2012 Annual Report
1a.Objectives (from AD-416):
The objective to evaluate the resistance of public and private soybean varieties and breeding lines to the most serious diseases present in the southern United States.
1b.Approach (from AD-416):
The Delta Research and Extension Center, Mississippi Agricultural and Forestry Experiment Station, Stoneville, Mississippi, will obtain seed of the entries in the Mississippi State Soybean Variety Trials, which average 225 entries in soybean Maturity Groups III-VII. Seed of the breeding lines from the USDA soybean breeder at Stoneville will also be obtained. These entries and breeding lines will be screened for resistance to the following diseases: 1. STEM CANKER - The toothpick method of inoculation will be used to evaluate resistance to this disease. 2. FROGEYE LEAF SPOT - Spores from selected races which are prevalent in Mississippi will be sprayed on soybeans to be evaluated in mist chambers and in field studies. 3. CERCOSPORA BLIGHT, PURPLE LEAF STAIN AND POD ROT - The leaves of the entries will be inoculated with spores in mist chamber and field studies. Mature green pods will be placed in humidity chambers and inoculated with spores of the fungus. 4. BLACK ROOT ROT - Seed of the entries will be planted in potting mix infested with the fungus. Root ratings will be made 6 weeks after planting. Other foliar diseases of soybean will be evaluated if present in field plots.
Seed were obtained from all of the entries in the Mississippi State Soybean Variety Trials. This included seed of Maturity Groups IV to VI and both Roundup Ready and Conventional seed. Greenhouse, growth chamber, and field trials were conducted to determine the resistance of the entries to certain diseases.
Goal One: Evaluation of resistance to stem canker. All of the entries in the 2011 trials have been evaluated and the entries in the 2012 have been planted and inoculated.
Goal Two: Evaluation of resistance to frogeye leaf spot: All of the entries in the 2011 trials have been evaluated in field studies and the research scientists are finishing up the greenhouse evaluations. All of the entries in the 2012 trials have been planted and inoculated at least once with the frogeye fungus.
Goal Three: The entries in the 2012 trials will be inoculated with the purple leaf fungus at the R5 growth stage. Mature green pods will be inoculated to evaluate purple pod rot.
Goal Four: Evaluation of resistance to black root rot: All of the entries in the 2011 variety trials have been inoculated and rated for resistance in growth chamber trials. We have begun to evaluate the entries in the 2012 trials.
Goal Five: Evaluation of resistance to soybean rust. A trial was planted late in 2011 to evaluate soybean rust resistance. However, no rust developed in the trials.