Insights into secondary growth in perennial plants: its unequal spatial and temporal dynamics in the apple (Malus domestica) is driven by architectural position and fruit load |
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Authors: | P ?? Lauri J J Kelner C Trottier and E Costes |
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Institution: | 1UMR DAP, INRA-SUPAGRO-CIRAD-UM II. Equipe ‘Architecture et Fonctionnement des Espèces Fruitières’, CIRAD Lavalette, Avenue Agropolis, TA A-96/03, 34398 Montpellier Cedex 5, France;2Université Montpellier II, UMR I3M, #5149, Equipe ‘Probabilités et Statistique’, 34095 Montpellier Cedex 5, France |
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Abstract: | Background and AimsSecondary growth is a main physiological sink. However, the hierarchy between the processes which compete with secondary growth is still a matter of debate, especially on fruit trees where fruit weight dramatically increases with time. It was hypothesized that tree architecture, here mediated by branch age, is likely to have a major effect on the dynamics of secondary growth within a growing season.MethodsThree variables were monitored on 6-year-old ‘Golden Delicious’ apple trees from flowering time to harvest: primary shoot growth, fruit volume, and cross-section area of branch portions of consecutive ages. Analyses were done through an ANOVA-type analysis in a linear mixed model framework.Key ResultsSecondary growth exhibited three consecutive phases characterized by unequal relative area increment over the season. The age of the branch had the strongest effect, with the highest and lowest relative area increment for the current-year shoots and the trunk, respectively. The growth phase had a lower effect, with a shift of secondary growth through the season from leafy shoots towards older branch portions. Eventually, fruit load had an effect on secondary growth mainly after primary growth had ceased.ConclusionsThe results support the idea that relationships between production of photosynthates and allocation depend on both primary growth and branch architectural position. Fruit load mainly interacted with secondary growth later in the season, especially on old branch portions. |
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Keywords: | Branch age fruit load growth phase Malus domestica (apple) primary growth secondary growth tree architecture |
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