Screening finger millet (Eleusine coracana L. Gaertn) genotypes for resistance to witch weed (Striga asiatica L. Kuntze) infection under controlled environments

Witch weed (Striga asiatica L. Kuntze) is an obligate hemi-parasitic weed that causes severe yield losses in cereals. The use of tolerant or resistant genotypes is perceived to be the most economically feasible and effective method of control. Hence this project aimed to determine the response of finger millet genotypes to S. asiatica infection. Three genotypes that were bred at the International Crop Research Institute of Semi-arid tropics (ICRISAT) were evaluated with Striga and without Striga infestation under glasshouse conditions at the University of Zimbabwe during the 2017/2018 growing season. The greenhouse study was laid out as a 3 x 2 factorial in a Randomised Complete Block Design (RCBD) with finger millet genotype and Striga infestation level as factors. In the laboratory assay, the three finger millet genotypes were screened for pre-attachment resistance using the Ager-gel technique arranged in a Complete Randomized Design (CRD) with ten replications. The finger millet genotype SDFM1702 had significantly (p<0.05) lower Striga germination percentage and shorter Striga germination distance from the finger millet root than the other genotypes. In the glasshouse experiment there was a significant (p<0.05) genotype x Striga interaction on stem biomass, root biomass, total above ground biomass and grain yield where SDFM1702 showed tolerance. However, Striga infection did not significantly (p>0.05) reduce the final plant height of the genotype SDFM1702. There was a significant (p<0.05) difference on Striga count where SDFM1702 recorded the least emerged S. asiatica weeds. Striga asiatica infection significantly (p<0.05) reduced grain yield of all genotypes. The finger millet genotypes screened showed different levels of tolerance to Striga infection, where genotype SDFM1702 appeared to be tolerant. Therefore, this high yielding genotype and Striga have the potential to be widely adopted as they are adaptable and suitable to the dry and Striga endemic areas.