Abstract

Witch weed (Striga gesnerioides) is a root parasitic weed of tobacco and cowpea in Sub- Saharan Africa. It is very difficult to control and host plant resistance is the most promising effective method affordable to small-scale farmers. This study was done to screen local tobacco genotypes for tolerance and resistance to Striga gesnerioides infection. Laboratory screening experiments were conducted during the 2016/17 season using fifteen local tobacco genotypes. The experiments were done using an Agar gel technique at the University of Zimbabwe, with treatments replicated four times in a Randomised Complete Block Design (RCBD). All tobacco genotypes significantly (p<0.05) stimulated the germination percentage and there were significant differences (p<0.05) in the germination distance of Striga seeds. The tobacco genotypes K RK66 and T74 had the closest Striga germination distance and the lowest germination percentages of Striga seeds, indicating their ability to produce low germination stimulants (strigolactones). This study revealed that all the tobacco genotypes were susceptible to Striga infection except the genotypes K RK66 and T74 which showed some level of tolerance and could be adopted by farmers in Striga infested areas. Additional evaluations, targeting the parental lines of the tolerant cultivars and is recommended as further studies.

Keywords: Striga gesnerioides; Tobacco; Strigolactones