Efficiency Gained By Screening Segregating Soybean Progenies With Soybean Cyst Nematode Race 2 Versus Race 5

Soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) is a major pest of soybean [Glycine max (L.) Merr.] in the USA and has many races. The use of SCN resistant cultivars effects changes in the ability of H. glycines field populations to parasitize these cultivars. The objective of this experiment was to determine if screening for race 2 resistance alone was sufficient to identify resistance for both races 2 and 5. Progenies of crosses involving 'Hartwig" soybean were tested for resistance to either SCN race 2 or 5 in the F-2 generation and for resistance to both races in the F-2:3 generation in greenhouse studies. Individual plants were grown in soil infested with 1000 eggs of the appropriate race. Resistant plants were transplanted to the field for seed production. Progenies from the harvested plants were tested with both races in separate tests. All F-2:3 progenies resistant to race 2 were also resistant to race 5. Only 64% of F-2:3 progenies resistant to race 5 were also resistant to race 3. These results indicate that it is more efficient to screen for race 2 resistance alone than to screen for resistance to either race 5 or both races when resistance to both races is sought from crosses involving Hartwig.