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Title: Screening soybean germplasm and commerical varieties for resistance to Phomopsis seed decay: results from 2012 trials

item Li, Shuxian
item SCIUMBATO, GABE - Mississippi State University
item CHEN, PENGYIN - University Of Arkansas
item SUN, SHI - University Of Arkansas
item RUPE, JOHN - University Of Arkansas
item HOLLAND, ROBERT - University Of Arkansas
item STEGER, ADELE - University Of Arkansas

Submitted to: Southern Soybean Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/13/2013
Publication Date: 3/14/2013
Citation: Li, S., Sciumbato, G., Chen, P., Sun, S., Rupe, J., Holland, R., Steger, A. 2013. Screening soybean germplasm and commerical varieties for resistance to Phomopsis seed decay: results from 2012 trials. Southern Soybean Conference Proceedings. 21.

Interpretive Summary:

Technical Abstract: Soybean Phomopsis seed decay (PSD) causes poor seed quality and suppresses yield in most soybean production areas of the United States. In 2009, PSD caused a yield loss of over 12 million bushels in 16 southern states. The disease is primarily caused by Phomopsis longicolla along with other Phomopsis and Diaporthe spp.. Very few soybean cultivars currently available for planting in the US. have resistance to PSD. To identify new sources of resistance to PSD and develop high yielding cultivars and breeding lines with PSD- resistance, a multistate and multiyear research project entitled “Screening germplasm and breeding for resistance to Phomopsis seed decay” funded by the United Soybean Board with support from the USDA-ARS was initiated in 2009. A total of 135 selected soybean germplasm lines collected from 28 countries with maturity groups III, IV, and V were field screened by natural infection in 2009 at Arkansas, Mississippi, and Missouri. Seeds were harvested from each plot and tested for percent seed infected by Phomopsis spp., germination rate, and visual quality. Based on the results in 2009, 42 lines with most resistant or susceptible reactions were selected and evaluated in 2010, 2011, and 2012 with Phomopsis inoculated and non-inoculated treatments. Preliminary results from 2012 trials showed that seed infection by a variety of soybean fungal pathogens was notably higher in 2012 than in 2010 or 2011. Significant differences in seed infection by P. longicolla were observed among soybean lines with some lines having no infection while others had levels as high as 85%. These differences among lines also were reflected in visual seed quality and seed germination. In general, inoculated plots had higher seed infection than the non-inoculated plots. Soybean lines with low seed infection, good visual quality, and high germination rate at all locations and in four years will be selected and used to develop breeding or mapping populations for resistance to PSD. Another study funded by the Mississippi Soybean Promotion Board, evaluated 16 commercial varieties for resistance to PSD with inoculated and non-inoculated treatments and two harvest times at R8 and R8+2 weeks stages (normal vs. delayed harvest) in Mississippi in 2012. Those 16 varieties were selected based on the data from seed assays of 50 commercial varieties in 2011. Several varieties were identified with low disease incidence and good seed quality. An update on other research related to PSD and its causal pathogen P. longicolla will also be presented and discussed.