Striga hermonthica SEED GERMINATION THROUGH ROOT EXUDATES OF INDIGENOUS SUB-SAHARAN WEED SPECIES

This study was conducted to evaluate root exudates from sub-Saharan indigenous weed species to induce germination of Striga hermonthica (Del.) Beth., a root parasitic weed. Significant variation in Striga seed germination was observed, ranging from an absence to the induction of 74.1% Striga seeds. Direct compa-rison of Striga germination was obscured by differences in weed root biomass as within most of the species, a direct proportional relation between Striga seed germination and weed root dry weight was observed. Expression of Striga seed germination in % g-1 root dry weight (GIC) was found a suitable solution as stable values for GIC were obtained despite considerable variation in root dry weight. GIC was significant for 25 species and highest with Commelina forskalaei and Sesamum alatum (9.91; 9.78 % g-1 dry root, respectively). Striga seeds did not germinate following application of exudates from Mitracarpus scaber and Phyllanthus pentrandus. These results show that a substantial number of indigenous weed species may serve as alternative trap crops to control the parasites seed bank. Furthermore, the timing of weeds in the cropping system may provide a (partial) explanation for the erratic infestation levels found across fields and years that have dazed researchers for many years.