title: Exploring bud dormancy completion with a combined architectural and phenological analysis: the case of apple trees in contrasting winter temperature conditions.
abstract: OBJECTIVE
  The branching pattern and phenology of trees result from interactions between the tree's genetic constitution and environmental conditions. Temperature strongly affects the duration of bud dormancy and further shoot growth. Our hypothesis was that shoot architecture is strongly affected by winter temperatures determining both the position and budburst of vegetative laterals with a lower effect on their outgrowth.
  
  
  METHODS
  The study was conducted on four apple cultivars characterized by various chilling requirements and grown in two contrasting winter temperature conditions. A two-step approach was designed to quantify at the shoot scale first the branching pattern and second two phenological stages of vegetative laterals, budburst and outgrowth. A categorical variable, the branching zone, was built to summarize the lateral position along the shoot. It was integrated into the phenological analysis as a factor together with the cultivar and the winter temperature.
  
  
  RESULTS
  Temperature had a main effect on the distribution of vegetative laterals along the shoot. It also strongly affected budburst, which was also affected by the cultivar and the branching zone. The outgrowth of the lateral was not significantly affected by temperature but was significantly affected by the cultivar and the branching zone. Furthermore, the delayed senescence and subsequent leaf persistence during winter, characterizing the apple tree in the mild winter temperature condition, had only a weak effect on the distribution of vegetative laterals and on budburst and lateral outgrowth.
  
  
  CONCLUSIONS
  The actual shoot architecture and budburst result from an ordered sequence of events with a pivotal role of winter temperatures on the dormancy completion of individual lateral buds. Endogenous factors related to the cultivar branching pattern overtake the temperature effect on the lateral outgrowth.
authors.affiliation: INRA, UMR AGAP, 34398 Montpellier, France.
authors.forename: Juliano Dutra
authors.initials: JD
authors.lastname: Schmitz
authors.forename: Yann
authors.initials: Y
authors.lastname: Guédon
authors.forename: Flavio Gilberto
authors.initials: FG
authors.lastname: Herter
authors.forename: Gabriel Berenhauser
authors.initials: GB
authors.lastname: Leite
authors.forename: Pierre-Éric
authors.initials: PÉ
authors.lastname: Lauri
mesh_terms: D016000:Cluster Analysis; D003080:Cold Temperature; D035264:Flowers / Q000033:anatomy & histology / Q000502:physiology; D027845:Malus / Q000033:anatomy & histology / Q000502:physiology*; D008390:Markov Chains; D010641:Phenotype; D057445:Plant Dormancy; D018515:Plant Leaves / Q000033:anatomy & histology / Q000502:physiology; D018520:Plant Shoots / Q000033:anatomy & histology / Q000502:physiology; D012621:Seasons; D013997:Time Factors; D014197:Trees
keywords: Malus domestica; branching dynamics; budburst; dormancy; hidden semi-Markov chain; multiple change-point model; phenology; vegetative proleptic lateral; winter temperature