In vitro Studies of Imazethapyr and GR24 Effects on Early Developmental Stages of Striga hermonthica (Del.) Benth.

Aims: A series of laboratory experiments were conducted to investigate the effects of Imazethapyr on Striga germination and haustorium initiation in response to different chemical stimulants.

Study Design: A completely randomized design with five replicates.

Place and Duration of Study: A series of laboratory experiments was undertaken at the College of Agricultural Studies, Sudan University of Science and Technology (SUST) at Shambat, during the season 2012/2013.

Methodology: Striga seeds were sprinkled on (GFFPD), in Petri-dishes. Aliquots (5ml) of the herbicide at 10, 20, 40, 60, and 80 µM were added to each petri-dish. The Petri-dishes, were sealed with Parafilm, wrapped in aluminum foil and incubated in the dark at 30°C±2 for 14 days. A control with water was included. The seeds were subsequently treated with 20µl (aliquots) of GR24 at 0.01 and 0.1 ppm per disc. A piece of filter paper, moistened with sterilized distilled water, was placed in the centre of each petri-dish to maintain moist condition. The Petri-dishes were sealed with parafilm, wrapped in aluminum foil and incubated in the dark at 30°C±2 for 24 h.

Results: Seeds conditioned in Imazethapyr at 10-80 µM displayed inconsistent germination in response to GR24 and the germination was poorly correlated with herbicide concentration (r= -0.2). Seeds conditioned in imazethapyr at 60-80 µM for 10 or 15 days prior to treatment withGR24 at 0.01 ppm.reducedStriga germination comparable to the respective control. Striga germilings resulting from seeds conditioned in imazethapyr at 40 µM exhibited significant reductions (36%) in haustorium initiation in response to DMBQ as compared to the control.

Conclusion: Imazethapyr, irrespective of concentration reduced Striga germination, radicle length and haustorium initiation significantly.