Agroforestry is promoted as a way to improve the sustainability of horticultural systems through plant diversification and also to mitigate climate change through carbon sequestration. It could also alleviate excessive light and temperature in high-radiation regions of the world. However, little is known about the long-term shade adaptation of the temperate fruit tree in agroforestry systems. A study was developed to investigate apple growing under walnut trees in two shade conditions compared to a full light condition. Our aim was to quantify the plasticity of traits and the covariations between traits in these three light conditions using a multiscale approach considering different scales from whole tree to annual shoot and inflorescence. Shade did not affect the height of the apple trees, while it reduced the diameter of the trunk and branches. On the other hand, the total number of growing shoots was reduced in shade, and flowering and fruiting were fewer and more irregular than in full light. Strikingly, at the whole tree scale, covariations between vegetative traits (trunk cross-sectional area versus mean branch cross-sectional area) and between vegetative and reproductive traits (trunk cross-sectional area versus total number of inflorescences) were not altered by shade. However, at the shoot scale, return-bloom was significantly reduced by shade, whereas at the inflorescence scale shade did not affect leaf number or leaf area. We propose a shade adaptation syndrome that includes not only shade intensity but also shade dynamics during the growing season and over consecutive years.

中文翻译：

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农林业中的苹果树——研究营养和繁殖性状的可塑性


农林业被认为是通过植物多样化提高园艺系统可持续性以及通过固碳减缓气候变化的一种方式。它还可以缓解世界高辐射地区的过度光照和温度。然而，人们对农林复合系统中温带果树的长期遮荫适应知之甚少。一项研究旨在调查核桃树下苹果在两种遮荫条件和全光照条件下的生长情况。我们的目的是使用多尺度方法来量化这三种光照条件下性状的可塑性和性状之间的协变，考虑从整棵树到一年生芽和花序的不同尺度。遮荫不影响苹果树的高度，但减少了树干和树枝的直径。另一方面，与全光照相比，在遮荫下生长的芽总数减少，开花和结果更少且更不规则。引人注目的是，在整个树木尺度上，营养性状（树干横截面积与平均枝条横截面积）之间以及营养性状和繁殖性状（树干横截面积与花序总数）之间的协变并未因遮荫而改变。然而，在枝条尺度上，遮荫显着减少了返花，而在花序尺度上，遮荫并不影响叶数或叶面积。我们提出了一种遮荫适应综合症，不仅包括遮荫强度，还包括生长季节和连续年份的遮荫动态。