Haustorial initiation percentage was calculated at 5 d by dividing the number of germinated striga seed having recognizable haustoria by the number of germinated weed seeds within the 3-mm sorghum root zone.
Accessions were classified for their haustorial initiation capacity on the basis of their MHD values.
The most distinguishing attribute found in this collection of wild sorghums is the apparent low haustorial initiating activity of some accessions.
3, the percentage of germinated striga with haustoria along the sorghum root was taken as an additional measure of haustorial initiation activity.
Host-derived cues of haustorial initiation are different from compounds that stimulate striga seed germination.
The survey of the wild sorghum collection revealed accessions with a wide range of MHD values (Table 1), such as IS18874 and HD#758 with mean MHD > 4 mm and the low haustorial initiators PQ-434, IS14301, IS14313 and IS18803 with mean MHD < 0.
Low MHD sorghums on the other hand may have all the traits needed for the coordinated release of xenognostic quinones to stimulate haustorial formation in surrounding striga, but their roots may exude compounds like auxins, which are powerful inhibitors of haustorial induction (Keyes et al.