Germination, Host Preference, and Phenolic Content of Witchweed (Striga hermonthica) Seed Populations

Phenolic content, germination percentage, and host preference were compared among 11 seed populations of witchweed (Striga hermonthica (Del.) Benth. # STRHE). Significant differences in germination percentage occurred among the seed populations after preconditioning by their exposure to different durations of warm-moist conditions. Greatest percentage of seed germinated after 8 days of preconditioning. Preconditioning for more than 16 days reduced percentage germination. The host specificity range of witchweed seed populations that parasitized pearl millet [Pennisetum americanum (L.) K. Schum] was broader than were those seed populations that attacked sorghum [Sorghum bicolor (L.) Moench.]. Results of thin-layer chromatography indicated large variations in phenolic content among the witchweed seed populations.