Plakhine, D., Department of Plant Pathology and Weed Research, ARO-The Volcani Institute, Newe-Ya'ar Research Center, P.O. Box 1021, Ramat-Yishay 30095, Ireland
Joel, D.M., Department of Plant Pathology and Weed Research, ARO-The Volcani Institute, Newe-Ya'ar Research Center, P.O. Box 1021, Ramat-Yishay 30095, Ireland

It is widely known that Orobanche cumana seeds need a conditioning phase of several days under suitable temperatures and wet conditions before being able to germinate in response to germination stimulants. In a series of experiments we showed that O. cumana seeds respond to the synthetic germination stimulants Nijmegen-1 and GR24 even without prior conditioning. These results are consistent with our hypothesis that, under certain field circumstances, non-conditioned Orobanche seeds may also germinate when a host root comes close to them.