Abstract:

Species of broomrape (Orobanche spp. and Phelipanche spp.) are among the most damaging parasitic weed species worldwide. These species reproduce through abundant seed production. Their seeds are protected by complex dormancy mechanisms, in particular a need for host-specific chemical germination cues. Broomrape seeds have been shown to remain viable in the soil for many years. While the depletion of the soil seed bank, e.g. using trap crops that induce suicide germination of broomrape seeds, could potentially be a way to control these weeds, the practical uptake of this approach has remained very limited. To explore the potential of an array of cereal species to serve as trap crop, laboratory experiments were conducted to qualitatively check for the existence of cereal-broomrape interactions and to quantify possible effects on Orobanche/Phelipanche seed banks. For this purpose, seeds of the following cereals were used: wheat, rye, barley, oats, maize, rice, sorghum and pearl millet. Several accessions of O. crenata, O. cumana and P. ramosa were used as parasite species. As host species, pea, sunflower and tomato were grown. Cereal and parasite species were crosswise-combined to assess interactions. Maize was found to be most effective in stimulating the germination of the broomrapes. Among the parasite species, P. ramosa proved most ready to germinate in the presence of cereal root exudates. The interaction was observed in various combinations of maize cultivars and P. ramosa accessions. As a result, strong evidence of germination induction in P. ramosa seeds by maize was collected.

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