Frequency Grid: A Simple Tool for Measuring Grassland Establishment

Vogel, Kenneth P.; Masters, Robert A.

doi:10.2307/4003666

Cited by 179 publications

(121 citation statements)

References 7 publications

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“…Prior to harvesting, each plot was rated for stage of reproductive maturity, using a numerical scale that ranged from 3.0 for the boot stage to 4.3 for the soft dough stage [13]. Ground cover was determined immediately after each harvest using two placements of a 25-cell grid [22].…”

Section: Methodsmentioning

confidence: 99%

Changes in Mean and Genetic Variance During Two Cycles of Within-family Selection in Switchgrass

Casler

2010

Bioenerg. Res.

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Switchgrass (Panicum virgatum L.) is a candidate for cellulosic bioenergy feedstock development. Because biomass yield is the most important biological factor limiting the commercial development and deployment of switchgrass as a cellulosic bioenergy feedstock efforts must be undertaken to develop improved cultivars. The objectives of this study were (1) to conduct two cycles of within-family selection for increased biomass yield in WS4U switchgrass and (2) to simultaneously evaluate progress from selection relative to the mean of the original WS4U population. Each of the 150 WS4U families was subjected to phenotypic selection for vigor, seed production, and disease resistance. The mean of all families increased relative to the original WS4U population by 0.36 Mg ha −1 cycle −1 for biomass yield and 3.0% cyclefor ground cover. Gains were uniform across two diverse evaluation locations, indicating that selection gains were robust relative to some variation in Hardiness Zone and soil type. Two cycles of within-family selection led to a homogenization of the diverse families, creating novel recombinations and reducing the family genetic variance to near zero. It is hypothesized that selection and recombination has led to replication of favorable alleles across pedigrees with differing genetic backgrounds, increasing the likelihood of including these favorable alleles in the progeny of future selections. The rate of genetic progress is expected to increase in future cycles of selection with a combination of within-family phenotypic selection and half-sib progeny testing of selected families.

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Section: Methodsmentioning

confidence: 99%

Changes in Mean and Genetic Variance During Two Cycles of Within-family Selection in Switchgrass

Casler

2010

Bioenerg. Res.

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“…Switchgrass stand frequencies were made using a 0.75-m × 0.75-m frequency grid in early June from 2000 through 2005 [30]. Sample areas were randomly chosen by stratification based on cultivar and/or topography within each field.…”

Section: Methodsmentioning

confidence: 99%

Spatial and Temporal Effects on Switchgrass Stands and Yield in the Great Plains

et al. 2009

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Switchgrass (Panicum virgatum L.) is being developed into a perennial, herbaceous, cellulosic feedstock crop for use in temperate regions of the USA. Information on spatial and temporal variation for stands and biomass yield among and within fields in large agroecoregions is not available. Spatial and temporal variation information is needed to model feedstock availability for biorefineries. In this 5-yr study, the spatial and temporal variation for biomass yield and stands was determined among and within 10 fields located in North Dakota, South Dakota, and Nebraska. Switchgrass fields were managed for bioenergy from 2000 to 2004 for the Nebraska locations and 2001 to 2005 for the South Dakota and North Dakota locations. A global positioning system (GPS) receiver was used to repeatedly measure within field quadrat sites for switchgrass stands using frequency grid (2.25 m 2 ) measurements in June for five growing seasons. Sixteen quadrat (≥1 m 2 ) yield samples were taken post-killing frost in the establishment year and in August in subsequent years at each location. Topographic within field effects on switchgrass stand frequency and biomass yields were largely insignificant. Stands tended to increase from establishment year to year 3 and then begin to plateau. Weather factors, which were the principal source of temporal variation, were more important in switchgrass yield variation than on switchgrass stand frequencies. Temporal standard deviations for yield were higher on quadrat sites with higher than average field means while temporal standard deviations were smaller in quadrat sites that had lower than average field means at six locations. In the Northern Great Plains agroecoregion, there is greater temporal and spatial variation for switchgrass biomass yields among fields than within fields. Results indicate that modeling feedstock availability for a biorefinery can be based on field scale yields.

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“…17 A stand frequency of 50% or greater indicates a successful stand, whereas stand frequency from 25 to 50% is marginal to adequate, and stands with less than 25% frequency indicate a partial stand that may need re-seeding. 17 In a study conducted on 10 farms in Nebraska, South Dakota, and North Dakota, switchgrass fi elds with stand frequency of 40% or greater provided a successful establishment year stand threshold for subsequent postplanting year biomass yields. 14 Successful stand establishment during the seeding year is mandatory for economically viable switchgrass bioenergy production systems.…”

Section: Establishing and Managing Switchgrassmentioning

confidence: 99%

Managing and enhancing switchgrass as a bioenergy feedstock

Mitchell

Vogel

Sarath

2008

Biofuels Bioprod Bioref

Self Cite

165

129

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The United States Department of Energy (DOE) has identifi ed switchgrass (Panicum virgatum L.) as a viable perennial herbaceous feedstock for cellulosic ethanol production. Although switchgrass bioenergy research was initiated by USDA-ARS, Lincoln, NE, USA in 1990, switchgrass research has been conducted at this location since the 1930s. Consequently, a signifi cant amount of genetic and agronomic research on switchgrass has been conducted for the Corn Belt and Central Great Plains of the USA that is directly applicable to its use as a biomass energy crop. Similar research must be conducted in other major agroecoregions to verify or modify switchgrass management practices (agronomics) for bioenergy production. The technology to utilize switchgrass for producing ethanol using a cellulosic platform or by pyrolysis to generate syngas is advancing rapidly. Regardless of platform, using switchgrass for ethanol production will require the development of improved bioenergy cultivars or hybrids and improved agronomics to optimize production and will introduce competing uses for the land base. Published in

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Frequency Grid: A Simple Tool for Measuring Grassland Establishment

Cited by 179 publications

References 7 publications

Changes in Mean and Genetic Variance During Two Cycles of Within-family Selection in Switchgrass

Changes in Mean and Genetic Variance During Two Cycles of Within-family Selection in Switchgrass

Spatial and Temporal Effects on Switchgrass Stands and Yield in the Great Plains

Managing and enhancing switchgrass as a bioenergy feedstock

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