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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Research Project #424139

Research Project: Improving bioenergy and forage plants and production systems for the central U.S.

Location: Wheat, Sorghum and Forage Research

2017 Annual Report

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 USA. Over the next five years, the following specific objectives will be addressed. (1) Develop best management practices for Midwest and central Great Plains perennial grass, mixed grass, and grass-legume pastures to increase livestock production, provide biomass feedstocks for bioenergy production, and maintain ecosystem services; (2) Develop new cool- and warm-season grass cultivars and native legume germplasm for Midwest and Great Plains growing conditions; and (3) Identify biomass characteristics that impact conversion efficiency to liquid fuels. Utilize this information to develop improved breeding criteria and improved management practices.

Improved perennial grasses and legumes and associated management practices will be developed for use in the Central Great Plains and Midwest for bioenergy production and grazing when grown on land that is unsuitable or marginal for grain crop production. Perennial plant breeding technologies will be used to develop the improved cultivars. Improved management methods will be developed to fully utilize the genetic potential of the new cultivars by enhancing establishment, yields, and utilization by livestock, and all aspects of biomass energy crop production. Basic molecular biology and biochemistry/physiology information will be developed that will improve the breeding and management products. The project is a continuation of a long-term perennial grass project that has plant materials, management, and basic science studies in various stages of development and completion. Research will be conducted on both C3 (cool-season) and C4 (warm-season) grasses because both are needed in the region to maximize the length of the grazing season. Switchgrass, big bluestem, and indiangrass will be the primary C4 species and will be developed for use in both bioenergy and livestock production systems. Smooth and meadow bromegrass and intermediate, tall, and western wheatgrass will be bred for use in cool-season pastures. Native legumes will be enhanced for use with C4 grasses in biomass production systems. Grass technologies from this research when utilized on 6 million hectares in the Midwest could produce biofuels for 15 million cars. Beef production per hectare from pastures with new cultivars and improved management could be improved by 10 to over 25%.

