Simulation of shoot and fruit growth in apple

Modeling approaches which reveal how a plant allocates carbohydrates to the different organs are of major interest since carbohydrate allocation determines many growth processes. In this study, Pallas et al. describe a modeling approach allowing the simulation of carbohydrate allocation and organ growth in apple trees by coupling two models, MappleT and QualiTree.

Schematic representation of the procedure used to convert multiscale tree graphs (MTGs) generated by MappleT into QualiTree architecture in a simplified example. (A) MTG generated by MappleT and represented at the growth unit (GU) scale. (B) Conversion of the MTG into QualiTree architecture described at the production unit scale. S, M, L and I refer to short, medium, long and inflorescence GUs, respectively. (C) Schematic representation of the plant in MappleT. (D) Schematic representation of the plant in QualiTree. The numbers in C refer to the GU label. Image from Pallas *et al*. (2016)

The coupled model was appropriate to simulate growth characteristics at the tree and organ scales. This modeling approach shows the necessity of accurately simulating the impact of distances between sources and sinks as well as shoot ontogenetic characteristics, in order to represent the observed growth variability within tree architecture.