Location: Wheat, Sorghum and Forage Research
2023 Annual Report
Objectives
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)
Approach
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.
Applying N fertilizer in the planting year for perennial grasses like switchgrass, big bluestem, and Indiangrass is not well studied and is poorly understood. We will evaluate the interaction of seeding rate, N rate, and N formulation on switchgrass establishment and planting year yield. Although N fertilization on established switchgrass has been studied broadly, little research has been conducted to determine the role of N formulation and application timing. For studies on established stands, we will evaluate the effects of N rate and N formulation (granular vs. foliar-applied) applied at three different growth stages on subsequent switchgrass yield and composition. These studies will serve as baselines and will be expanded to different species and cultivars.
Progress Report
The project has three main components, management, breeding, and molecular biology/biochemistry. This project leads the development of switchgrass into a biomass energy crop, has developed much of the management information for switchgrass grown as a biomass energy crop, has developed most of the grasses and associated management information used for grassland reseeding in the central U.S., and has numerous collaborations. 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 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. Precipitation was a limiting factor in 2021, 2022, and is impacting 2023. This was particularly evident in our wheat, rye, and triticale pastures that were late in becoming ready to graze and had limited early spring growth. 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 transition of the Shawnee switchgrass pasture to a warm-season grass mixture pasture (seeded in spring 2021) is complete and the mixture is well established. The Liberty switchgrass is recovering from the dry conditions, and pasture improvements applied in 2021 have improved the stand. The pastures were not grazed in 2023 and will be harvested for hay. The Newell smooth bromegrass pasture was harvested for hay and yielded 0.94 tons/acre, an indication of the carryover response of the dry growing conditions. The dryland corn will be managed as planned. Grazing wheat, rye, and triticale in the spring before planting soybeans has produced a 3-year mean average daily gain (pounds/head/day) of 2.9 for wheat, 3.4 for rye, and 2.8 for triticale. In Subobjective 1B, field practices continued and 2023 represents the 26th year of growing switchgrass and no-till corn on marginally productive cropland. This long-term field study is the first to demonstrate that continuous corn and perennial grass systems maintain or mitigate atmospheric greenhouse gases during the agronomic phase of bioenergy production and that soil organic carbon continues to increase on marginally productive croplands. In Sub-objective 1C, the field-scale production of Liberty switchgrass, big bluestem, a low-diversity warm-season grass mixture, and Independence switchgrass continued. Dry growing conditions in late 2021 and early 2022 limited growth in these fields and effects of the dry conditions are carrying over into 2023. Independence switchgrass stands have been damaged by drought and winterkill and will have reduced yield in 2023. Fields will be harvested after a killing frost.
Objective 2 research continued developing new forage and biomass germplasm and cultivars for the central U.S. A multivariate selection approach that analyzes all traits and generations together has been initiated. While extensive field phenotyping was realized, obtaining lab data is the bottleneck of this project. In Sub-objective 2A, five perennial grass species are being bred for both livestock and bioenergy production systems. A genomic selection framework using quantitative trait locus mapping, is being evaluated to maximize the genetic potential of switchgrass for biomass yield, quality, and rust and mosaic disease resistance. Most of the planned research and outputs are met. In Sub-objective 2B, the crosses have been expanded with several populations of switchgrass. Crosses were made within and across populations as biparental and polycrosses. Field phenotyping will begin in fall 2023. In Sub-objective 2C, as a first in switchgrass, crosses were made between tetraploid and octoploid switchgrass using a 4x-derived octoploid germplasm as a bridge to transfer genes for adaptation and for increasing yield and genetic diversity. Field phenotyping will start in fall 2023. Data from multi-location trials were collected and partially shared with this project for potential release of a switchgrass variety. In Subobjective 2D, a genetic analysis of rust data collected from field and lab experiments was published and the genomic selection will follow immediately after upgrading our hardware to handle this large volume of data.
Objective 3 research was substantially completed, in readiness for the start of new project plans in FY 2024. Specifically, all milestones for Sub-objective 3A were completed. For Subobjective 3B, parent plants selected from a field nursery in consultation with an ARS-Lincoln geneticist were transplanted into a new field nursery in FY 2022. Originally, ramets from these parent plants were to be moved to a greenhouse for crossing. Plants will be sampled in Fall FY 2023. Under Subobjective 3C, rhizome metabolism over the course of a growing season was compared between a lowland and upland switchgrass cultivars. Genomic sequencing of several switchgrass plants (including parent, and half-sib families) have been completed and data are being processed.
