Shade avoidance alters the way plants grow, usually causing them to grow taller at the expense of placing resources into leaves, roots, seeds, and other harvestable materials. Sugar beet (Beta vulgaris L.) is a rosette-forming biennial species that has limited capacity to grow tall in the first year of growth. In the context of crop–weed competition, it is mostly unknown to what extent shade avoidance reduces yield in sugar beet relative to other effects like resource competition. To determine the extent of yield loss due to shade avoidance in a field-relevant situation, sugar beets were grown alongside Kentucky bluegrass (Poa pratensis L.) sod in a field study. Roots were separated with a steel root barrier placed into the ground between the grass and beets. Four treatments included a weed-free control (no root barrier or grass), a root barrier control (with root barrier but no grass), shade avoidance (with root barrier and grass), and full competition (with grass but no root barrier). The presence versus absence of grass was the primary driver of effects on measured sugar beet growth and yield parameters, regardless of whether a root barrier was present. Leaf number and root length were also impacted by the presence of the root barrier. These results suggest that shade avoidance is at least as important as root interactions and resource depletion in the context of early-season sugar beet yield loss due to weeds.

避荫会改变植物的生长方式，通常会导致它们长得更高，但代价是牺牲叶子、根、种子和其他可收获材料的资源。甜菜（Beta vulgaris L.）是一种形成莲座丛的二年生物种，在生长的第一年长高的能力有限。在作物与杂草竞争的背景下，相对于资源竞争等其他影响，目前尚不清楚避荫会在多大程度上降低甜菜的产量。为了确定在田间相关情况下由于避荫而造成的产量损失程度，在田间研究中将甜菜与早熟禾 ( Poa pratensis L.) 草皮一起种植。用放置在草和甜菜之间的地下的钢根屏障将根分开。四种处理包括无杂草控制（无根屏障或草）、根屏障控制（有根屏障但无草）、避荫（有根屏障和草）和完全竞争（有草但无根屏障） 。无论是否存在根屏障，草的存在与否是影响甜菜生长和产量参数的主要驱动因素。叶数和根长也受到根屏障存在的影响。这些结果表明，在杂草导致早季甜菜产量损失的情况下，避免遮荫至少与根部相互作用和资源枯竭一样重要。