BIOLOGICAL CONTROL OF STRIGA HERMONTHICA WITH FUSARIUM SOLANI
AI IDRIS1, NE AHMED2 and AGT BABIKER2
1Rahad Agric. Scheme, Khartoum, Sudan; 2Agricultural Research Corporation , Medani, Sudan
Background and objectives
Results and discussion
The results clearly indicated that extracellular metabolites secreted by F. solani woud be at least partly responsible for the observed inhibition of Striga germination. The inhibitory effect of F. solani to Striga seeds was not affected by the stimulants ACC (200 p.p.m.), OR24 (1 p.p.m.) and ethephon (1 p.p.m.). OR24 alone and ACC or ethephon did not trigger Striga seed germination in presence of F. solani filtrate. Addition of the fungus at 0, 2 and 4 h after OR24 application greatly inhibited Striga seed germination (3%). However, delay of application between 6 and 12 h after addition of stimulant increased germination to 33-88%. Failure of F. solani filtrate, when applied 6 h after GR24 to inhibit germination, indicated that germination had already started.
The inability of ACC and GR24 to stimulate Striga seed germination in presence of F. solani filtrate suggests that the filtrate inhibits either ethylene biosynthesis or ethylene action . Ability of the filtrate to inhibit germination in the presence of ethephon suggests that the fungus filtrate is not an ethylene biosynthesis inhibitor, but more likely it inhibits ethylene action. However, an effect of fungal filtrate may be due to alteration on seed structure leading to changes in structure of the stimulant or ethylene binding sites . The fungus satisfied most requirements of a successful biocontrol agent, and inhibition of Striga seeds before germination will save the crop completely from Striga damage.