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Outcomes of Research on Soybean Cyst Nematode Resistance (SCN), Genetic Diversity, Drought, Remote Sensing and Variety Development
SCN Breeding and Management
Our evaluations for SCN resistance have characterized the level of SCN resistance in soybean experimental lines and commercial varieties. This will assist soybean growers in making informed variety selection decisions that impact SCN management, and aid our breeding program in the selection and potential release the of the most resistant material in our program.
Genetic Diversity
We continue to evaluate plant introductions to identify new genetic variability for response to drought and heat stress, seed composition and improved yield potential. The past several seasons, we have conducted evaluations on over 2500 maturity groups 3 through 10 plant introductions. Data collected on these introductions included traits such as: maturity, lodging, height, seed yield, shattering, 100 seed weight, seed quality, seed protein and oil concentrations, and canopy wilting scores. Based on these evaluations we develop populations involving plant introductions that have not contributed to the genetic improvement of US soybean varieties. The goal of using these parents is to increase the genetic diversity of US germplasm to increase, or at least, maintain genetic gain.
Remote Sensing
Canopy reflectance represents a high-throughput opportunity for phenotyping in soybean breeding. We continue to develop models utilizing canopy reflectance and canopy thermal properties to estimate relative soybean maturity, seed yield, maturity, drought stress, and disease resistance. The focus on 2017 and 2018 was obtaining remote sensing data on SDS screening trials, on our progeny rows and on germplasm and varieties evaluated for drought stress. All spectral data collected in 2017 and 2018 was accomplished using unmanned aerial vehicles (UAVs). Selections based on data collected using the UAVs were made in 2017 and 2018 and are being evaluated in replicated yield trials to characterize the benefits of using this technology to improve selection efficiency.
Slow wilting QTL analysis
Our assessment of slow wilting in genotypes under drought stress may help improve drought tolerance in soybean. In work with the Univ. of Arkansas, we characterized canopy wilting of 373 maturity group (MG) IV soybean genotypes to identify new and previously reported QTLs for canopy wilting. Over 60, environment-specific significant SNP – canopy wilting associations were identified. Some of the associations were located near previously reported chromosomal regions associated with canopy wilting, and other associations were new. This information will be important for pyramiding beneficial genes into the same genotype, and identifying parents to use in developing populations with improved drought tolerance.
Commercial wilting trials
Seventy-five maturity group 4 and 5 soybean genotypes, consisting of commercial varieties and checks, were evaluated for wilting in replicated trials at Salina KS in 2018. These evaluations included several of the new Roundup Ready Xtend soybean varieties. Between two to four wilting scores were taken on each plot during late vegetative and early reproductive growth. In addition to the wilting ratings, seed yield, maturity, lodging and plant height were collected on all plots. The plants experienced severe drought and heat stress during late vegetative and early reproductive growth. Cultivar wilting scores ranged from near 0 to 65 across rating times. A score of 0 indicated no wilting present and a score of 25 indicated moderate wilting and rolling of leaves in the top of the canopy. Wilting scores of the slow-wilting checks ranged from 0 to 5, while wilting scores of the fast-wilting checks averaged from 40 to 50. The most severe rating of a cultivar on any day was 65, indicating severe leaf rolling throughout the canopy. Most of the commercial soybean varieties possessed wilting ratings similar to, or more severe, than the fast wilting checks, which possessed average wilting scores around 20. However, one commercial group 4 variety, and 2 commercial group 5 varieties possessed wilting scores similar to the slow wilting checks. Out of these 3 commercial varieties which exhibited slow-wilting characteristics in KS, the yield of the group 4 variety, and one of the group 5 varieties were similar in seed yield to the highest yielding entries across the two locations. Commercial Wilting Trials were evaluated in Missouri, Arkansas, South Carolina, Georgia and North Carolina. Data from these trials will be used to develop a robust assessment of the wilting and drought resistant characteristics of currently available commercial experimental soybean varieties and help guide our breeding activities.
Variety Development/Genetics
This project enabled the development of 90 new breeding populations, and advance over 300 populations in the F1, F2, F3, F4 and F4:5 generations. Parents used to create these populations in 2018 were selected for their yield potential, drought tolerance, herbicide resistance (Roundup Ready 1 and STS), seed protein content, oil composition, disease resistance (primarily SCN and Soybean Sudden Death Syndrome), and genetic diversity.
This project enabled the evaluation of about 5000 genotypes in over 16,000 plots in Kansas. Over 1600 K-lines were evaluated in our preliminary trials. Over 180 K-lines were evaluated in our KS advanced yield trials. Over 600 (including 28 K-lines) breeding lines from programs across the country were evaluated in our KS Uniform Tests and Uniform Preliminary yield trials. Over 700 genotypes, (experimental breeding lines and plant introductions) were evaluated in our drought, remote sensing, and diversity yield trials.
This project enabled the release by The Kansas Agricultural Experiment Station of KS4949N, a late group 4 variety. This is a conventional variety that can be used for commercial production, and as a parent by other plant breeders for the development of new varieties.
Opportunities for Training and Professional Development
One graduate student worked on objectives related to this project in Agronomy, and two others in Bio and Ag Engineering utilized the field plots developed and evaluated through this project for research on remote sensing.
Dissemination of Results
Peer-reviewed publications, extension publications, news releases, and experiment station reports, field days, extension meetings and tours are used to share the results of this project. Web pages have been developed to disseminate information on new releases and germplasm and pests. Distribution of results of genotype characterization for resistance are published online. Distribution of SCN survey results to cliental will provide much-needed information for making informed decisions by producers regarding variety selections for SCN management and by soybean breeders for the development of varieties with improved levels of resistance. Publications in peer-reviewed publications in 2018 included:
Avjinder S. Kaler, Jeffery D. Ray, William T. Schapaugh, Antonio R. Asebedo, C. Andy King, E. E. Gbur, and Larry C. Purcell. 2018. Association mapping identifies loci for canopy temperature under drought in diverse soybean genotypes. Euphytica 214:135, https://doi.org/10.1007/s10681-018-2215-2.
Maduraimuthu Djanaguiraman, William Schapaugh, Felix Fritschi, Henry Nguyen and P.V. Vara Prasad. 2018. Reproductive success of soybean cultivars and exotic lines under high daytime temperature. Plant, Cell and Environment. https://doi.org/10.1111/pce.13421.
Diers B.W., Specht J., Rainey K.M., Cregan P., Song Q., Ramasubramanian V., Graef G., Nelson R., Schapaugh W., Wang D., Shannon G., Mchale L., Kantartzi S.K., Xavier A., Mian R., Stupar R.M., Michno J.-M., An Y.-Q.C., Goettel W., Ward R., Fox C., Lipka A.E., Hyten D., Cary T., Beavis W.D. 2018. Genetic architecture of soybean yield and agronomic traits. G3 8: 3367-3375.
Xavier A., Jarquin D., Howard R., Ramasubramanian V., Specht J.E., Graef G.L., Beavis W.D., Diers B.W., Song Q., Cregan P.B., Nelson R., Mian R., Grover Shannon J., McHale L., Wang D., Schapaugh W., Lorenz A.J., Xu S., Muir W.M., Rainey K.M. 2018. Genome-wide analysis of grain yield stability and environmental interactions in a multiparental soybean population. G3 8: 519-529.