USING COMPUTER TECHNOLOGY TO STUDY, UNDERSTAND AND TEACH HOW TREES GROW

Studying and understanding fruit tree growth and development is a difficult endeavor. Plants are very complex organisms that are governed and influenced by a multitude of factors. In the past our ability to study and integrate plant function has been largely limited to only dealing with a couple factors at a time and communicating those interactions verbally or with two dimensional diagrams. The subject of studying and understanding carbon partitioning in plants is a good example of this limitation. Modeling carbon partitioning is a complex problem because of the dynamic nature and relationships between carbohydrate partitioning, growth and plant architecture. Until recently there have been no fruit tree simulation models that have attempted to quantitatively model these three processes simultaneously. The L-PEACH model is an attempt to develop a detailed model of tree carbon economy in which growth and function of each organ is modeled individually within an architecturally explicit model of canopy growth. L-PEACH combines the supply/demand concepts of carbon allocation of the previous PEACH model with an L-systems model of tree architecture to create a distributed supply/demand system of carbon allocation in a three dimensional, growing tree. The L-PEACH plant model is expressed in terms of modules that represent plant organs. An organ is represented as one or more elementary sources or sinks for carbohydrates and the whole plant is modeled as a branching network of these sources and sinks, connected by conductive elements. An analogy to an electrical network is used to calculate the flow and partitioning of carbohydrates between the individual components. The model can be used to simulate how crop load, rate of fruit maturity, storage tissue sink capacity, and/or water stress can influence growth and carbohydrate partitioning within a fruit tree.