Location: Wheat, Sorghum and Forage Research2010 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 1a: Seed germination tests using two chemicals were validated. Using freshly harvested switchgrass seeds, a number of experiments were conducted that indicated diversity in the dormancy responses in different genotypes. Levels of a plant hormone, abscisic acid, important in the dormancy process were evaluated in switchgrass seeds for the first time by mass spectrometry. These data indicate a correlation between abscisic acid levels and response to external chemicals. Objective 1b. Seed increases of experimental strains of smooth bromegrass, western wheatgrass, tall wheatgrass, and two native legume germplasms have been increased for release pending official approval. Objective 2a: Seed was produced in 2009 and blended with seed lots from previous years to provide adequate seed for pasture planting in autumn 2009. Weed control and adequate precipitation in spring and early summer 2010 promoted successful pasture establishment. Pastures will be fenced and grazed beginning in spring 2011. Objective 2b: Field comparisons of the grassland assessment tool, elongated leaf height and canopy height were completed in bioenergy production systems. Work is still in progress in other grassland systems. Objective 3a. A non-radiometric means to assay a key enzyme in the lignin biosynthesis pathway has been developed. This assay will prove useful to researchers working to understand and improve cell wall properties in feedstocks. Several antibodies were validated by immunoblotting and are ready for use in the protein array. Objective 3b. A lowland type of switchgrass with excellent winter survival and disease tolerance is in accelerated seed increase for potential release. Switchgrass germplasms that are plant hardiness zone composite populations, populations bred for differences in tillering potential, and differing in dry matter digestibility and lignin concentration have been prepared for release in CY10 pending official release approval. Objective 4a. Sub-objective to develop new seed quality tests for big bluestem and indiangrass was deleted in 2010 because of reduced technical support. Objective 4b: Results from a large scale switchgrass bale storage study are being analyzed. Study included big round and big square bales and various storage formats ranging from uncovered outside storage to dry indoor storage. To date, all 2,900 bale samples have been processed and are being analyzed for composition. Objective 4c. A long-term switchgrass soil C sequestration study was established in eastern Nebraska 1998. The study includes two switchgrass cultivars, three N fertilizer rates and two harvest treatments. In the 9 year period from the spring of 1998 to the spring of 2007, soil C increased at rate of 2 Mg per hectare per year in plots in which best management practices were used. These results fully support switchgrass soil carbon sequestration data obtained previously obtained in a five-year study on ten farms in NE, SD, and ND.
1. Switchgrass grown for biomass energy results in significant soil carbon (C) sequestration. A long-term switchgrass soil C sequestration study was established in eastern Nebraska in 1998 by ARS scientists at Lincoln, NE and Ft. Collins, CO. The study includes two switchgrass cultivars, three nitrogen (N) fertilizer rates and two harvest treatments. In the 9-year period from the spring of 1998 to the spring of 2007, soil C increased at rate of 2 metric tons per hectare (0.9 U.S. tons/acre) per year in plots in which best management practices were used. Biomass yields and C sequestration was significantly greater in plots in which N fertilizer was used than in plots where no fertilizer was applied. These results fully support switchgrass soil C sequestration data previously obtained in a five-year study on ten farms in NE, SD, and ND. In the on-farm study which was conducted by ARS scientists at Lincoln, NE and Mandan, ND, additional soil analyses has shown that switchgrass biomass production and harvest resulted in very small changes in available soil phosphorus (P) were very low. Soil P decreased by only 1.5 kg available P per hectare (1.3 lbs P per acre) per year.
2. Herbicides used for establishing switchgrass in the mid-continental USA improve establishment success and accelerate biomass production for bioenergy. Weeds limit switchgrass establishment from seed, but few herbicides are labeled for switchgrass establishment. Selected herbicides were tested on stand establishment and subsequent yields of adapted upland switchgrass cultivars in Nebraska, South Dakota, and North Dakota as well as lowland ecotypes in Nebraska by ARS scientists at Lincoln, NE and Mandan, ND. Applying quinclorac plus atrazine resulted in acceptable stands and high yields at all locations for all ecotypes. Quinclorac, which provides effective control of grassy weeds, and atrazine which provides good broadleaf weed control is an excellent combination for establishing switchgrass in the mid-continental USA. With good management including the use of herbicides, switchgrass can produce yields equivalent to half of full production the establishment year and can be at full production the second year following planting. This research contributed to the labeling of quinclorac for establishing switchgrass for biomass energy in this region and quinclorac is available for use by farmers.
3. Improved real-time assay for plant O-methyltransferases. Plant O-methyltransferases are key enzymes in plant metabolism and play a crucial role in the generation of intermediates during lignin biosynthesis. Earlier assays for these enzymes, and ones specifically involved in lignin biosynthesis were cumbersome and/or involved the use of radioactive substrates. A new method developed by ARS scientists at Lincoln, NE relies on fluorescence as a means to detect and quantify the activity of these enzymes. This new assay can be used in genetic studies to modify lignin composition of biomass which can affect its conversion to liquid fuels.
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