Identification of genetic mechanisms for tolerating periods of drought is critical to sustaining soybean production. Farmers need help with drought. This research is designed to help the farmer in 3 phases. 1) Farmers need documented performance data for commercial varieties under drought. We will yield test commercial varieties in multiple states in maturity groups III through VIII at drought prone sites. Results will aid farmers with variety choices and guide new public-private breeding efforts to fix the drought problem, 2) Farmers need new drought-tolerant breeding stock so that commercial breeding programs can develop better drought-tolerant varieties. The public breeders in this project have a wealth of advanced drought-tolerant materials in their breeding pipeline. New materials will be evaluated and released to commercial breeders based on yield performance under drought. 3) Farmers need basic work to support new drought-tolerant variety release. We will conduct QTL mapping, MAS, and, GWAS of field-based slow-wilting and deep rooting. A novel source of superior ‘water use efficiency’ discovered recently in the field (via direct measurements of leaf gas exchange) will be validated. Impact of drought and slow wilting on yield and seed protein will be assessed.

1) Annual screening of commercial varieties in maturity groups III through VIII for yield and slow wilting under stress.
2) Follow-up analysis and additional screening of commercial varieties under irrigated and non-irrigated conditions.
3) Yield testing and release of new publicly-developed drought-resistant breeding lines.
4) Impact of the Slow-Wilting trait and other drought tolerance traits on seed yield under drought stress and high yielding conditions.
5) Conduct basic work to support cultivar and germplasm release.

• Preliminary report on yield performance of commercial cultivars by the end of year 2 and an expanded report at the end of year 3.
• Release of at least one new germplasm by the end of year 3.
• Quantification of the impact of the slow-wilting trait on seed yield under stress in year 3.
• Quantification of the impact of drought and the slow-wilting trait on seed protein content under stress by the end of year 3.
• Completion of a GWAS study on slow wilting by year 3.
• Backcrossing at least one generation of QTLs into elite varieties using MAS in year 3.
• Quantification of phenotypic data for QTL mapping for slow-wilting by the end of year 3.
• Complete the survey of drought tolerant breeding stock for intrinsic water-use efficiency and report results by the end of year 3. Identify high- and low- intrinsic water-use efficiency progeny from Fiskeby III by the end of year 3.
• Report on the drought threshold for slow-wilting trait advantage by the end of year 3.
• Report on the relations between photosynthesis, leaf water potential, and slow wilting by the end of year 3.

Update:
Identification of genetic mechanisms for tolerating periods of drought is critical to sustaining soybean production. Farmers need help with drought. This research is designed to help the farmer in 3 phases. 1) Farmers need documented performance data for commercial varieties under drought. We will yield test commercial varieties in multiple states in maturity groups III through VIII at drought prone sites. Results will aid farmers with variety choices and guide new public-private breeding efforts to fix the drought problem, 2) Farmers need new drought-tolerant breeding stock so that commercial breeding programs can develop better drought-tolerant varieties. The public breeders in this project have a wealth of advanced drought-tolerant materials in their breeding pipeline. New materials will be evaluated and released to commercial breeders based on yield performance under drought. 3) Farmers need basic work to support new drought-tolerant variety release. We will conduct QTL mapping, MAS, and, GWAS of field-based slow-wilting and deep rooting. A novel source of superior ‘water use efficiency’ discovered recently in the field (via direct measurements of leaf gas exchange) will be validated. Impact of drought and slow wilting on yield and seed protein will be assessed.

This new project was approved to start October 1. As of December 14, the main progress to report is that the agreement between USB and USDA-ARS is signed and active. Subcontracts between the six universities in the project and USDA-ARS have been drafted and will be active soon.

We intend to have a meeting in February or March to discuss research details for 2018. This meeting will be coordinated with Rich Joost.

Updated December 4, 2018:
Farmers need help with drought: 1) Farmers need documented performance data for commercial varieties under drought. 2) Farmers need new drought-tolerant breeding stock, so that commercial breeding programs can use them to develop better drought-tolerant varieties. 3) Farmers need basic research to support new drought-tolerant variety release.

This new project started October 1. As of December 14, the main progress to report was that the agreement between USB and USDA-ARS was signed & subcontracts between the six universities and USDA-ARS were almost finalized.

March 15 Report:
Because of the Oct. 1 start date, we have not yet had the opportunity to conduct field studies or collect data. Most of our progress has consisted of research coordination meetings, planning for summer 2018, data analysis, publications, and presentations. Please see below. I will provide descriptions of specific experiments in the June report.

Publications:
Bagherzadi, Laleh, T.R. Sinclair, M. Zwieneicki, F. Secchi, W. Hoffman, T.Carter, and T.Rufty. 2017. Assessing water-related plant traits to explain slow wilting PI 471938. J. Crop Improvement. 31:400-417.

Mandeep Riar, P. Cerezini, A. Manandhar, T. R. Sinclair, Z. Li, and T. E. Carter, Jr. 2017. Expression of Drought-Tolerant N2 Fixation in Heterogeneous Inbred Families derived from PI 471938 and Hutcheson Soybean. Crop Sci. 58:364-369.

