Location: Wheat, Sorghum and Forage Research2012 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 1b. Seed has been increased for pending release of one Partridge pea (Chamaecrista fasciculata), two Illinois bundleflower (Desmanthus illinoensis), and two Canada milkvetch (Astragalus canadensis) germplasms that are composite populations developed by intermating plants grown from seed collected from native prairies in specific Plant Adaptation Regions in the Midwest USA. A smooth bromegrass cultivar will be proposed for release based on previously completed small plot trials and the two-year results of a grazing trial (see Objective 2a). Objective 2a. An improved smooth bromegrass strain developed from the cultivar Lincoln by four generations of recurrent breeding for increased forage yield and digestibility was evaluated in a replicated grazing trial with beef yearlings for two years. Cattle grazing the experimental bromegrass strain had 2-year average daily gains of 3.1 lbs per day and a body weight gain of 320 lbs per acre during the spring and early summer grazing season which was 16% greater than that of the widely used cultivar Lincoln. The smooth bromegrass experimental strain has been increased for potential release as a cultivar. Objective 2b. The grassland assessment tool for monitoring switchgrass fields for biomass production has been reported. Due to the limited field-scale use of switchgrass for bioenergy, limited user feedback has been received. A techniques paper for using the grassland assessment tool for grazing and conservation lands is in the final stages of development. Objective 3a. A first study on the transcriptome of switchgrass crowns and rhizomes was completed. These results added about 30,000 new sequences to publically-available switchgrass molecular databases. Several of these transcripts coded for unique proteins which may be involved in determining winter-hardiness. Objective 3b. A lowland type switchgrass with significantly improved winter hardiness and high biomass yields that are equivalent to the biomass yields of released lowland cultivars was developed by crossing lowland and upland tetraploid plants followed by selecting a set of vigorous, non-lodged progeny plants and advancing them through 3 additional generations of population development and breeding. The resulting experimental lowland strain has had excellent winter survival in Nebraska as well as in Wisconsin and Illinois. In eastern Nebraska, its average annual biomass yield for the 2009 through 2011 was 8 tons per acre which was 2.4 tons per acre greater than that of best available released upland cultivar. It is in seed increase for potential release as a cultivar. Objective 4b. The study investigating harvest date and storage affects on dry matter and feedstock composition for switchgrass for bioenergy has been completed. Large round bales had less dry matter loss and fewer changes in feedstock composition during storage than large rectangular bales, especially when harvested after frost. Production fields of both lowland and upland switchgrass strains have been established for additional research in a cooperative USDA-NIFA funded regional project.
1. Improved winter hardiness of switchgrass strains with high biomass yields. Lowland type switchgrass cultivars have greater biomass yield than upland switchgrasses but are largely of southern origin. In the northern half of the US, lowland switchgrass varieties often have winter injury or winter-kill problems. A lowland type switchgrass with improved winter hardiness and high biomass yield was developed by ARS researchers at Lincoln, NE. The lowland-type strain obtained by crossing upland and lowland plants followed by three generations of selection and breeding had excellent winter survival in Nebraska, Wisconsin, and Illinois. In eastern Nebraska average yields were 2.4 tons per acre greater than the best available released upland cultivar. This research demonstrates the feasibility of improving the winter hardiness of switchgrass by breeding. The lowland experimental strain is in the seed increase phase for potential release as a cultivar.
2. Improved knowledge of autumn dormancy and spring-greening of perennial grasses. Molecular mechanisms controlling winter-hardiness and survival could be exploited to accelerate improvements of lowland switchgrass cultivars if they were clearly understood. ARS scientists at Lincoln, NE have developed the first insights into the metabolism of crown and rhizome tissues obtained from a winter hardy upland cultivar of 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.
3. Calibrations for switchgrass biomass composition. Near infrared reflectance spectrometry (NIRS) calibrations for switchgrass biomass composition, developed cooperatively by ARS scientists at Lincoln, NE, Peoria, IL, St. Paul, MN, and Madison, WI, were transferred to the NIRS Forage and Feed Testing Consortium (NIRSC) which is an association of commercial, university ,and government research laboratories, plant research companies, and instrument companies that collaborate to improve NIRS analyses methodology. The NIRSC has transferred these calibration sets and associated standard samples to 19 laboratories. The switchgrass NIRS calibrations enables commercial, industrial, academic, and government laboratories to rapidly determine 20 compositional components of switchgrass biomass. The per sample cost using the ARS developed NIRS calibrations is approximately $5 per sample. Conventional analyses methods would cost over $300 per sample. This technology will significantly facilitate the breeding and management research to develop perennial grasses into bioenergy crops.Schmer, M.R., Vogel, K.P., Mitchell, R., Dien, B.S., Jung, H.G., Casler, M.D. 2012. Temporal and spatial variation in switchgrass biomass composition and theoretical ethanol yield. Agronomy Journal. 104:54-64.