Effect of Striga gesnerioides on Cowpea (Vigna unguiculata L.Walp) Yield Components

Abstract Background: The parasitic plant Striga gesnerioides (Willd) Vatke is becoming a threat to cowpea production in the three northern regions of Ghana (Derived Savanna, Southern Guinea Savanna and Northern Guinea Savanna. The objective of this study was to determine the extent of yield loss due to Striga in F3 progenies and their parental lines. A total of twelve cowpea genotypes were evaluated to ascertain the level of damage by S. gesnerioides. Results: The results indicated varietal differences with respect to Striga susceptibility in the genotypes studied. The susceptible varieties (Asomdwee and Hewale) showed an array of emerged Striga shoots. The F3 progenies (s52, s37, s147, s272) also exhibited the same trend. The resistance genotypes (IT99K-573-1-1 and GH3684), however, were totally devoid of Striga shoots. Similarly, some of the F3 progenies (r246, r286, r282 and r69) were completely without Striga shoot. Striga height was higher on susceptible genotypes than those that are moderately resistance. The results obtained from this study revealed a percentage reduction in pods per plant range between 45.12 and 49.53 %; grain yield reduction ranged between 78.22 and 87.17% on susceptible genotypes which indicated that Striga had greater influence on yield. Fodder yield was also significantly reduced between 70.59 and 73.03% in susceptible genotypes. There was a strong negative correlation (r = -0.724) between grain yield and days to Striga emergence. A significant negative correlation (r = -0.762) was also found between Striga shoot per plant and grain yield. Conclusion: Striga infestation reduced pods per plant to 49%, grain yield loss to 87% and fodder yield loss to 73%. This study has revealed potential F3 genotypes resistant to S. gesnerioides under pot experiment. The implication is that if susceptible genotypes are grown the farmer stand the chance of loosen everything to the parasite.