Kaler, S., J.D. Ray, W.T. Schapaugh, C.A. King, and L.C. Purcell. 2017. Genome-wide association mapping of canopy wilting in diverse soybean genotypes. Theor. Appl. Genet. 130:2203–2217. DOI 10.1007/s00122-017-2951-z.
Clinton J. Steketee, William T. Schapaugh, Thomas E. Carter Jr., and Zenglu Li. 2018. Genome-wide Association Analysis and Linkage Mapping Reveal Genomic Regions Controlling Canopy Wilting in Soybean. Frontiers in Plant Science (In review)

Miles Ingwers, Clinton J. Steketee, Sushil K. Yadav, and Zenglu Li. 2018. Carbon isotope composition is correlated with above-ground biomass accumulation and foliar nitrogen concentration under low and high soil moisture availability in soybean. Environmental and Experimental Botany (Submitted)

Heng Ye, Manish Roorkiwal, Babu Valliyodan, Lijuan Zhou, Pengyin Chen, Rajeev Varshney, Henry T. Nguyen. 2018. Genetic diversity of root system architecture in response to drought stress in grain legumes. Journal of Experimental Botany (In Press)

Presentations:
Carter, T.E. Invited presentation: ‘More Crop for the Drop- Developing Drought Tolerant Soybeans’. 19th Annual Customer/Partner Dialogue Workshop, USDA-ARS Coastal Plains Soil, Water, and Plant Research Center, Florence, SC, March 15th, 2018

Steketee, C.J., W.T. Schapaugh, T.E. Carter Jr., and Z. Li. ‘Discovery of genomic regions and germplasm to improve drought tolerance in soybean’. Soybean Breeder’s Workshop. Feb. 2018. St. Louis, MO. (Poster)
Steketee, C.J., W.T. Schapaugh, T.E. Carter Jr., and Z. Li ‘Identification of genomic regions and germplasm to improve drought tolerance in soybean’. GA/FL Small Grains/Soybean Expo. Jan. 2018. Perry, GA. (Poster)
Fallen, Ben. Invited Presentation: “Breeding for Drought Tolerate Varieties.” South Carolina Crop Improvement Association Board Meeting. Columbia, SC. 02/22/18

Fallen, Ben. Invited presentation: “Evaluating and Improving Drought Tolerance Across the Carolinas.” South Carolina Young Farmer and Agribusiness Association, South Carolina Promotion Board and the South Soybean Board Meeting. Charleston, SC. 01/20/18.

Henry T. Nguyen. ‘Development of Climate Resilient Soybeans’ Plant & Animal Genome XXVI, San Diego, CA, USA. January 13-17, 2018,

Henry T. Nguyen. ‘Natural Variation and Genetic Regulation of Root Architecture and Plasticity in Soybean’. International Symposium on Crop Roots and Rhizosphere Interactions, Yangling, China. October 9-13, 2017.

Additional Research Highlights:
A detailed report of experimental plans and specific tests for 2018 will be included in the June report. Much of the current planning has to do with taking inventory of seed stocks, checking germs, and seeing which populations have enough seed for sharing and testing at multiple locations. Below are research highlights in addition to those items above.

New Asian Slow Wilting Germplasm Identified in GA. Researchers at the University of Georgia (in collaboration with Kansas State Univ. and USDA-ARS at Raleigh) have just identified 10 new Asian soybean types possessing the slow canopy-wilting trait. 200 exotic soybean types were evaluated over four rainfed environments to identify the new genetic materials. The new sources of the slow-wilting trait identified through this research (primarily Chinese accessions) expand our capability to improve drought tolerance in soybean varieties.

New Group V Germplasm Releases in AR: In 2017, the University of Arkansas released two high-yielding, drought-tolerant germplasm lines, R10-2436 and R10-2710. During six years of evaluation under moderate drought stress, R10-2436 yielded 48.2 bu/ac and R10-2710 produced 46.5 bu/ac as compared to the maturity group V check mean of 41.7 bu/ac. in Stuttgart, AR. Both lines carry the prolonged N-fixation trait as one mechanism of tolerance under drought. The registration manuscript of these two releases is ready and in the process of submission to the Journal of Plant Registration.

Commercial Soybean Varieties will be Screened for Drought Reaction in Multi-state Trials in 2018. USB team drought members are coordinating with State Variety Trials to screen more than 100 commercial varieties for drought response. Researchers in NC, SC, AR, KS, and MO will be growing elite commercial material in comparison to public reference types in replicated trials at drought prone sites in 2018. Results will be compared with those obtained in 2015 and 2016 from these sites to assess the level of drought resistance in commercial breeding and where public research needs to be applied.

Coordination and Exchange of Public Breeding Materials for Drought Tolerance Testing in 2018. Researchers in NC, SC, and KS are opening up their drought-prone field sites for collaborative screening trials in 2018. Extensive cooperative planning is underway. Physiologists Kent Burkey and Anna Locke, plus soybean breeders Ben Fallen, Lenado Mozzoni, and Zenglu Li will be testing their materials with Tommy Carter at the Sandhills Research Station in NC. Carter and Li will be testing their materials at the Clemson Station at Florence with Ben Fallen. Soybean breeder Bill Schapaugh at K-State will be growing trials at his drought prone sites for most of the other team members including Carter, Li, Nguyen, and Chen. Details will be finalized by the end of March.

Updated December 4, 2018:

View uploaded report

Updated December 4, 2018:

View uploaded report

Updated November 16, 2018:
use efficiency.
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View uploaded report

Farmers need access to a wide variety of drought tolerant cultivars. As extreme weather challenges are increasing, breeding efforts need to continue to ‘push the needle’ to cope with these challenges.

• At least one commercial breeder visits our commercial drought performance trials to personally evaluate commercial varieties during the 2018 growing season, assuming that drought and canopy wilting develop.
• At least 5 farmers visit at least one of our commercial drought performance trials to personally evaluate commercial varieties during the 2018 growing season, assuming that drought and canopy wilting occur
• At least one company assists this project in evaluating new public breeding lines during the 2018 growing season.
• At least one new drought tolerant germplasm is released by the end of 2019.
• At least one drought-tolerant commercial variety is identified and communicated to farmers in 2019, assuming that drought and canopy occur.