Progress Report
Objective 1: Warm-season grasses such as switchgrass, big bluestem, and indiangrass are productive for grazing and hay throughout much of the Corn Belt. One strategy for preparing for the emerging bioeconomy is to plant biomass feedstocks, and then graze them while the bioenergy industry develops. Our objective was to compare the best available cultivars of switchgrass, big bluestem, indiangrass, and warm-season mixtures (Mix 1 = big bluestem/indiangrass/sideoats; Mix 2 = big bluestem/indiangrass/switchgrass/sideoats/little bluestem) for livestock production in eastern Nebraska. Fields were planted in 1-acre pastures in spring 2011 with three field replicates per grass species or mixture. Pastures were fertilized each spring after the planting year with 60 lbs of nitrogen per acre. Pastures were grazed in 2012, 2013, 2014, and 2015. In 2012, pastures were grazed with two steers per acre for 69 d. In 2013 and 2014, pastures were grazed with 2 heifers per acre for 74 d and 50 d, respectively. All pastures had greater animal performance in 2012 when steers grazed the pastures. Switchgrass had the lowest average daily gain and gain per acre throughout the study, but the other pastures had similar livestock performance. Averaged across years, mean pasture average daily gains were 1.0 lb/hd/d for switchgrass, 1.5 lb/hd/d for big bluestem, indiangrass, and Mix 1, and 1.6 lb/hd/d for Mix 2. This study demonstrates that warm-season grasses could be planted for biomass feedstocks prior to the presence of a bioenergy market and grazed to return revenue while waiting for the completion of a bioenergy processing facility. Switchgrass is the preferred herbaceous perennial biomass feedstock, but corn stover could provide substantial biomass without significantly altering farm production practices. Year 20 of a long-term switchgrass and no-till corn bioenergy study was initiated on marginally-productive cropland, the longest-term switchgrass and corn comparative study in existence. This study has been a model for collaboration across multiple USDA-ARS research units. Greenhouse gas emissions and analysis of nutrient removal by each cropping system are in the final stages of completion. A replicated field-scale study was established in 2012 near Ithaca, Nebraska to evaluate the production potential of candidate biomass feedstocks on marginally-productive cropland. Our specific objective was to compare the field-scale production of ‘Liberty’ switchgrass, big bluestem, and a low-diversity mixture of big bluestem, indiangrass, and sideoats grama to continuous corn on a poorly drained marginally-productive field. Each crop included 3 field replicates and the perennial grasses received one of two fertilizer treatments (50 or 100 lbs of nitrogen per acre).There was no clear response to fertilizer rate in the perennial grasses, so dry matter yield (DM) was averaged across N rates. Perennial grass DM yields from 2013-2016 represent the total DM that was harvested, baled, and transported from each field to the storage facility and does not include the planting year yield. The 4-year average yields (U.S. tons/acre) were 4.6 tons/acre for big bluestem, 5.0 tons/acre for switchgrass, and 5.6 tons/acre for the low-diversity mixture. The 5-year average corn grain yield for the site was 132 bushels/acre with 1.7 tons/acre of harvested stover. Herbicide damage from glyphosate in 2014 reduced switchgrass yields in 2014 and 2015. Plant samples for compositional analysis have been processed and scanned and predictions are underway. This study demonstrates that perennial grasses grown at the field scale on marginally-productive cropland in eastern Nebraska can reliably produce 5 U.S. tons/acre of dry matter per year to meet potential feedstock demands for the bioeconomy. On average, each acre of perennial grass provided as much biomass as 3-acres of corn stover. Objective 2A: A diversified portfolio of five perennial grass species is being bred for both livestock and bioenergy production systems. Improving these populations to a higher genetic level for yield and quality traits is now based on heritability, genetic correlation, and other genetic parameters. This information is used to update the selection indices for identifying parents with the right combination of genes for increasing yield and for releasing synthetic hybrids as new cultivars. The breeding program has been altered to maintain parents for 1-2 generations, to develop deployment populations, to quantify the genetic merits (breeding values) of both parents and progeny in multi-generational analyses, to integrate the pedigree into the prediction process of those merits, and to assess the value of including disease traits for rusts and mosaic virus in the selection index. Finally, a genomic selection framework using quantitative trait locus mapping, classical genetics, physiology, transcriptomics, and virology is being explored to maximize the genetic potential of switchgrass for biomass and lignin yield and disease resistance. Polycross nurseries of advanced experimental lines of four switchgrass and two wheatgrass breeding populations were established in FY17. First-year seed harvests of switchgrass and wheatgrass crossing nurseries will be completed in FY17. Biomass harvests of three switchgrass and two bromegrass advanced breeding populations were completed in FY17. Objective 2B: Rhizome metabolism during winter dormancy is likely to impact survival, thereby impacting plant stands and sustainability of biomass production. A detailed understanding of seasonal rhizome metabolism will be useful to improve winter hardiness of high yielding germplasm, and to develop cultivars with greater adaptation to the Central Great Plains. Rhizome tissues obtained from field-grown plants of the cultivar summer, which is well adapted to the Central Great Plains, were assessed over two growing seasons using a combination of high-throughput DNA sequencing and analysis of metabolites. These data were used to identify key genes and metabolic pathways that could be of importance during switchgrass rhizome dormancy. Lastly, models of rhizome metabolism, especially during dormancy, were developed that could provide new knowledge of pathways that significantly impact switchgrass rhizome survival over the winter months in the Central Great Plains. These datasets will provide information that can be applied in breeding programs to improve this important perennial crop. In cooperation with ARS and university scientists, a large number of switchgrass cultivars and accessions were evaluated for winter survival at three different locations. All plants are being genotyped. Based on this analysis, it will become possible to separate the genes associated with survivors relative to non-survivors, providing a ready marker-based method to select for elite germplasm that will also have good persistence in the region. Objective 3. Changes to the breeding program have resulted in the identification of new plant selections that are being improved for quality. These plants will be analyzed during the FY17/FY18 growing seasons.

1. Winter annual cover crops provide variable returns when grazed in spring. Winter wheat, cereal rye, and triticale are important cool-season annual forages and cover crops throughout the Great Plains and Midwest. However, there is little information available that compares the profit from grazing these three cover crops. ARS scientists at Lincoln, Nebraska and university colleagues compared steer performance in a 3-yr grazing trial by no-till seeding winter wheat, winter rye, and winter triticale into soybean stubble in the autumn, then grazing the following spring. Each pasture was continuously stocked in spring with four crossbred yearling steers for 17, 32, and 28 d in the three grazing years. Spring forage production was variable, but generally, cereal rye had greater growth than either triticale or wheat. No single forage provided superior steer performance across all years. Based on the 3-year average animal gains per acre and $0.60 per pound of animal gain, however, triticale had a 3-year mean net return of $25.15 per acre per year, followed by wheat at $9.13 per acre per year, while cereal rye lost money at -$11.70 per acre per year. As these small grains provide ecosystem services in addition to forage, grazing cover crops could serve as a mechanism for recovering costs and adds additional value to the crop-livestock system. This effort gives livestock producers information to select the most profitable cover crop for eastern Nebraska.

