Integrating simulation of architectural development and source-sink behaviour of peach trees by incorporating Markov chains and physiological organ function submodels into L-PEACH

Abstract : L-PEACH is an L-system-based functional-structural model for simulating architectural growth and carbohydrate partitioning among individual organs in peach ( Prunus persica (L.) Batsch) trees. The original model provided a prototype for how tree architecture and carbon economy could be integrated but did not simulate peach tree architecture realistically. Moreover, evaluation of the functional characteristics of the individual organs and the whole-tree remained a lar gely open issue. In this work we incorporated Markovian models into L-PEACH in order to improve the architecture of simulated trees. The model was also calibrated to g rams of carbohydrate, and tools for systematically displaying quantitative outputs and evaluating the behaviour of the model were developed. The use of the Markovian model conc ept to model tree architecture in L- PEACH reproduced tree behavior and responses to man agement practices visually similar to trees in commercial orchards. The new architectu ral model along with a number of improvements in the carbohydrate partitioning algor ithms derived from the model evaluation significantly improved results related t o carbon allocation, such as organ growth, carbohydrate assimilation, reserve dynamics , and maintenance respiration. The model results are now consistent within the modelle d tree structure and are in general agreement with observations of peach trees growing under field conditions.