|Chen, Senyu - UNIVERSITY OF MINNESOTA|
|Kurle, James - UNIVERSITY OF MINNESOTA|
|Miller, Daniel - UNIVERSITY OF MINNESOTA|
|Nelson, George - UNIVERSITY OF MINNESOTA|
|Klossner, Lee - UNIVERSITY OF MINNESOTA|
|Hansen, Neil - COLORADO STATE UNIVERSITY|
Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 26, 2007
Publication Date: September 5, 2007
Citation: Chen, S., Kurle, J.E., Stetina, S.R., Miller, D.R., Nelson, G.A., Klossner, L.D., Hansen, N.C. 2007. Interactions between iron-deficiency chlorosis and soybean cyst nematode in minnesota soybean fields. Plant and Soil Journal. 299:131-139. doi: 10.1007/s11104-007-9370-x Interpretive Summary: Soybean yields can be reduced if plants are affected by nematodes and fungi that attack plant roots and by a lack of iron, an important nutrient needed by the plants. These problems often coexist in the same fields in the North Central region of the United States. Soybean cultivars with resistance to soybean cyst nematode, root rot, and iron-deficiency chlorosis, alone or in combination, were evaluated in commercial fields in central and southern Minnesota to determine if they could effectively manage the problems and minimize associated yield loss. During this work we found that complex relationships between the problems existed. For example, cultivars with resistance to soybean cyst nematode had less root rot and less yellowing due to iron deficiency, suggesting that roots affected by the nematode were more likely to be affected by root rot fungi and less likely to absorb iron. Root rot resistance was associated with reduced iron deficiency symptoms, and resistance to iron deficiency was associated with larger and more damaging populations of soybean cyst nematode. Because of these complex relationships, yield responses to the resistance traits varied from field to field and it was not possible to develop a set of all-purpose recommendations for growers in the North Central region. Instead, the results underscore the importance of having specific knowledge about the intensity of the problems in an individual field before recommendations can be made for effective management at that location.
Technical Abstract: Experiments were conducted in six commercial fields differing in severity of iron-deficiency chlorosis (IDC), soybean cyst nematode (SCN), and root rot in Waseca, Lamberton, and Morris, Minnesota. Each experiment was a randomized complete block with a factorial treatment design including 24 cultivars with or without traits of resistance to SCN, root rot (Phytophthora sojae), and IDC. The study illustrated the interactive effects of the three defensive traits on the diseases and soybean yields. Resistance to SCN suppressed IDC and root rot, suggesting SCN increased IDC and root rot. Resistance to Phytophthora root rot also reduced IDC severity. Resistance to IDC apparently increased SCN reproduction due to better soybean plant growth. Yield response to the defensive traits depends on the pressures of the diseases in a field. When SCN and IDC problems were both present in a field, deploying SCN-resistance was the best solution to the problems. However, SCN-resistance suppressed soybean yields when they were 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 the SCN-resistant cultivars in the SCN-infested sites. Phytophthora-resistance did not affect yield at any of the sites except one where it suppressed yield. Effective use of the defensive traits for management of IDC, SCN, and root rot requires specific knowledge of the disease problems present in a field.