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The understanding of carbohydrate budgets in fruit trees made easy: what we know and ideas about what we need to know

DeJong, T. M.
Acta horticulturae 2017 no.1177 pp. 29-40
canopy, carbohydrates, environmental factors, fruit trees, growth and development, growth models, leaves, root growth, tree growth
For the past 30 years research in my laboratory has been largely concerned with understanding various aspects of carbohydrate assimilation and distribution in fruit trees. It is increasingly my belief that carbohydrate supply is the simpler side of the carbohydrate budget issue and under normal environmental conditions tree carbohydrate supply is simply a function canopy light interception. Understanding factors that dictate carbohydrate partitioning are more difficult to quantify but are conceptually also quite simple to understand since carbohydrate partitioning does not direct the growth of the tree but is the result of the growth and development of the organs that make up the tree. Quantifying carbohydrate partitioning in trees over time simply requires accurate estimations of seasonal organ growth potentials. Conceptually this is quite simple, but is complex in practice. To do this we chose to develop detailed models of seasonal organ growth and integrate them into a functional-structural tree growth model. This led to the development of submodels for fruit growth, leaf growth, shoot growth, root growth and carbohydrate storage capacity. With this approach even regulation of long-term carbohydrate storage in trees is much easier to understand than previously thought. In this paper I also outline what I believe could be interesting avenues for future research.