Root System Development of Oak Seedlings Analysed using an Architectural Model. Effects of Competition with Grass |
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Authors: | Catherine Collet Magnus Löf Loïc Pagès |
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Institution: | (1) LERFoB, INRA, 54280 Champenoux, France;(2) SLU, Southern Swedish Forest Research Centre, P.O. Box 49, 23053 Alnarp, Sweden;(3) Unité PSH, INRA, Site Agroparc, 84914 Avignon, Cedex 9, France |
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Abstract: | A dynamic 3D model of root system development was adapted to young sessile oak seedlings, in order to evaluate the effects
of grass competition on seedling root system development. The model is based on a root typology and the implementation of
a series of developmental processes (axial and radial growth, branching, reiteration, decay and abscission). Parameters describing
the different processes are estimated for each root type. Young oak seedlings were grown for 4 years in bare soil or with
grass competition and were periodically excavated for root system observation and measurements (topology of the root system,
length and diameter of all roots with a diameter greater than 0.3 mm). In the fourth year, 40 cm×20 cm×20 cm soil monoliths
were excavated for fine root measurement (root density and root length). Root spatial development was analysed on a sub-sample
of roots selected on four seedlings. The model was a guideline that provided a complete and consistent set of parameters to
represent root system development. It gave a comprehensive view of the root systems and made it possible to quantify the effects
of competition on the different root growth processes. The same root typology was used to describe the seedlings in bare soil
and in grass. Five root types were defined, from large tap roots to fine roots. Root system size was considerably reduced
by grass competition. Branching density was not affected but the branch roots were always smaller for the seedlings grown
in competition. Reiteration capacity was also reduced by competition. Cross sectional areas before and after branching were
linearly related with a scaling coefficient close to 1, as predicted by the pipe model theory. This relationship was not affected
by grass competition. |
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Keywords: | competition Quercus petraea radial growth reiteration root architecture model root typology |
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