Location: Soybean and Nitrogen Fixation Research
Project Number: 6070-21220-070-041-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Oct 1, 2023
End Date: Sep 30, 2024
Objective:
Almost 90% of US soybean production occurs under rain-fed conditions with no option for irrigation. As the risk continues to grow for increasing incidences in droughts across the U.S., so does the threat to U.S. soybean production. According to a recent report based on data collected from the USDA’s Risk Management Agency, insurance payments to farmers due to drought increased by more than 400% between 1995 and 2020 to $1.65 billion. Overcoming the devastation of drought is a cornerstone of sustainable soybean production. The mission of this project is to develop the research tools and genetic resources needed to make U.S. farms drought resilient. To this end, farmers need performance data for commercial varieties under drought to help make informed varietal choices to increase drought resiliency on their farm. As drought stress becomes more prevalent the protection offered by drought-resiliency could have an even greater impact on soybean yield in the future. The bottom line is that every bushel saved from drought stress by using tolerant varieties would directly translate into net income for U.S. soybean farmers.
Objectives to which ARS investigator will contribute:
1. Evaluate commercial varieties for drought tolerance and yield in maturity groups (MG) V through VIII.
2. Develop and evaluate new drought-tolerant breeding stock for potential release, so that commercial breeding programs can develop better drought-tolerant varieties.
3. Develop novel breeding lines which combine drought tolerance with high oleic oil and high protein meal.
Approach:
Objective 1: Commercial varieties will be selected in conjunction with the local North Carolina Official Variety Testing (OVT) Program and private breeders. In 2024, ~120 commercial varieties will be evaluated at the Sandhills Research Station in NC. The Sandhills Research Station has deep, sandy soils which provides a unique opportunity to investigate plants under drought stress. Commercial lines will be evaluated using a randomized complete block design with four replications. Known fast wilting and slow wilting lines will be included as checks. All tests will be irrigated at planting to ensure good germination and plant stands. All lines will be evaluated for visual wilting scores and yield to determine the level of drought tolerance. Wilting scores will be recorded on a scale of 1-5, with 1 being no damage and 5 being severe wilting and plant damage. Our results from screening over 100 commercial varieties in 2022 showed only 10-20% of the varieties exhibited slow wilting, indicating the usefulness of continued screening of commercial varieties under drought stress conditions
Objective 2: Advanced breeding lines will be evaluated for yield performance and drought tolerance in replicated drought tests at the Sandhills Research Station in 2024. Lines that showed high yield under both dryland and irrigated field conditions and revealed good slow-wilting traits under water stress in 2023 will be included. In 2023, evaluation will include more than 50 new lines derived from 2 wild soybean accessions, retesting of more than 40 new USDA breeding lines derived from previously identified drought tolerant breeding stock and retesting of an additional 50 USDA breeding lines which have exhibited drought tolerance in previous years. For evaluation in 2023 and 2024 lines will be planted in 12’ 4-row plots in dryland and irrigated conditions. Wilting scores will be recorded in the dryland planting set only. Yield and other agronomic traits will be recorded in both conditions.
Objective 3: In 2022, initial crosses were made between slow wilting and high protein and high oleic breeding lines. F1 seed were sent to a USDA Winter Nursery in Puerto Rico in December of 2022. F2 and F3 plants will be grown in NC in the summers of 2023 and 2024. respectively and subjected to the modified single seed descent breeding method. F4 plants will be grown in 2025, selected plants will be harvested and subjected to GC analysis or NIR analysis as appropriate. New hybrids will also be developed in 2023 and 2024 to expand this process.
