A SUPPLY AND DEMAND APPROACH TO MODELING ANNUAL REPRODUCTIVE AND VEGETATIVE GROWTH OF DECIDUOUS FRUIT TREES

Abstract

An approach to developing a simulation model of the annual carbon supply and demand for reproductive and vegetative growth in peach trees will be presented. This modeling approach simulates photosynhetic carbon assimilation using seasonal canopy light interception and daily minimum and maximum temperature and solar radiation inputs. Simulation of carbon partitioning and crop growth is based on the hypothesis that plants grow as collections of semi-autonomous, but interacting organs. The plant genotype, triggered by internal and environmental signals, determines current organ specific growth potentials. Daily environmental conditions interact with organ specific growth potentials to determine the conditional growth capacity and maintenance respiration requirement (i.e. the carbon demand) of each organ type. Then the daily carbon available for growth after maintenance requirements are met is partitioned to leaves, fruits, stems, and branches based on their relative conditional growth capacities. Remaining carbohydrate is partitioned to the trunk based on its conditional growth capacity and all residual carbohydrate is partitioned to roots after above-ground demands are met. The methods used to determine organ specific growth potentials and the usefulness of using the supply and demand approach to modeling the carbon economy of deciduous fruit crops will be discussed.