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Characterization of mango tree patchiness using a tree-segmentation/clustering approach

Fernique P., Dambreville A., Durand J.B., Pradal C., Lauri P.E., Normand F., Guédon Y.. 2016. In : 2016 IEEE International Conference on Functional-Structural Plant Growth Modeling, Simulation, Visualization and Applications (FSPMA). Qingdao : IEEE, p. 68-74. IEEE International Conference on Functional-Structural Plant Growth Modeling, Simulation, Visualization and Applications (FSPMA 2016), 2016-11-07/2016-11-11, Qingdao (Chine).

DOI: 10.1109/FSPMA.2016.7818290

Research focus: Like many other tropical trees, mango tree is characterized by strong phenological asynchronisms between and within trees, entailing patchiness. Patchiness is characterized by clumps of either vegetative or reproductive growth units (GUs) within the canopy: while some parts of the tree canopy develop vegetative GUs, others may remain quiescent or produce inflorescences at the same time. These asynchronisms concern more or less large branching systems. The objective of this study was to define statistical methodology to identify and characterize patchiness patterns. Methods: Tree-indexed data are used as plant architecture representation and it is assumed that patches can be assimilated to a partition of tree-indexed data into subtrees. It is therefore assumed that there are subtrees within which the characteristics of the GUs follow the same or nearly the same distribution, and between which these characteristics have different distributions. The detection of such subtrees can thus be stated as tree-indexed data segmentation. The output of the segmentation procedure is a partition of trees such that two non-adjacent subtrees can be very similar in terms of GUs charateristics. We therefore propose in a second stage a clustering of subtrees based on a mixture model in order to group non-adjacent similar subtrees. This theoretical framework was applied to young mango trees that were fully described at the GU scale during two growing cycles. These trees were located in an experimental orchard of the CIRAD research station in Saint-Pierre, Réunion Island. Five mango trees were described for 7 cultivars, Cogshall, José, Kensington Pride, Irwin, Kent, Nam Doc Mai and Tommy Atkins. Results: The patches detected using the tree segmentation/clustering algorithm had various compositions and sizes. The empirical distributions of patch size (in number of GUs) were used to compare cultivar behaviours. Irwin had the largest patches, in contrast to Tommy Atkins that

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