Location: Wheat, Sorghum and Forage Research2009 Annual Report
1a. Objectives (from AD-416)
The long-term objectives of this project are the development of improved perennial grasses and management practices and technologies for use in biomass energy production systems and grazing land in the mid-continental USA. The focus of the research will be on switchgrass for bioenergy and other warm- and cool-season grasses for grazing lands. Over the next five years, the following specific objectives will be addressed: (1) Provide appropriate plant materials for use in pasture-based livestock systems; (2) Improve the economic viability of forage-livestock systems for the Great Plains and North Central States with improved plant materials and management; (3) Provide improved plant materials for harvested biomass used for bioenergy, bioproducts, and forage; and (4) Develop sustainable production systems for harvested biomass and forage.
1b. Approach (from AD-416)
Improved perennial grass cultivars that are adapted to the Central Great Plains and Midwest states that can be used as biomass energy crops or in grazed grasslands will be developed using conventional and molecular breeding technologies. To fully utilize the genetic potential of the improved cultivars, improved management tools and practices will be developed with emphasis on improving establishment success, forage and biomass yield and quality, utilization by livestock, and all aspects of biomass energy crop production. This project is a continuation of a long-term perennial grass breeding and management program that has plant materials and management practices and tools in various stages of development. In this five-year period, focus will be on development of switchgrass cultivars for use in biomass crop production systems, developing cool- and warm-season grass cultivars for use in grazing systems, and native legume germplasm for potential future use in agriculture using conventional and molecular tools. Management research will focus on improved establishment technology for perennial grasses, enhanced methods for evaluating and renovating degraded grasslands, and improved management practices for switchgrass grown as a biomass energy crop including harvest management. Potential economic and environmental benefits of improved plant germplasm and management technologies will be determined in field and pasture trials.
3. Progress Report
Objective 1: Determined effects of different chemicals on switchgrass seed germination. These data indicate that there are exploitable genetic variations for decreasing seed dormancy. Determined that commercial rhizobial inoculum nodulated Partridge pea plants effectively in the greenhouse. Further research on nitrogen-fixation in prairie legumes has been deferred to FY10. Experimental strains of smooth bromegrass, western wheatgrass, and tall wheatgrass are in seed increase for potential release as new cultivars. Composite populations of Illinois bundleflower and Partridge pea have been increased for release as source identified germplasms for expected release in FY10. Objective 2: Seed of an experimental smooth bromegrass strain and an experimental strain of meadow bromegrass is being increased in 0.1 acre seed increase fields to produce seed for potential release as cultivars and for use in replicated grazing trials. Seed yields were unexpectedly low in 2008. Seed harvested from the increase nurseries in 2009 will be used for cultivar release and the establishment of grazing trials. Grassland Assessment Tool data is being prepared for publication. Objective 3: Three switchgrass strains were in seed increase for potential release as cultivars. One lowland strain is being withheld from release because of winter injury during the winter of 2008-2009. One strain has had unexpected seed production problems. One strain will be submitted for release in FY09 or early FY10. Based on yield and composition analyses which enables potential ethanol yield per acre to be determined, it has the higher ethanol yield potential than any cultivar adapted to the Midwest and the Central Great Plains. Breeding work on other switchgrass populations is on schedule. In the molecular biology component of the project, four recombinant proteins were purified and polyclonal antibodies were generated in two different host animals. These antibodies were validated by immunoblotting methods. Several other recombinant proteins are being generated for the manufacture of antibodies. These antibodies will be arrayed on slides (protein microchip) once validated by extensive immunoblotting. Protocols for sample preparation and spotting have been developed, but other studies have been hampered by a lack of easy access to a protein chip arrayer. Objective 4: The second year of a switchgrass bale harvest and storage has been completed in which different baling methods (big round & big square bales) stored inside, outside covered and uncovered, are being evaluated. Bales are being sampled every four months. A long-term study established in 1998 to determine C sequestration of switchgrass managed as a biomass energy crop and no-till maize managed for both grain and grain plus stover production is in progress. Treatments include different N fertility rates, switchgrass harvest dates, and corn stover removal. Data on soil carbon sequestration and biomass and grain harvests for the period 1998-2007 have been summarized and are in preparation for publication. Harvested swtichgrass biomass non-mineral composition has been determined. Mineral composition analysis will be completed in FY10.
