Location: Wheat, Sorghum and Forage Research2021 Annual Report
1. Develop best management practices for annual and perennial grasses to increase livestock production, provide biomass feedstocks for bioenergy, and preserve and maintain the nation’s natural resources. (NP215 1A, 2C, 4B, 4C) 2. Develop new forage and biomass germplasm and cultivars for central U.S. growing conditions. (NP215 1A, 2C) 3. Identify molecular, biochemical and plant characteristics that impact livestock and bioenergy production to develop improved breeding criteria and improved management practices. (NP215 1A, 2C)
Project objectives are to develop best management practices for annual and perennial grasses for livestock production, provide feedstocks for bioenergy, develop new forage and biomass cultivars for the central U.S., and identify molecular, biochemical, and plant characteristics that impact livestock and bioenergy production and complement breeding and management research. Perennial grass breeding techniques will be refined to design improved cultivars. Improved management methods will be developed to fully utilize the genetic potential of new cultivars by enhancing establishment, yield, and utilization by livestock and by the bioenergy industry. Molecular biology and biochemistry/physiology information will be utilized to improve breeding and management products. The project is a continuation of a long-term perennial grass research program with plant materials, management, and related studies in various stages of development and completion. Research will be conducted on C3 (cool-season) and C4 (warm-season) perennial grasses, and C3 annual grasses. All are needed to maximize the length of the growing season and more fully utilize available land. Switchgrass, big bluestem, and indiangrass are the primary C4 species being evaluated for use in livestock and/or bioenergy production systems. Triticale, a winter annual, will be developed for forage/cover crop use as a double-crop option with early spring grazing and improved soil conservation. New technologies from this research, when utilized on 6 million hectares in the Midwest, could produce biofuels for 15 million cars, increase beef production per hectare by 10%, and increase early spring forage production by 6 million animal unit months.
The project has three main components: management, breeding, and molecular biology/biochemistry. This project leads the development of switchgrass into a biomass energy crop and has numerous collaborations. This project has developed most of the grasses and associated management information used for grassland reseeding in the central U.S., and much of the management information for switchgrass grown as a biomass energy crop. Fundamental science has been developed on cell wall properties and their genetic control, and information and data are being used extensively in switchgrass genomics. The overall objectives of this continuing long-term project are to develop improved perennial grasses, management practices, and technologies for use in grazing lands and biomass energy production systems in the central U.S. Over the next five years, the following specific objectives will be addressed. (1) Develop best management practices for annual and perennial grasses to increase livestock production, provide biomass feedstocks for bioenergy, and preserve and maintain the nation’s natural resources; (2) Develop new forage and biomass germplasm and cultivars for central U.S. growing conditions; and (3) Identify molecular, biochemical, and plant characteristics that impact livestock and bioenergy production to develop improved breeding criteria and improved management practices. Objective 1 research continued on developing best management practices for annual and perennial grasses to increase livestock production, provide biomass feedstocks for bioenergy, and preserve and maintain the nation’s natural resources. In Sub-objective 1A, integrated crop-livestock systems for the Great Plains that include smooth bromegrass, switchgrass, triticale, wheat, rye, corn, and soybeans are being evaluated. The smooth bromegrass has produced steer average daily gains (ADG) of up to 4 lbs/head/day and the switchgrass components have produced ADG of about 1 lb/head/day. The new warm-season grass mixture pasture (formerly Shawnee switchgrass) was seeded in 2021 to provide future increased animal performance. The Liberty switchgrass pasture was sprayed with glyphosate in early spring to reduce cool-season grass invasion then interseeded with Liberty to improve stand density. Grazing wheat, rye, and triticale in the spring before soybeans produced an ADG of 1.4 to 3.0 lbs/head/day in 13 grazing days. In Subobjective 1B, 2021 represents the 24th year of growing switchgrass and no-till corn on marginally productive cropland. To date, nitrogen (N) and harvest management have had a significant impact on biomass yield, soil organic carbon (SOC), and greenhouse gas emissions (GHG). This long-term field study is the first to demonstrate that annual crop and perennial grass systems respectively maintain or mitigate atmospheric GHG contributions during the agronomic phase of bioenergy production, providing flexibility for land-use decisions on marginally productive croplands. In Subobjective 1C, the field-scale production of Liberty switchgrass, big bluestem, and a low-diversity warm-season grass mixture continues with reduced N rates to evaluate biomass and GHG emissions. Additionally, ‘Independence’, a new switchgrass cultivar, was planted at the site in spring 2019. Since 2012, this marginally productive site in eastern Nebraska has reliably produced 5 U.S. tons/acre per year to meet potential feedstock demands for the bioeconomy. Objective 2 research continued on developing new forage and biomass germplasm and cultivars for the central U.S. In Subobjective 2A, five perennial grass species are being bred for both livestock and bioenergy production systems. Breeding values of both parents and progeny have been quantified in multi-generational analyses. A genomic selection framework using quantitative trait locus mapping, classical genetics, physiology, transcriptomics, and virology is being evaluated to maximize the genetic potential of switchgrass for biomass and lignin yield and disease