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ARCHITECTURE AND FRUITING OF APPLE TREE IN AGROFORESTRY – LINKING ARCHITECTURAL DEVELOPMENT, FLOWERING AND XYLEM FLOW

Authors
  • Pitchers, Benjamin
Publication Date
Apr 02, 2021
Source
HAL
Keywords
Language
English
License
Unknown
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Abstract

Agroforestry systems structured around fruit trees to produce fresh fruit is still under-developed in temperate zones. This study is based on the idea that the fruit tree can be integrated into multi-strata agroforestry systems where it would be grown with timber trees occupying the upper stratum and shrubs and/or herbaceous plants in the lower stratum. In addition to the production of fresh fruit, such systems would then combine different agro-ecosystemic services. The study focuses on a major temperate fruit species at the national and global levels, the apple tree. The general objective is to acquire a detailed knowledge of the tree's architectural development, its flowering and the quality of its fruiting, along these competition gradients. The work focuses on three actions: (i) defining an indicator to characterize each apple tree environment in this complex agrosystem, (ii) analyse at the tree scale the impact of agroforestry on morphological, phenological and architectural traits, and (iii) analysing the daily and annual sap flow regarding environmental variables and in relation to the aforementioned architectural traits. Using the light as a variable to analyse our architectural data, we have shown that apple trees did express shade avoidance traits affecting morphology (decreased taper and increased slenderness and specific leaf area), architecture (fewer growing shoots and proportion of flower clusters) and phenology (reduced number of days at full bloom). Finally, we have shown that sap flow and transpiration per unit of leaf area was affected by environmental variables (vapour pressure deficit and reference evapotranspiration). Shade did not change apple trees sap flow daily dynamics and reduced water and transpiration per unit of leaf area mainly because of morphological and architectural adaptation to shade in our experimental conditions. An increase of leaf area or a complexification of the apple tree architecture (i.e. the number of ramifications) increased transpiration per unit of leaf area during the summer. Our results suggest that while the architecture of apple trees is modified by a reduction in light intensity, it is not until a reduction of 65% that the capability to produce fruit is impeded.

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