Doctoral thesis (Dissertations and theses)
Impact of spatio-temporal shade on crop growth and productivity, perspectives for temperate agroforestry
Artru, Sidonie
2017
 

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Abstract :
[en] Currently, silvoarable agroforestry is receiving renewed interest in Europe, as a land use system that allows for combining the production of commodities with a range of non-commodity outputs, such as environmental protection. Despite the potential of this practice, it remains rarely implemented in Northwestern Europe. One of the obstacles in the adoption of silvoarable agroforestry systems is the lack of quantitative knowledge on the long term performance of different crops when they are competing for resources with trees. In the face of a wide range of possibilities, it remains difficult to obtain a clear overview of overall system functioning. In this thesis, we simplify this complexity by focusing our research questions on the resource of light, based on the assumption that in Belgian climatic conditions light is likely to be the predominant constraint for understorey crops in a silvoarable agroforestry system. With regard to this resource, we develop our research in order to gain insights into the growth mechanisms and final yield of shaded winter wheat and sugar beet crops. We address these questions using an artificial shade system, which has been developed to reproduce the effect of the heterogeneous spatio-temporal pattern of light observed under late-flushing trees in an agroforestry system, isolated from the competition effects for water and nutrients. The shade structures recreate two shade environments: continuous and periodic. The continuous shade treatment leads to shade throughout the entire day, while the periodic shade treatment induces an intermittent shade period, which varies during the day and according to structure orientation. Winter wheat responded to the late application of both shade treatments with a significant decrease in grain yield, which was partly compensated for by an increase in grain protein content. When shaded, sugar beet compensated through morphological adaptations of the aboveground part of the plant, and by a decrease in the final root dry matter and sugar yield. Overall, for both crops, the magnitude of the final yield repercussion varied with the level and period of shade application. Additionally, an arable plot bordered by a row of poplar trees was selected to evaluate the effect of real trees on the winter wheat. The reduction in the final grain yield follows a gradient, from underneath the trees to the centre of the field. Notwithstanding that interactions other than light competition may have occurred, the maximum yield reduction observed under the trees never reaches the level of decrease which is observed under the continuous shade treatment simulated by the artificial shade arrangement. This experimental approach with winter wheat was complemented by a modelling study, in which we evaluate the ability of the STICS crop model to simulate crops growing under dynamic shade. The results highlight the limits of the STICS model when it is used to simulate crop growth under contrasted shade conditions. Finally, we propose agroecology as a conceptual framework for developing sustainable and profitable agroforestry systems in Europe, and reflect on agricultural practices, food systems, and research methodologies.
Disciplines :
Agriculture & agronomy
Author, co-author :
Artru, Sidonie ;  Université de Liège > Ingénierie des biosystèmes (Biose) > Gestion des ressources forestières et des milieux naturels
Language :
English
Title :
Impact of spatio-temporal shade on crop growth and productivity, perspectives for temperate agroforestry
Defense date :
06 June 2017
Institution :
ULiège - Université de Liège
Degree :
docteur en sciences agronomiques et ingénierie biologique
Promotor :
Garré, Sarah  ;  Université de Liège - ULiège > Département GxABT > Echanges Eau - Sol - Plantes
Lassois, Ludivine  ;  Université de Liège - ULiège > Faculté de Psychologie, Logopédie et Sciences de l'Education > CU cidépes
President :
Lejeune, Philippe ;  Université de Liège - ULiège > Département GxABT > Gestion des ressources forestières et des milieux naturels
Jury member :
Dumont, Benjamin  ;  Université de Liège - ULiège > Département GxABT > Plant Sciences
Ligot, Gauthier ;  Université de Liège - ULiège > TERRA Research Centre > Gestion des ressources forestières et des milieux naturels
Bodson, Bernard ;  Université de Liège - ULiège > Département GxABT
Dupraz, Christian
Reubens, Bert
Funders :
Agriculture Is Life, Université de Liège, Gembloux Agro-Bio Tech
Available on ORBi :
since 31 May 2017

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