and the plant root system
scale.
This new approach enables us to investigate how plant roots use macropores to gain
access to water and nutrient reservoirs in deeper, highly dense soil layers.
Acknowledgements: Funding by German Research Foundation within the Research Unit
888 is gratefully acknowledged. The James Hutton Institute receives funding from the
Scottish Government. |
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