Accomplishments
1. Metabolic difference in rhizomes differentiate adapted and non-adapted switchgrass cultivars. Switchgrass can grow new shoots every year from below ground rhizomes. Death of rhizomes due to winter kill can strongly impact future yields and sustainability of biomass production. ARS scientist in Lincoln, Nebraska, investigated rhizome metabolism in two cultivars, Kanlow (southerly adapted), and Summer (northerly adapted) to detect differences in rhizome metabolism that influence winter dormancy. In both cultivars, the plant hormone abscisic acid levels increased and were a common determinant driving switchgrass dormancy. However, delayed transition to rhizome dormancy in the southerly adapted Kanlow is likely a factor that increases winter kill in this cultivar relative to the northerly adapted Summer. Genes and regulatory mechanisms that influence the timing for dormancy onset will be important to the deployment of high yielding hybrid cultivars in more northerly sites in the U.S.
2. Estimating genetic variation and gains for rust resistance in an inter-ecotypic population of switchgrass bred for bioenergy. Two generations of switchgrass were studied by ARS scientists in Lincoln, Nebraska, to discriminate families and progeny for resistance or susceptibility to fungal infections. Significant genetic variation was detected in the switchgrass genetic population and satisfactory progress can be made by breeding and selection. This study suggested that reducing the incidence of rust in switchgrass is readily attainable through breeding for ultimate deployment of cultivars with durable resistance that potentially benefit farmers, the livestock and bioenergy industries.
3. Perennial grass energy crop effects on soil carbon and nitrogen. Incorporating native perennial grasses on marginal cropland can increase agroecosystem resilience by diversifying rural energy production and improving soil health. ARS researchers in Lincoln, Nebraska, conducted a five-year study that evaluated soil organic carbon, total soil nitrogen, and biomass for native perennial warm-season grasses with different nitrogen fertilizer rates compared to no-till continuous corn. Neither soil organic carbon nor total soil nitrogen changed over time under either the warm-season grasses or corn. Both soil organic carbon and total soil nitrogen were generally greater in the low-diversity mixture compared to the big bluestem. The effect of nitrogen fertilizer on warm-season grass biomass was inconsistent. Biomass was generally greater in the low-diversity mixture after the first harvest year. Growing native perennial grasses on marginal cropland can maintain soil organic carbon and soil nitrogen stocks while providing a significant source of biomass to be used in energy production or in integrated livestock systems, benefiting farmers, the bioenergy industry, and the nation’s natural resources.
Review Publications
Cardona, J.B., Grover, S., Bowman, M.J., Busta, L., Sarath, G., Sattler, S.E., Louis, J. 2023. Sugars and cuticular waxes impact sugarcane aphid (Melanaphis Sacchari) colonization on two different developmental stages of sorghum. Plant Science. 330. Article 111646. https://doi.org/10.1016/j.plantsci.2023.111646.
Zhang, B., Lewis, J., Kovacs, F., Sattler, S.E., Sarath, G., Kang, C. 2023. Activity of cytosolic ascorbate peroxidase (APX) from panicum virgatum against ascorbate and phenylpropanoids. International Journal of Molecular Sciences. 24. Article 1778. https://doi.org/10.3390/ijms24021778.
Palmer, N.A., Sarath, G., Bowman, M.J., Saathoff, A.J., Edme, S.J., Mitchell, R., Tobias, C.M., Madhavan, S., Scully, E.D., Sattler, S.E. 2023. Divergent metabolic changes in rhizomes of lowland and upland switchgrass (panicum virgatum) from early season through dormancy onset. Plants. 12(8). Article 1732. https://doi.org/10.3390/plants12081732.
Ramirez II, S., Schmer, M.R., Jin, V.L., Mitchell, R., Eskridge, K. 2023. Near-term effects of perennial grasses on soil carbon and nitrogen in eastern Nebraska. Environments. 10(5). Article 80. https://doi.org/10.3390/environments10050080.
Potash, E., Guan, K., Margenot, A., Lee, D., Boe, A., Douglass, M., Heaton, E., Jang, C., Jin, V.L., Li, N., Mitchell, R., Namoi, N., Schmer, M.R., Wang, S., Zumpf, C. 2023. Multi-site evaluation of stratified and balanced sampling of soil organic carbon stocks in agricultural fields. Geoderma. 438. Article 116587. https://doi.org/10.1016/j.geoderma.2023.116587.
