Holoparasitic plants such as Orobanche are thought to act as a strong sink for host resources. Here, we tested the effect of nutrient supply to parasitized or unparasitized roots of red clover plants growing in a splot root box. We found that host growth was strongly suppressed by the parasite when nutrients were fed to parasitized, but not unparasitized, roots. Our data suggests that the sink steength of Orobanche is variable and contingent on local nutrient availability.
