Patterns of size and fate relationships of contiguous organs in the apple (Malus domestica) crown

Abstract

In apple (Malus domestica), the size of a shoot and the vegetative or reproductive fate of the terminal bud on that shoot are considered to be related phenomena but with contrasted results depending on studies. Our hypothesis was that these relationships would be partly cultivar-dependent. Over a 3-yr period, the size relationships between shoots and fruit on two architecturally contrasted apple cultivars were assessed. For shoots, flowering frequency (dependent variable) was related to subtending shoot size (independent variable). Linear correlations were adjusted for size relationships between contiguous shoots in the same year (inflorescence vs bourse-shoot), and between years with differences in slopes and intercepts between the two cultivars. The relationships between the size of a shoot and flowering frequency differed between the two cultivars, with high flowering whatever shoot size vs parabolic relationships between the two variables, respectively. It is concluded that the relationships between shoot size and fate are cultivar-dependent. It is speculated that the flowering pattern not only depends on the property of the shoot alone, but also on the structural proportions of the parent branch and branching density. © New Phytologist (2004).