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Impact of Genetic Resistance on Soybean Cyst Nematode

Soybean Performance at SCN-Infected Locations, 1999-2000

            Tim Todd
            Plant Pathology Department
            Kansas State University
            785-532-1350
            email: nema@plantpath.ksu.edu

  The performance of public and private SCN-resistant and susceptible cultivars have   been evaluated in three environments during the past three years: Northeast, Southeast,   and South Central KS. In Cherokee Co., under relatively high nematode pressure,   resistant cultivars have consistently out-yielded susceptible cultivars by ~30% (Figure   1a). In environments with moderate nematode pressure, the performance of resistant   cultivars is still enhanced by 10-15% (Figure 1b).

Effect of Resistance Source and SCN Population on   Performance and Durability of Resistance Cultivars

The relative performance of soybean cultivars derived from the SCN resistance sources   Peking (Delsoy 4500), PI 88788 (Delsoy 4210), and PI 437654 (Hartwig) were   compared for three SCN populations over nine years. Nematode reproduction on Delsoy   4210 increased over time, resulting in a corresponding decrease in performance of that   cultivar at two of the three locations (Figures 2a and 2c). Selection pressure has not   resulted in increased reproduction or reduced yield for Delsoy 4500 or Hartwig after nine   years. Rotations of resistance sources have not had a consistent effect on nematode   reproduction or soybean yield.
 

Soybean cyst with eggs                                               J2 Juvenile            

           Cyst nematode infected field                    Cyst close-up with Rhizobium nodule

                Root System with soybean                      Screening Soybean for resistance to Soyb

cyst females attached                                                    cyst nematode