Abstract In Wallonia (Belgium) almost half of the arable land undergoes a four-year crop rotation. Winter crops often follow spring crops within the rotation scheme. This is a challenging context to implement silvoarable agroforestry (AF) systems, in terms of species choice, plot design, and tree management, since the periods of crop resource capture clearly differ. AF is defined here as the deliberate introduction of trees in the cropped area. Combining spring crops with trees induces an important overlap of the growing period of both plants which has an impact on one of the primary resources for both plants: light. In this study, we monitored an important spring crop for the region, sugar beet (Beta vulgaris L.). We quantified the impact of the shade environment on sugar beet morphology, growth dynamic, productivity and quality. We used artificial shade to isolate the impact of shade from other possible interactions in agroforestry systems. The field experiment was conducted over two consecutive years (2015 and 2016) on the experimental farm of Gembloux Agro-Bio Tech, Belgium. We installed the shade structures so as to reproduce a North-South and East-West tree line orientation. The experiment simulated canopy shade of late-flushing hybrid walnut by overlapping military camouflage netting. In 2015, the North-South orientation induced two distinct shade conditions: periodic shade (PS) and continuous shade (CS). In 2016, the East-West orientation created two periodic shade treatments, one during the morning (PSam) and one in the afternoon (PSpm). In both experimental years, shading was imposed from mid-June until harvest, resulting in 132 days of shade in 2015, and 140 days in 2016 on a growing season of 192 (2015) and 188 (2016) days in total. Sugar beet under shade tended to produce longer petioles. In 2015, at the first sampling date, we observed a higher specific leaf area and single leaf area under the CS and PS treatment, while there were no differences in 2016. All the shade treatments significantly changed the dry matter partitioning between the sugar beets compartments. Under the shade treatments, the quantity of biomass allocated to the leaves was significantly reduced as compared to the proportion of biomass for the petioles. Likewise, quantity of root dry matter formed per gram of shoot dry matter was reduced under shade. Thus, at harvest, all the shade treatments significantly reduced the final root dry matter and sugar yield. Furthermore, sugar beet quality, and more specifically sugar extractability, was affected by shading but to a lesser extent than for the final root dry matter and sugar yield.

中文翻译：

---

温带动态遮荫环境下甜菜发育

摘要 在瓦隆（比利时），近一半的耕地经历了四年轮作。冬季作物通常在轮作计划中紧随春季作物之后。在物种选择、地块设计和树木管理方面，这是实施可林农林业 (AF) 系统的一个具有挑战性的背景，因为作物资源捕获的时期明显不同。AF 在此被定义为在种植区有意引入树木。将春季作物与树木相结合会导致两种植物的生长期出现重要重叠，这会对两种植物的主要资源之一：光产生影响。在这项研究中，我们监测了该地区一种重要的春季作物，甜菜 (Beta vulgaris L.)。我们量化了遮荫环境对甜菜形态、生长动态、生产力和质量的影响。我们使用人工遮荫将遮荫的影响与农林业系统中其他可能的相互作用隔离开来。田间试验连续两年（2015 年和 2016 年）在比利时 Gembloux Agro-Bio Tech 的试验农场进行。我们安装了遮阳结构以再现南北和东西树线方向。实验采用重叠军用迷彩网模拟晚冲杂交胡桃树冠树荫。2015 年，南北朝向导致了两种不同的遮荫条件：周期性遮荫 (PS) 和连续遮荫 (CS)。2016 年，东西方向创造了两种定期遮阳处理，一种在早上 (PSam)，一种在下午 (PSpm)。在这两个实验年中，从 6 月中旬到收获期间都进行了遮荫，导致 2015 年有 132 天的遮荫天数，2016 年为 140 天，生长期共 192（2015）天和 188（2016）天。遮荫下的甜菜往往会产生更长的叶柄。2015 年，在第一个采样日期，我们观察到 CS 和 PS 处理下的比叶面积和单叶面积更高，而 2016 年没有差异。所有遮荫处理都显着改变了甜菜隔室之间的干物质分配. 在遮荫处理下，与叶柄的生物量比例相比，分配给叶片的生物量显着减少。同样，在遮荫下，每克地上部干物质形成的根干物质数量减少。因此，在收获时，所有遮荫处理都显着降低了最终根干物质和糖产量。此外，甜菜质量，