A supply and demand approach to modeling annual reproductive and vegetative growth of deciduous fruit trees.

and odel. 35C umed pply An approach to developing a simulation model of the annu supply and demand for reproductive and vegetative growth in p trees is presented. This modeling approach simulates photosynth assimilation using seasonal canopy light interception and daily m mum and maximum temperature and solar radiation inputs. Sim ing C partitioning and crop growth is based on the hypothesis plants grow as collections of semi-autonomous, but interacting gans. The plant genotype, triggered by internal and environm signals, determines current organ-specific growth potentials. D environmental conditions interact with organ-specific growth po tials to determine the conditional growth capacity and mainten respiration requirement (i.e., the daily C demand) of each organ Then, the daily C available for growth after maintenance requirem are met is partitioned to leaves, fruit, stems, and branches bas their relative conditional growth capacities. Remaining carbohyd is partitioned to the trunk, based on its conditional growth capa and all residual carbohydrate is partitioned to roots after abovegr demands are met. The methods used to determine organ-sp growth potentials and the usefulness of using the supply and de approach to modeling the C economy of deciduous fruit crops discussed. The relatively intensive management requirements of pere horticultural crops probably offer more opportunities for pract applications of computer simulation models of crop growth carbohydrate requirements than less intensively managed ann biennial agronomic crops. However, there has been much less res on models for perennial horticultural crops than for annual