Genetic Variability For Resistance to Striga asiatica in Maize

Summary A field experiment was conducted at the USDA Witchweed Field Station in Dillon, S.C., USA, to evaluate genetic variability for resistance to Striga asiatica in a diverse group of maize genotypes. Genotypes differed significantly in the number of S. asiatica they supported. The most resistant genotypes, Pioneer Hybrid 3181, a commercial USA hybrid adapted to the southern USA, and TZI-30, an inbred adapted to the lowland tropics, supported less than 15% of the S. asiatica of the susceptible check, Pioneer Hybrid 3147. Early counts and dry weight of S. asiatica were significantly correlated with counts at the end of the season (r=0.58 and r=0.84, n=30, respectively). Average yield of the resistant adapted hybrid P.H. 3181 was 2.71 t/ha while the yield of the adapted susceptible check P.H. 3147 was only 0.89 t/ha. Using multiple checks, and converting measured plot values to a percent of the nearest check did not reduce the c.v. of the experiment, nor significantly alter the ranking of the genotypes.