2. Seed dormancy and germination frequently limit establishment of perennial grasses. Buffalograss seed lots typically have poor germination, largely a result of seed dormancy. Buffalograss seeds, called burs, contain 3 or more potentially germinable caryopses. The mechanisms that control seed dormancy or those that enhance germination in intact buffalograss burs are not known. Germination enhancing treatments developed for switchgrass have shown promise for increasing buffalograss germination. ARS scientists at Lincoln, Nebraska, working with university colleagues, found treating buffalograss seed with potassium nitrate improved water uptake by the burs, which appears to improve germination in buffalograss seed lots.

3. Genetic analysis of a switchgrass population. A switchgrass population derived from crossing two different types chosen to combine the high yield potential and the high winter survival of either parent was used. Breeding has brought some changes in the correlations (relationships) among the three traits. ARS scientists at Lincoln, Nebraska demonstrated selection for high biomass yield in the second generation would meet the goal of simultaneously decreasing lignin content and increasing the ethanol yield of the plants. In the third generation, the same relationships between biomass yield and lignin or between lignin and ethanol yield existed, but the strengths were reduced by about half. The results indicate that greater gains can be achieved with this population, but necessitates monitoring each generation of the relationships among the characteristics in order to ensure their joint improvement.

Review Publications
Donze-Reiner, T., Palmer, N.A., Scully, E.D., Prochaska, T.J., Koch, K.G., Sattler, S.E., Heng-Moss, T., Bradshaw, J., Sarath, G., Amundsen, K., Twigg, P. 2017. Transcriptional analysis of defense mechanisms in upland tetraploid switchgrass to greenbugs. Biomed Central (BMC) Plant Biology. 17(1):46.
Pedersen, M., Wegner, C., Phansak, P., Sarath, G., Gaussoin, R., Schlegel, V. 2017. Detection of mitochondrial respiration changes in wheat seedlings using Fourier transform infrared spectroscopy. Spectrochimica Acta. 173:727-732.
Vogel, K.P., Medill, R., Masterson, S.D., Mitchell, R., Sarath, G. 2017. Mineral element analyses of switchgrass biomass: comparison of the accuracy and precision of laboratories. Agronomy Journal. 109:1-4.
Liebig, M.A., Herrick, J.E., Archer, D.W., Dobrowolski, J., Duiker, S.W., Franzluebbers, A.J., Hendrickson, J.R., Mitchell, R., Mohamed, A., Russell, J., Strickland, T.C. 2017. Aligning land use with land potential: The role of integrated agriculture. Agricultural and Environmental Letters. 2:170007.
Edme, S.J., Mitchell, R., Sarath, G. 2017. Genetic parameters and prediction of breeding values in switchgrass bred for bioenergy. Crop Science. 57:1-11. doi:10.2135/cropsci2016.09.0770.
Schmer, M.R., Brown, R.M., Jin, V.L., Mitchell, R., Redfearn, D.D. 2017. Corn residue utilization by livestock in the USA. Agricultural and Environmental Letters. 2:160043.
Scully, E.D., Donze-Reiner, T., Wang, H., Eickhoff, T., Baxendale, F., Twigg, P., Kovacs, F., Hang-Moss, T., Sattler, S.E., Sarath, G. 2016. Identification of an orthologous clade of peroxidases that respond to feeding by greenbugs (Schizaphis graminum) in c4 grasses. Functional Plant Biology. 43(12):1134-1148. doi:10.1071/FP16104.
Koch, K., Chapman, K., Louis, J., Heng-Moss, T., Sarath, G. 2016. Plant tolerance: A unique approach to control hemipteran pests. Frontiers in Plant Science. 7:1363. doi: 10.3389/fpls.2016.01363.
Frazier, T.P., Xie, F., Palmer, N.A., Tobias, C.M., Donze-Reiner, T., Bombarely, A., Childs, K., Zhang, B., Sarath, G., Zhao, B. 2016. Identification, characterization, and gene expression analysis of nucleotide binding site (NB)-type resistance gene homologues in switchgrass. Biomed Central (BMC) Genomics. 17(1):892. doi:10.1186/s12864-016-3201-5.
Kreuser, K., Kreuser, W., Sarath, G., Amundsen, K. 2016. Potassium nitrate alters buffalograss bur permeability. HortScience. 51(12):1566-1572. doi:10.21273/HORTSCI11126-16.
Moural, T.W., Lewis, K.M., Barnaba, C., Zhu, F., Palmer, N.A., Sarath, G., Scully, E.D., Jones, J.P., Vermerris, W., Sattler, S.E., Kang, C. 2016. Chracterization of class III peroxidases from switchgrass. Plant Pathology. 173(1):417-433. doi:10.1104/pp.16.01426.