Performance of Blends of Soybean Cyst Nematode Resistant and Susceptible Cultivars

Abstract

Use of soybean cyst nematode (SCN), (Heterodera glycines Ichinohe), resistant cultivars of soybean (Glycine max (L.) Merr.) is common practice to control losses due to this pest. The experiment was conducted to compare blends of resistant and susceptible cultivarswith their yield response when grown in pure monoculture stands. Two SCN-resistant cultivars Bedford and Bradley, three susceptible cultivars or breeding lines, Essex, York, and N79-491, and blends of resistant and susceptible cultivars (50:50 ratio) were tested against soybean monoculture in a SCN Race 14-infested field. The mean yield (over 5 yr) of Bedford, Bradley, Essex, York, and N79-491 grown in monoculture was 1707, 1703, 903,1063, and 1379 kg ha−1, respectively. Yield of blends were generally similar to their resistant cultivar components in monoculture but they were always greater (P = 0.05) than the susceptible cultivar components. The Bedford and Essex blend resulted in the greatest yield, which was 672 kg ha−1 (51%) greater than the mean of component crop yields in pure stand. The race designation of the SCN population changed from Race 14 to Race 5 when resistant Bedford and Bradley were grown, from Race 14 to 9 when susceptible cultivars were grown, and from Race 14 to 2 in plots containing blends of resistant and susceptible cultivars or lines. Resistant cultivars grown with susceptible cultivars or lines in blends had lower numbers of cysts on the roots 30 d after planting than resistant cultivars grown in pure stands. Blends of resistant and susceptible cultivars can maintain soybean yields at acceptable levels by minimizing the selection pressure on the nematode population for their ability to parasitize resistant cultivars