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United States Department of Agriculture

Agricultural Research Service

Research Project: Strengthening Public Corn Breeding to Ensure That Organic Farmers Have Access to Elite Cultivars: Stress Nurseries

Location: Corn Insects and Crop Genetics Research

Project Number: 5030-21000-063-03
Project Type: Specific Cooperative Agreement

Start Date: Jun 06, 2011
End Date: Aug 31, 2014

Objective:
1) Cooperate in the breeding effort through stress evaluations, 2) participate in outreach activities, and 3) cooperate in planning, execution, and reporting of experiments and breeding plans.

Approach:
Stress evaluations will include the following evaluations. Cold germ selection: each year as many as 50 S0 bulk (2,500 seeds per entry) breeding crosses will be screened for their ability to germinate after prolonged exposure to 40 degrees F in saturated rag rolls for approximately three weeks. Individual survivors (target 250 per breeding cross) will be identified and then shipped to breeder's nurseries for transplanting, further selection, inbreeding and testing. Plots will be scored visually on a 0-9 scale for damage to late season plant integrity in an organic nursery near Clinton, Illinois. Central Illinois is an excellent environment for selecting against leaf disease and root lodging due to combinations of wind, rain, Western corn rootworm and Anthracnose. This will provide information on the ability of the breeding lines to tolerate multiple stressors. Furthermore, each year self-pollinations will be made within the top 5% of the rows in the stress nursery (150 most promising rows of the best early segregating S1, S2, S3 generations or narrow synthetics) in order to identify individual plants most tolerant to multiple stressors. These plants will be returned to the breeders for more work. Treatments include: accelerated aging, notes on stand establishment, vigor, uniformity and any other stand related abnormalities, and root & stalk lodging. Plots will be visually assessed for percentage of plants that are root or stalk lodged and for the severity of the leaf diseases. Artificial inoculation will occur for gray leaf spot, Anthracnose leaf blight, northern leaf blight, northern leaf spot, southern leaf blight, and common rust. Stewarts Wilt occurs naturally each year as there are enough flea beetles to spread it. Starting the last week in August, plots will be visually rated for percentage of leaf area still green (SG) every week. Sums of the percent green tissue for 2, 3, or 4 ratings will be used to characterize entries by computing areas under disease progress curves. Artificial inoculation with stalk rot: within 3 days of plots reaching 50% silk, the last ten plants in each plot will be inoculated with organisms in the soil by dipping a nail mounted on a stick into the soil and then forcibly injected into the center of the first elongated internode above the ground. Plots will be scored for premature death and late season plant integrity on a 0-9 scale.

Last Modified: 10/31/2014
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