resistance. Two progeny tests of switchgrass have been planted in the field. Harvests of 4 bromegrass progeny tests have been completed and advancement made by combining two populations in a crossing block nursery. Three open-pollinated crossing nurseries of Indiangrass have been field-planted, each by combining two different populations. Two types of regional trials were planted, one for cultivar and germplasm release and one for evaluating genotype by environment interactions. Second generation of three propagation nurseries were planted for potential release of switchgrass cultivars. In Subobjective 2B, field evaluations have been initiated to determine the relative importance of additive and dominance genetic variation in switchgrass. Ramets were collected from the field and planted into pots to be crossed in the greenhouse and in the field. Crosses are being made with several populations of switchgrass and big bluestem. In Subobjective 2C, more tetraploid and octoploid switchgrass crosses were made in the greenhouse to transfer genes for adaptation and for increasing yield and genetic diversity. Ramets were collected from the field, planted into pots, and crossed in the greenhouse. Field transplanting is planned for next year. In Subobjective 2D, phenotypic data have been collected and most of the previous progeny generations were genotyped by sequencing (GBS). The final cycle of progeny testing was planted in the field and some data analysis initiated. Crosses were made for the mapping population, and one was chosen and transplanted into the field. Genotyping of this mapping population will be completed this summer and data collection this fall. In Subobjective 2E, an additional year of biomass yield was collected and early spring green-up evaluation was completed at two locations in fiscal year (FY)21. Initial greenhouse crosses of promising lines will be completed in FY 22. Objective 3 research continued on Subobjective 3A, switchgrass plants with contrasting responses to rust were grown in a greenhouse and inoculated with rust. Data of responses to rust were recorded and plant tissues collected at regular intervals from infected and non-infected plants. Plant tissues have been stored at -80°C and biochemical analyses are ongoing. For Subobjective 3B, parent plants selected from a field nursery in consultation with geneticist were transplanted into a new field nursery. Originally, ramets from these parent plants were to be moved to a greenhouse for crossing. Due to the delay imposed by max telework, crossing in the greenhouse is projected for FY 23. Analyses of cell walls from material collected in FY 20 is ongoing. Under Subobjective 3C, new genomic data available via DOE is being mined for genes unique to different accessions of switchgrass.
1. Genetic control of climate adaptation and yield increase in switchgrass for bioenergy. In the first evaluation of its kind, ARS researchers in Lincoln, Nebraska, and colleagues identified genetic mechanisms to address both climate adaptation and yield to improve switchgrass for bioenergy. Historically, breeding for improved winter survival and yield required the field evaluation of numerous genotypes across multiple environments to identify plants that exhibited desirable traits. A common problem for breeders has been to identify high-yielding strains with reliable winter survival under variable winter weather conditions. Loci that are associated with both fitness and climate of origin are likely involved in local adaptation and provide strong targets for the breeding of locally adapted cultivars. The genome resources and gene–trait associations developed here provide breeders with the necessary tools to increase switchgrass yield for sustainable bioenergy production. Using these resources in genome-based breeding could reduce the time required to develop newly adapted, high yielding bioenergy cultivars from 10 years to likely as little as 5 years, functionally doubling breeding efforts and accelerating response to a changing climate. This is the first genome-wide evaluation of switchgrass adaptation and yield and is the most important milestone to date for advancing switchgrass breeding for bioenergy.
2. Optimizing genetic data analysis to improve switchgrass for bioenergy. To make improvement, classical plant breeding requires assessing the precision with which estimates of the genetic merits of parents and progeny are measured. As estimates, some level of imprecision is attached to the values used for ranking and selection. Good accuracy indicates that genes responsible for the traits are being targeted and that the parents are passing these genes down to their progeny. Researchers at ARS in Lincoln, Nebraska, evaluated different ways of analyzing genetic data from a switchgrass breeding population under improvement for bioenergy. Combining data from all generations as available and integrating the pedigree in the evaluation provided greater accuracy at selecting for biomass yield, ethanol yield, lignin content, and disease resistance than the traditional one-generation analysis with no pedigree used by switchgrass breeders. This value of accuracy is directly proportional to predicting and making greater progress from breeding and selection. Moreover, a selection index, incorporating all four traits, will be more appropriate to contain the positive relationships between biomass yield, lignin content, and disease resistance and to capitalize on the negative correlation between lignin content and ethanol yield.
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Pingault, L., Palmer, N.A., Koch, K.G., Heng-Moss, T.M., Bradshaw, J.D., Seravalli, J., Twigg, P., Louis, J., Sarath, G. 2020. Differential defense responses of upland and lowland switchgrass cultivars to a cereal aphid pest. International Journal of Molecular Sciences. 21(21). Article 7966. https://doi.org/10.3390/ijms21217966.
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Rukundo, I.R., Danao, M.C., Mitchell, R., Masterson, S.D., Wehling, R.L., Weller, C.L. 2020. Effects of scanning through polypropylene film on predicting nitrogen content in forage using handheld NIR. AIMS Agriculture and Food. 5(4):838-849. https://doi.org/10.3934/agrfood.2020.4.835.
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