Trade-off between radial trunk growth and fruit yield and its relationship to xylem traits in composite apple and pear trees

Understanding the issue of how plants divide limited carbon (C) resources among various competing functions is the key aim in plant ecophysiology, and it is also of paramount importance in the sphere of agriculture and forestry. In the case of trees, C acquisition and allocation are tightly linked with the structure and functions of the wood. However, these relationships are not sufficiently understood. To address this issue, our project will disentangle the C allocation priorities into the radial trunk growth and fruit yield (G-Y trade-off), and then it will elucidate how the strength of the G-Y trade-off depends on the hydraulic and storage functions of the xylem and its construction costs as well. Our studies will make 41 composite tree variants involved. Specifically, the domestic apple and European pear that differ in radial growth vigour and susceptibility to alternate bearing will be studied. The G-Y trade-off will be analysed at two temporal scales using long-term chronologies and a source-sink manipulation experiment. The results will develop our fundamental understanding of carbon allocation and xylem functioning in trees, and they are also expected to be valuable in the sphere of fruit tree cultivation and management.