1. Development of Near-infrared Reflectance Spectrometry (NIRS) calibrations to predict switchgrass biomass ethanol yield per ton and per acre. Conventional wet chemistry analyses of biomass for composition and conversion to ethanol is time-consuming and expensive. NIRS calibrations have been developed to predict switchgrass cell wall composition, cell wall sugars, soluble sugars, lignin, released and fermented glucose from cell wall cellulose, released cell wall pentoses, and other biomass quality attributes. The calibrations along with biomass yield information enables the following switchgrass bioenergy traits to be rapidly and accurately determined on ground switchgrass biomass: theoretical ethanol yield from hexose sugars, theoretical ethanol yield from pentose sugars, total ethanol yield per Mg (ton) from SSF pre-treated biomass, total ethanol yield per ha (acre), total theoretical ethanol yield per Mg (ton), total theoretical ethanol yield per ha (acre), and conversion ratio of actual to theoretical on a liter to liter basis (gallon/gallon). These calibrations will have multiple uses in breeding, genetics, and management research and could be used by biorefineries to determine ethanol yield of switchgrass biomass. The calibrations were developed by a team of ARS scientists from Lincoln, NE, Peoria, IL, St. Paul, MN, and Madison, WI.
2. Switchgrass strain developed by ARS improves biomass yield and conversion potential. Ethanol yield per acre is dependent upon biomass yield and the conversion potential of the biomass. An experimental strain of switchgrass has been developed by ARS plant scientists that has higher potential ethanol yield per acre than previously available adapted cultivars due to high biomass yields and improved conversion potential. It is the first switchgrass strain with genetically improved potential for conversion to ethanol and demonstrates the feasibility of genetically improving ethanol yield per acre. The experimental strain of switchgrass when grown in eastern Nebraska produced a potential ethanol yield of 355 gallons per acre with existing technology, which is 20 gallons per acre greater than that of the previous best cultivar.
3. Quantifying switchgrass saponins in forage and biomass. Saponins are toxic compounds found in many Panicum species including switchgrass. Switchgrass forage has been used by cattle for decades without deleterious effects but switchgrass forage due to presence of saponins has been reported to cause photosensitization in sheep and horses, a potentially serious condition that can cause the skin to be sunburned and slough off. Saponins can cause liver damage in horses and sheep. To date, it has been easy to determine the presence of saponins, but difficult to quantify how much of the toxic compounds were in switchgrass. A method for quantifying the major saponins in switchgrass has been developed which will enable research to be conducted on the toxicity levels of switchgrass at different maturity stages and under different management conditions. This should enable owners of sheep and horses to avoid potential switchgrass toxicity problems. Cooperative research of ARS scientists at Logan, UT and Lincoln, NE.
4. Efficient methods of estimating switchgrass biomass supplies for biorefineries. Switchgrass (Panicum virgatum L.) is being developed as a biofuel feedstock for the United States. Efficient and accurate methods to estimate switchgrass biomass feedstock supply within a production area will be required by biorefineries. The effectiveness of indirect methods for estimating biomass yields and composition of switchgrass fields were evaluated in a multi-year study. Visual obstruction was the best method for estimating yield on switchgrass fields with low to variable stand densities while elongated leaf height measurements would be recommended on switchgrass fields with high, uniform stand densities. Twenty to 30 elongated leaf height measurements in a field could predict switchgrass biomass yield within 10% with 95% confidence. These procedures can be used by biorefineries in estimation feedstock supply in a production area and also by the USDA National Agricultural Statistics Service (NASS) in estimating national bioenergy supplies from switchgrass.Kiniry, J.R., Schmer, M.R., Vogel, K.P., Mitchell, R. 2008. Switchgrass biomass simulation at diverse sites in the northern Great Plains of the U.S. BioEnergy Research. 1(3-4):259-264.