Density-Dependent Yield of Heterodera glycines-Resistant and -Susceptible Cultivars.

Yield of the soybean (Glycine max) cultivar Hartwig with resistance to all races of Heterodera glycines was compared to that of the susceptible cultivar, Deltapine 105, in a field infested with race 2 of this pathogen. The field had previously been in a cropping sequence experiment that provided a range of H. glycines population densities affording the opportunity to evaluate yield potential of resistant and susceptible cultivars in the presence of different levels of soybean cyst nematode in 1992. Plots were planted again in 1993 with the two cultivars in sequences that included Hartwig following Hartwig or Deltapine 105, and Deltapine 105 following Hartwig or Deltapine 105. The yield of Hartwig was inferior to Deltapine 105 at low population densities of H. glycines, but Hartwig yielded more than Deltapine 105 at high population densities. Hartwig was effective in suppressing H. glycines population density compared to susceptible Deltapine 105. The seed yield of Hartwig following Deltapine 105 or Hartwig, and Deltapine 105 following Hartwig yielded more than Deltapine 105 grown for 2 years.