Simulation of carbon allocation and organ growth variability in apple tree by connecting architectural and source-sink models.
Plant growth depends on carbon availability and allocation among organs. QualiTree has been designed to simulate carbon allocation and partitioning in the peach tree (Prunus persica), whereas MappleT is dedicated to the simulation of apple tree (Malus × domestica) architecture. The objective of this study was to couple both models and adapt QualiTree to apple trees to simulate organ growth traits and their within-tree variability.



MappleT was used to generate architectures corresponding to the 'Fuji' cultivar, accounting for the variability within and among individuals. These architectures were input into QualiTree to simulate shoot and fruit growth during a growth cycle. We modified QualiTree to account for the observed shoot polymorphism in apple trees, i.e. different classes (long, medium and short) that were characterized by different growth function parameters. Model outputs were compared with observed 3D tree geometries, considering shoot and final fruit size and growth dynamics.



The modelling approach connecting MappleT and QualiTree was appropriate to the simulation of growth and architectural characteristics at the tree scale (plant leaf area, shoot number and types, fruit weight at harvest). At the shoot scale, mean fruit weight and its variability within trees was accurately simulated, whereas the model tended to overestimate individual shoot leaf area and underestimate its variability for each shoot type. Varying the parameter related to the intensity of carbon exchange between shoots revealed that behaviour intermediate between shoot autonomy and a common assimilate pool was required to properly simulate within-tree fruit growth variability. Moreover, the model correctly dealt with the crop load effect on organ growth.



This study provides understanding of the integration of shoot ontogenetic properties, carbon supply and transport between entities for simulating organ growth in trees. Further improvements regarding the integration of retroaction loops between carbon allocation and the resulting plant architecture are expected to allow multi-year simulations.
Institut National de la Recherche Agronomique (INRA), UMR 1334 AGAP, CIRAD-INRA-Montpellier SupAgro, F-34398 Montpellier, France, pallas@supagro.inra.fr.
Benoît
B
Pallas
Institut National de la Recherche Agronomique (INRA), UMR 1334 AGAP, CIRAD-INRA-Montpellier SupAgro, F-34398 Montpellier, France.
David
D
Da Silva
INRA, UR 1115 Plantes et Systèmes de Culture Horticoles, F-84914 Avignon, France and.
Pierre
P
Valsesia
College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China.
Weiwei
W
Yang
Institut National de la Recherche Agronomique (INRA), UMR 1334 AGAP, CIRAD-INRA-Montpellier SupAgro, F-34398 Montpellier, France.
Olivier
O
Guillaume
Institut National de la Recherche Agronomique (INRA), UMR 1334 AGAP, CIRAD-INRA-Montpellier SupAgro, F-34398 Montpellier, France.
Pierre-Eric
PE
Lauri
INRA, UR 1115 Plantes et Systèmes de Culture Horticoles, F-84914 Avignon, France and.
Gilles
G
Vercambre
INRA, UR 1115 Plantes et Systèmes de Culture Horticoles, F-84914 Avignon, France and.
Michel
M
Génard
Institut National de la Recherche Agronomique (INRA), UMR 1334 AGAP, CIRAD-INRA-Montpellier SupAgro, F-34398 Montpellier, France.
Evelyne
E
Costes
D001692:Biological Transport; D050260:Carbohydrate Metabolism; D002244:Carbon / Q000378:metabolism*; D003198:Computer Simulation; D005638:Fruit / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D027845:Malus / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D008954:Models, Biological; D018515:Plant Leaves / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D014197:Trees
D002244:Carbon
Carbohydrate allocation; Malus ×; domestica; functional structural plant models; organ growth; shoot autonomy