Research Overview & Publications

Summary of Fruit Tree Physiology/Pomology Research in the DeJong Lab

Since joining the Department of Pomology (later merged into the Department of Plant Sciences) at UC Davis in 1981 my research program has mainly focused on understanding tree physiological and orchard management factors that control the carbon balance/budgets of fruit and nut trees. Initial work focused on understanding the functioning and photosynthetic efficiencies of tree leaves1 and understanding factors governing the horticultural efficiencies of orchard canopies. Because of previous research on the interactions between photosynthesis and nitrogen dynamics in legumes much of this research was simultaneously focused on understanding of the dynamics of nitrogen partitioning within tree canopies.

As I gained experience and understanding of factors controlling the “supply side” of the carbon balance equation later studies focused on the “demand side” of the equation and the integration of both aspects into a functional understanding the how tree carbon budgets work. This “demand side” work focused on characterization and understanding factors governing flowering and fruit set, fruit growth, vegetative (leaf and shoot) growth and root growth and eventually involved numerous studies characterizing how rootstocks control shoot growth. Much of my intellectual stimulation for conducting the various aspects of this research came from an overall goal of developing integrated understanding of fruit tree carbon budgets and growth through crop modeling. This led to the development of very sophisticated and complex functional-structural tree simulation models that are not only carbon budget models but also include integrated understanding of architectural development and spur dynamics of fruit trees. Demonstrative simulations of the L-Peach tree growth simulation model are available at

In addition to this physiological research I have also been the principle investigator on a prune breeding project since 1985. The Californian prune industry is currently dependent on a single cultivar. The goal of this project is the development of new prune/dried plum cultivars for the Californian industry that will increase orchard and processing efficiencies, spread the harvest season and maintain or increase dried product quality.

All of the research publications that I have co-authored are presented in two lists. The first list mainly contains papers that were peer-reviewed and are referred to as Category I papers. The second list contains Conference papers and are referred to as Category II papers. Links to copies of most of these papers are available as PDF Documents in two corresponding lists.

I have attempted to categorize these research publications into the focus areas highlighted above. Since this is a post-hoc categorization some of the publications fit into more than one category. Papers that did not fit into any of these specific categories are listed under Miscellaneous research topics. Most of my research was conducted on peach. Work on other crop species are also listed separately.

Links to Publication Listings by Category

Newly released:

Concepts for Understanding Fruit Trees

Available from CABI
Available on Amazon