Location: Wheat, Sorghum and Forage Research2013 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:
This project has been replaced by project 5440-21000-030-00D “Improving bioenergy and forage plants and production systems for the Central U.S.” on December 14, 2012. In cooperative research with ARS and NRCS soil scientists at Lincoln, NE and Ft. Collins, CO, determined the effects of management practices including N fertilization rates and harvest management for both switchgrass and no-till corn on soil carbon sequestration and biomass yield. The research demonstrated that significant amounts of carbon were being sequestered to depths of 1.5 m in switchgrass and rainfed no-till corn in the western Corn Belt. The long-term switchgrass and corn C sequestration study has been continued. Improved grass experimental strains were developed by breeding for improved forage yield and in vitro dry matter digestibility (IVDMD) and were performance tested in replicated yield and grazing trials. Based on this research, three indiangrass (Sorghastrum nutans) cultivars, ‘Chief’, ‘Scout’, and ‘Warrior’ were released for use in the Great Plains and the Midwest USA in forage-livestock production systems. ‘Chief’ is adapted to USDA Plant Hardiness Zone 4 (HZ 4) and the upper half of HZ 5, ‘Scout’ is adapted to HZ 5, ‘Warrior” is adapted to lower HZ 5 and the upper part of HZ 6 in the Great Plains and Midwest. This research is on-going and will result in additional new cultivars being released in 2013 or 2014. Developed basic molecular biology on the switchgrass genome and gene expression. In cooperation with ARS scientists at Albany, CA and Univ. of Nebraska scientists, deposited over 2,000,000 EST sequences in databases. Over 4 billion expressed RNA reads from switchgrass crowns and rhizomes have been deposited in databases and are being used to study gene expression during fall senescence and spring green-up in switchgrass. Over 30,000 new DNA sequences coding for several genes that likely have an important role in winter-hardiness were obtained. Large datasets of DNA sequences should permit the development of molecular markers for genes controlling winter hardiness in switchgrass which would greatly facilitate the breeding progress for this economically important trait. Basic biochemical factors affecting seed dormancy in switchgrass and other native grasses were determined. This work is being continued to address seed dormancy problems in warm-season grasses. Developed basic management information and technologies for perennial grasses for the Midwest and Great Plains including providing essential field validation research in NE, SD, and ND that resulted in the labeling of the herbicide quinclorac for use on establishing switchgrass. Developed and validated a greenhouse or laboratory stress test for switchgrass that is predictive of field establishment. Developed an efficient method of estimating switchgrass biomass supplies in the field. This and other production research information was made available to producers via an array of extension materials.
1. Switchgrass biomass composition can be significantly modified by breeding for use by biorefineries and cattle. Utilizing plant materials developed by six generations of divergent breeding for In Vitro Dry Matter Digestibility (IVDMD), ARS scientists at Lincoln, NE demonstrated that almost all switchgrass biomass constituents were altered by breeding. It was demonstrated that the divergent breeding altered the plants anatomical structure, conversion to ethanol via saccharification and fermentation in a biorefinery, and fitness as measured by winter survival. High IVDMD plants had low lignin concentration and poor winter survival. It was also demonstrated that lignin was only partly responsible (< 50%) for differences in IVDMD and conversion to ethanol. This research will be used to develop breeding strategies to improve switchgrass and other warm-season grasses for use by ruminants and biorefineries.
2. Switchgrass breeding systems evaluated for use in developing improved switchgrass cultivars. Two breeding systems for improving switchgrass for use as a forage or biomass energy crop were evaluated in a long term study by a Lincoln, NE ARS geneticist for their effectiveness in developing improved cultivars. One breeding method known as the Multi-step Family Selection system theoretically had the potential to result in greater breeding gains per generation but required more work and to date had not been field evaluated. The other method that was tested is known as the Between-and-within family selection system. It requires less field and breeding nursery maintenance work in comparison to the Multi-step Family breeding method. The Between-and-within family selection system produced experimental strains that had the greatest biomass yields and it has the most potential for developing improved switchgrass cultivars for use in pastures and biomass energy production fields. These results will enable switchgrass breeders to improve their effectiveness in developing improved cultivars of switchgrass.
Vogel, K.P., Mitchell, R., Sarath, G., Jung, H.G., Dien, B.S., Casler, M.D. 2013. Switchgrass biomass composition altered by six generations of divergent breeding for digestibility. Crop Science. 53:853-862. DOI 10.2135/cropsci2012.09.0542