Plants can respond to competition with a myriad of physiological or morphological changes. Competition has also been shown to affect the foraging decisions of plants belowground. However, a completely unexplored idea is that competition might also affect plants’ foraging for specific elements required to inhibit the growth of their competitors. In this study, we examined the effect of simulated competition on root foraging and accumulation of heavy metals in the metal hyperaccumulating perennial plant Arabidopsis halleri, whose metal accumulation has been shown to provide allelopathic ability. A. halleri plants originating from both metalliferous and non-metalliferous soils were grown in a “split-root” setup with one root in a high-metal pot and the other in a low-metal one. The plants were then assigned to either simulated light competition or no-competition (control) treatments, using vertical green or clear plastic filters, respectively. While simulated light competition did not induce greater root allocation into the high-metal pots, it did result in enhanced metal accumulation by A. halleri, particularly in the less metal-tolerant plants, originating from non-metalliferous soils. Interestingly, this accumulation response was particularly enhanced for zinc rather than cadmium. These results provide support to the idea that the accumulation of metals by hyperaccumulating plants can be facultative and change according to their demand following competition.

植物可以通过无数生理或形态变化来应对竞争。竞争也被证明会影响地下植物的觅食决定。然而，一个完全未开发的想法是，竞争也可能影响植物对抑制竞争对手生长所需的特定元素的觅食。在这项研究中，我们研究了模拟竞争对金属超积累多年生植物拟南芥中重金属的根觅食和积累的影响，其金属积累已被证明具有化感作用。A.halleri来自含金属和非含金属土壤的植物在“分根”设置中生长，一根根在高金属盆中，另一根在低金属盆中。然后分别使用垂直绿色或透明塑料过滤器将植物分配到模拟光竞争或无竞争（对照）处理。虽然模拟的光照竞争并没有导致更多的根分配到高金属盆中，但它确实导致了A.halleri 的金属积累增加，尤其是来自非金属土壤的耐金属性较差的植物。有趣的是，对于锌而不是镉，这种积累反应特别增强。这些结果支持这样一种观点，即超积累植物对金属的积累可以是兼性的，并根据竞争后的需求而变化。