Effect of floral differentiation on shoot morphology and consequences on canopy light interception and photosynthetic capacity based on 3D virtual plants

Floral differentiation modifies shoot morphology and then the relative frequency among shoot types within canopy which may affect canopy performance in apple.
This study aimed at comparing shoot morphological traits among shoot types and sensitivities of relative fractions among shoot types on canopy light interception and photosynthetic capacities in ‘Fuji’ and ‘Gala’ apple trees.
Shoots were distinguished according to length (long and short) and floral states (bourse, bourse shoots, and vegetative shoots). Apple canopies were digitized at the annual shoot scale and leaf scale for each shoot type and cultivar.
Three-dimensional virtual isolated shoots along a length gradient from 0.5 to 40 cm with the same axis spatial angle for each shoot type and cultivar and canopies for each cultivar were reconstructed based on allometric relationships and leaf angle distributions sampled at both shoot and leaf scales.
Light interception efficiency was estimated for all isolated virtual shoots.
The sensitivity of relative frequency of bourse and vegetative shoots on canopy light interception and photosynthetic capacities was investigated by in silico experiments.
Significant differences were detected among shoot types rather than between cultivars for shoot and leaf scale morphological traits.
Among shoot types, the vegetative long shoot (VL) had the highest shoot leaf area, followed by bourse long shoot (BL), vegetative short shoot (VS), bourse short shoot (BS), and bourse (BF) in this order.
The mean internode length of VL and BL was significantly higher than BS, VS, and BF. Moreover, vegetative shoots have a more horizontal orientation of leaves but lower isolated shoot light interception efficiency than bourse shoots, irrespective of shoot length and cultivar.
An increase of relative frequency of bourse shoots could improve canopy light interception efficiency and photosynthetic capacity, but the effects depended on cultivars and weather conditions.
The virtual plant will be helpful to optimize shoot demography resulting from floral differentiation within canopy, thus achieving a canopy with an efficient light interception.

XXXI International Horticultural Congress (IHC2022): International Symposium on Innovative Perennial Crops Management

Xiaoyun Zhang, Xilong Chen, Kai Wang, Xiuling Li, Ru Bai, Jianrong Feng, Baolong Zhao, E. Costes, Weiwei Yang

Malus domestica, vegetative shoot, bourse shoot, light interception, photosynthesis, digitizing, RATP

https://doi.org/10.17660/ActaHortic.2023.1366.41