Three-dimensional tree-digitalization for system analysis of apple orchards | Digitalisation tridimensionnelle des arbres pour l'analyse de systemes de vergers de pommier
2005
Potel, A.-M. | Monney, Ph. (Agroscope RAC Changins, Station federale de recherches agronomiques, Conthey (Switzerland). Centre d'arboriculture et d'horticulture des Fougeres) | Sinoquet, H. | Sonohat, G. | Lauri, P.-E.
Three groups of 6 13-years-old individual Golden Delicious trained in Vertical Axis, Drilling and Ycare were digitalized in 2004 and 2005 at the Centre des Fougères (VS, Switzerland) of Agroscope RAC Changins. Through a method of measurement developed by the INRA (Center of Clermont-Ferrand, France) it is possible to obtain an exact three-dimensional reproduction of the trees. Light is analysed with the STAR (Silhouette to Total Area Ratio) of each shoot, obtained by simulation, that characterizes precisely the distribution of the light in the tree. The results highlight the importance of the annual conditions in the evolution of the leaf area, characterised by partial biennal bearing in the second year. In 2004, light distribution was comparable in the three systems, while in 2005 the considerable increase of the leaf area due to the emergence of a great number of vegetative shoots caused differences between treatments. The localisation of these shoots (generally at the margins and at the top of the crowns) resulted in a bad distribution of the fruits along with an average reduction of 40% in the illumination of the generative shoots for the three systems. The illumination of the potential fructification points becomes insufficient when the leaf area index (LAI) exceeds 3, which was the case for all three systems in 2005. The value reached by the Drilling system was particularly high (LAI = 4,3) and the consequences of shading were particularly perceptible with a reduction of 53% of the generative shoots illumination.. The particularly marked biennal bearing marked by a concentration of the generative shoots inside the trees is not directly linked to the training system. This one, however, helps to explain the result.
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