120 research outputs found

    Ecovar Development on the Northern Great Plains of North America

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    The objective of this study was to develop sources of seed of native plant species to facilitate commercial seed production of ecovars suitable for revegetation and reclamation of disturbed land. An ecovar or ecological variety is native plant material derived from a composite of germplasm collected throughout the area of adaptation and that contains the natural genetic diversity of the species. Ecovars are currently being developed or proposed for 24 species of grass, legume and shrub species from the northern great plains. The research is conducted by scientists at nine research centres from six agencies in two countries. Seed from the first ecovar, developed from 250 accessions of Needle-and-Thread grass received pedigree status in 1996. Associated research studies will determine the degree of genetic variability existing among the accessions and any shifts in genetic diversity resulting from selection

    Genetic variation and correlation of agronomic traits in meadow bromegrass (Bromus riparius Rehm) clones.

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    Meadow bromegrass (Bromus riparius Rehm.) is a recently introduced pasture grass in western Canada. Its leafy production and rapid regrowth have made it a major grass species for pasturing beef animals in this region. As relatively little breeding work kas been done on this species, there is little information on its breeding behaviour. The main objective of this study was to estimate total genetic variability, broad-sense heritability, phenotypic and genetic correlations. Forty-four meadow bromegrass clones were evaluated for agronomic characters. Genetic variation for dry matter yield, seed yield, fertility index, harvest index, plant height, plant spread, crude protein, neutral de ter gent fiber and acid de ter gent fiber, was significant. Broad-sense heritability estimates exceeded 50% for all characters. Heritability estimates were at least 3.5 times greater than their standard errors. Phenotypic and genetic correlation between all possible characters were measured There was general agreement in both sign and magnitude between genetic and phenotypic correlations. Correlations between the different characters demonstrated that it is possible to simultaneously improve seed and forage yield. Based on the results, it appears that the development of higher yielding cultivars with higher crude protein, and lower acid and neutral detergent fibers concentration should be possible

    Hybrids Between Meadow and Smooth Bromegrass: A New Forage Crop for Canada

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    Smooth bromegrass (Bromus inermis Leyss.) has been an important hay grass in the agricultural regions of western Canada for approximately 50 years. Meadow bromegrass (B. riparius Rehm.) has become the most important pasture species in this region over the last 15 years. It is possible to produce hybrids between these species, which could lead to the development of a type of bromegrass which would be useful for both hay and pasture purposes

    Tumbleweeds and airborne gravitational noise sources for LIGO

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    Gravitational-wave detectors are sensitive not only to astrophysical gravitational waves, but also to the fluctuating Newtonian gravitational forces of moving masses in the ground and air around the detector. This paper studies the gravitational effects of density perturbations in the atmosphere, and from massive airborne objects near the detector. These effects were previously considered by Saulson; in this paper I revisit these phenomena, considering transient atmospheric shocks, and the effects of sound waves or objects colliding with the ground or buildings around the test masses. I also consider temperature perturbations advected past the detector as a source of gravitational noise. I find that the gravitational noise background is below the expected noise floor even of advanced interferometric detectors, although only by an order of magnitude for temperature perturbations carried along turbulent streamlines. I also find that transient shockwaves in the atmosphere could potentially produce large spurious signals, with signal-to-noise ratios in the hundreds in an advanced interferometric detector. These signals could be vetoed by means of acoustic sensors outside of the buildings. Massive wind-borne objects such as tumbleweeds could also produce gravitational signals with signal-to-noise ratios in the hundreds if they collide with the interferometer buildings, so it may be necessary to build fences preventing such objects from approaching within about 30m of the test masses.Comment: 15 pages, 10 PostScript figures, uses REVTeX4.cls and epsfig.st

    Promising native forage options for semi-arid prairies of western Canada

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    Non-Peer ReviewedThere is growing interest in native plant species for their use as forage, pasture, energy crop, and as land reclamation and revegetation materials. This article reports the results of population improvement work on northern wheatgrass (NWG), purple prairie clover (PPC), white prairie clover (WPC) and plains rough fescue (PRF) carried out at Swift Current Research and Development Centre - Agriculture and Agri-Food Canada. Substantial selection differential were achieved in all species in terms of growth vigour, plant health, biomass and seed yield in all species. This suggests ample scope for selection gain for the desirable traits. Seed shattering is one of the challenges facing the domestication and commercialization of these native plant species
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