Light interception and partitioning between shoots in apple cultivars influenced by training
Jean Stephan (1), Hervé Sinoquet (1, 2), Nicolas Donès (1), Nicolas Haddad (3), Salma Talhouk (3) and Pierre-Éric Lauri (4)
1. UMR547 PIAF, INRA, Univ Blaise Pascal, F-63100 Clermont Ferrand, France / 2. Corresponding author () / 3. Faculty of Agricultural and Food Sciences, American University of Beirut, Riad El Solh 1107 2020, P.O. Box 11-0236, Beirut,
Lebanon / 4. UMR DAP, INRA-SUPAGRO-CIRAD-UM II, Equipe ‘Architecture et Fonctionnement des Espèces Fruitières’, 2 place Viala, 34060, Montpellier,
Cedex 1, France / Received May 15, 2007; accepted September 20, 2007; published online January 2, 2008
Summary
The effect of two training systems (Central Leader with branch pruning versus Centrifugal Training with minimal pruning, i.e.,
removal of fruiting laterals only) on canopy structure and light interception was analyzed in three architecturally contrasting
apple (Malus domestica Borkh.) cultivars: ‘Scarletspur Delicious’ (Type II); ‘Golden Delicious’ (Type III); and ‘Granny Smith’ (Type IV). Trees
were 3D-digitized at the shoot scale at the 2004 and 2005 harvests. Shoots were separated according to length (short versus
long) and type (fruiting versus vegetative). Leaf area density (LAD) and its relative variance (ξ), total leaf area (TLA)
and crown volume (V) varied consistently with cultivar. ‘Scarletspur Delicious’ had higher LAD and ξ and lower TLA and V compared with the other cultivars with more open canopies. At the whole-tree scale, training had no effect on structure and
light interception parameters (silhouette to total area ratio, STAR; projected leaf area, PLA). At the shoot scale, Centrifugal
Training increased STAR values compared with Central Leader. In both training systems, vegetative shoots had higher STAR values
than fruiting shoots. However, vegetative and fruiting shoots had similar TLA and PLA in Centrifugal Trained trees, whereas
vegetative shoots had higher TLA and PLA than fruiting shoots in Central Leader trees. This unbalanced distribution of leaf
area and light interception between shoot types in Central Leader trees partly resulted from the high proportion of long vegetative
shoots that developed from latent buds. These shoots developed in the interior shaded zone of the canopy and therefore had
low STAR and PLA. In conclusion, training may greatly affect the development and spatial positioning of shoots, which in turn
significantly affects light interception by fruiting shoots.
Keywords:
canopy structure, central leader, centrifugal training, Malus domestica, reiteration, shoot type, spatial pattern, tree ideotype.
