Articles
Photosynthetic capacity in ‘Fuji’ apple trees influenced by interstocks at leaf and canopy scale
Article number
1261_14
Pages
77 – 84
Language
English
Abstract
Canopy photosynthetic capacity depends not only on leaf scale photosynthetic capacity but also on growing conditions, such as the rootstock or interstock, which affects the canopy structure.
The interstock effect on photosynthetic capacity has not been well elucidated.
This study aimed at comparing the photosynthesic performance of Fuji apple trees at leaf and canopy scale and when grafted on a vigorous rootstock, associated with either a dwarf interstock (VD) or a vigorous interstock (VV). Six VD trees and four VV trees were digitized to build three-dimensional virtual canopies.
Leaf stomatal conductance (gs), net photosynthesis rate (A), and dark respiration (Rd) were measured during summer, and parameters of Farquhars and Jarvis models were estimated at leaf scale.
These parameters and the virtual trees along with measured meteorological data were used as inputs of the RATP functional-structural model, to estimate the photosynthetic capacity at canopy scale.
At leaf scale, using the leaf nitrogen content per unit leaf area (Na) as covariate, we showed the significant effect of interstocks on the maximum carboxylation rate (Vcmax) and on Rd, but not on the maximum electron transport rate (Jmax). Gs had similar responses to photosynthetically active radiation, leaf temperature, and vapour pressure deficit, but the relative gs was higher in VV than VD trees.
At leaf scale, mean A was 17% higher in VV than in VD trees.
However, at canopy scale the inverse was observed, with a net photosynthesis rate of 60% higher in VD than in VV trees (129.80 and 82.23 mmol CO2 m-2 day-1 on average for VD and VV trees, respectively). These results imply that VD decreased A at leaf scale, but this was compensated at canopy scale, likely due to more uniformed leaf spatial distribution (Yang et al., 2016). They emphasize the divergence of evaluation scales and highlight the importance of the leaf spatial distribution on leaf functions and tree performance.
The interstock effect on photosynthetic capacity has not been well elucidated.
This study aimed at comparing the photosynthesic performance of Fuji apple trees at leaf and canopy scale and when grafted on a vigorous rootstock, associated with either a dwarf interstock (VD) or a vigorous interstock (VV). Six VD trees and four VV trees were digitized to build three-dimensional virtual canopies.
Leaf stomatal conductance (gs), net photosynthesis rate (A), and dark respiration (Rd) were measured during summer, and parameters of Farquhars and Jarvis models were estimated at leaf scale.
These parameters and the virtual trees along with measured meteorological data were used as inputs of the RATP functional-structural model, to estimate the photosynthetic capacity at canopy scale.
At leaf scale, using the leaf nitrogen content per unit leaf area (Na) as covariate, we showed the significant effect of interstocks on the maximum carboxylation rate (Vcmax) and on Rd, but not on the maximum electron transport rate (Jmax). Gs had similar responses to photosynthetically active radiation, leaf temperature, and vapour pressure deficit, but the relative gs was higher in VV than VD trees.
At leaf scale, mean A was 17% higher in VV than in VD trees.
However, at canopy scale the inverse was observed, with a net photosynthesis rate of 60% higher in VD than in VV trees (129.80 and 82.23 mmol CO2 m-2 day-1 on average for VD and VV trees, respectively). These results imply that VD decreased A at leaf scale, but this was compensated at canopy scale, likely due to more uniformed leaf spatial distribution (Yang et al., 2016). They emphasize the divergence of evaluation scales and highlight the importance of the leaf spatial distribution on leaf functions and tree performance.
Publication
Authors
Weiwei Yang, Xiaoyun Zhang, M. Saudreau, Dong Zhang, E. Costes, Mingyu Han
Keywords
Malus domestica, leaf nitrogen, digitizing, photosynthesis, interstock, RATP, functional-structural plant model
Groups involved
Online Articles (39)