Experiments were conducted in four commercial fields differing in severity of iron-deficiency chlorosis (IDC), and soybean cyst nematode (SCN) in Waseca and Lamberton, Minnesota to determine the interaction between the IDC and SCN. Each experiment was a randomized complete block with a factorial treatment design including 23 cultivars with or without traits of resistance to SCN, and IDC. The study illustrated the interactive effects of the two defensive traits on the diseases and soybean yields. IDC rating was higher in SCN-susceptible than SCN-resistant soybean, suggesting SCN infection increased IDC. Resistance to IDC apparently increased SCN reproduction due to better soybean plant growth. Yield response to the defensive traits depended on the disease pressures in a field. When both IDC and SCN were present in a field, deploying SCN-resistance was the best solution to the problems. However, SCN-resistance suppressed soybean yields when used in fields without the disease problems. IDC-resistance increased yield of SCN-susceptible cultivars, but it did not result in detectable yield benefit of SCN-resistant cultivars in SCN-infested sites. Effective use of the defensive traits for management of IDC and SCN requires specific knowledge of the disease problems present in a field.
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Acknowledgments The authors thank J. Ballman, W. Gottschalk, C. Johnson, S. Quiring, and R. Solyntjes for the technical assistance. We also thank S. Weisberg for the statistical assistance and L. Scott and G. Sciumbato for the critical review of an earlier version of the manuscript. The research was supported by the Minnesota Soybean Producers check-off funding through the Minnesota Soybean Research and Promotion Council and the Minnesota Agricultural Experiment Station.
- Defensive trait
- Heterodera glycines
- Iron-deficiency chlorosis
- Soybean cyst nematode