Progress in Whole-Tree Architectural Studies for Apple Cultivar Characterization at INRA, France - Contribution to the Ideotype Approach

In France, the determination of fruiting type and tree ideotype has been a first step in the description of the variability of the whole-tree shape in relation to fruiting behaviour. Although the ranking into four ideotypes gives an easy-to-use criterion to discriminate between cultivars, it does not clearly address the various strategies of growth, branching and fruiting among apple cultivars. Over the last decade, detailed architectural investigations have been developed at trunk and branch levels. Both frequencies and spatial distribution of (i) types (vegetative sylleptic or proleptic, flowering, latent); and (ii) length of laterals (spur, long shoot) on 1-year old wood and during further development have been shown to follow specific patterns depending on the cultivar. This paper will discuss the interest of these architectural analyses for cultivar characterization with the objective to provide the apple breeder with an apple tree ideotype for low-input regular-bearing cultivar.