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EVALUATING SOYBEAN CULTIVARS AND GERMPLASM FOR RESISTANCE TO SOYBEAN CYST NEMATODE
EXECUTIVE SUMMARY
NORTH DAKOTA SOYBEAN COUNCIL
JUNE 2020
Dr. Guiping Yan, Principal Investigator, Dept. Plant Pathology, NDSU
Co-investigators: Dr. Ted Helms, Dept. Plant Sciences, NDSU and Dr. Sam Markell, Dept. Plant Pathology, NDSU
Research Conducted
Eighty-one soybean lines (germplasm of maturity group 00 to 1, breeding lines, and commercial cultivars) each in four replicates were screened against SCN HG type 2.5.7, and eighty soybean lines (germplasm of maturity group 00 to 1 and commercial cultivars) each in four replicates were screened for SCN HG type 0 isolated from soybean fields in North Dakota. Each plant was inoculated with 2,000 SCN eggs and grown in a growth chamber for 35 days. The female index was calculated for each of the soybean lines by comparing the number of white females (cysts) with that formed on the susceptible soybean Barnes, then categorized for resistance reactions.
Why the research is important to ND soybean farmers
Soybean cyst nematode (SCN; Heterodera glycines) is a major yield-limiting factor of soybean. In 2015 and 2016, a more virulent form (HG type 2.5.7) that reproduced well on PI 88788 was detected in soybean fields in ND. The new forms have higher levels of virulence and are able to overcome the resistance that is commonly used for control. The shift in SCN populations has led to a decrease in resistance in soybean cultivars derived from PI 88788 elsewhere. Hence, it is imperative to screen soybean cultivars and lines for identifying resistance against the new virulent type in ND.
Final findings of the research
Out of 81 soybean germplasm, breeding lines, and commercial cultivars tested for HG type 2.5.7, two lines were resistant, ten were moderately resistant, 27 were moderately susceptible, and 42 were susceptible. For HG type 0, out of 80 lines, one line was resistant, six were moderately resistant, 46 were moderately susceptible, and 27 were susceptible. Therefore, out of all the entries tested, 15% were resistant or moderately resistant to HG type 2.5.7, and 9% were resistant or moderately resistant to HG type 0, but none of them showed resistance to both the populations tested.
Benefits/Recommendations to North Dakota soybean farmers and industry
Three resistant soybean cultivars and lines were identified in this research. The important soybean entries identified will be re-tested to confirm their resistance reaction. The research findings are useful to navigate the use of resistance sources for farmers and the resistance sources that should be introduced to the soybean breeding programs to develop new cultivars with resistance to the common or new SCN virulent population.